The risk of TESE-induced hypogonadism: a systematic review and meta-analysis

The risk of TESE-induced hypogonadism: a systematic review and meta-analysis Abstract BACKGROUND Testicular sperm extraction (TESE) is a surgical procedure to retrieve spermatozoa from the testes of men with azoospermia to help them achieve biological parenthood. Although effective, the surgical procedure is not without complications and haematoma, devascularization, inflammation and a decrease in testosterone levels have been described as such. The prevalence and duration of hypogonadism and associated symptoms after TESE have not been studied systematically. OBJECTIVE AND RATIONALE In this systematic review we addressed the following research questions: Are serum testosterone levels decreased after TESE and, if so, do these levels recover over time? What is the prevalence of symptoms and signs related to hypogonadism after TESE and are they related to testosterone levels? SEARCH METHODS We searched the databases Pubmed and Embase from 1 January 1993 to 26 June 2017. We combined subject headings with terms in title and/or abstract for participants, intervention and outcomes. We included all studies that reported on TESE, regardless of the specific technique used, that measured testosterone and/or LH, and/or had information on signs or symptoms related to hypogonadism as defined by hypogonadism guidelines. An additional inclusion criterion was that studies described these measurements both before and after TESE. The quality of the included studies was assessed using the Risk Of Bias In Non-randomized Studies—of Interventions tool. OUTCOMES We identified 15 studies reporting on total testosterone levels of which five studies also reported on testicular volume and one study on erectile dysfunction. Men with Klinefelter syndrome and men with non-obstructive azoospermia had the strongest decrease in total testosterone levels 6 months after TESE, with a mean decrease of 4.1 and 2.7 nmol/l, respectively, which recovered again to baseline levels 26 and 18 months after TESE, respectively. At 6 months after TESE, some studies reported serum total testosterone concentrations below a cut-off value of 12 nmol/l, where symptoms and signs related to hypogonadism may appear. Furthermore, an increased prevalence of erectile dysfunction related to decreased total testosterone levels 6 months after TESE was reported. Also, in some men a decrease in testicular volume was reported. However, it is not clear if this is related to low testosterone levels. WIDER IMPLICATIONS The transient, but statistically significant, decrease in total testosterone levels indicates that men are at risk of developing a temporary hypogonadism after TESE, but there is insufficient evidence for whether patients actually experience clinical symptoms in case of decreased serum testosterone levels. To be able to properly counsel TESE patients, more large-scale monitoring on signs and symptoms of hypogonadism, in combination with testosterone measurements, needs to be performed in men undergoing TESE. testosterone, azoospermia, assisted reproduction, testicular sperm extraction, hypogonadism, erectile dysfunction, non-obstructive azoospermia, Klinefelter syndrome, sperm retrieval Introduction Testicular sperm extraction (TESE) is a surgical procedure to assist men with azoospermia to achieve biological parenthood. With this technique spermatozoa can be retrieved directly from the testicular tissue and subsequently used for ICSI. In 1993, the first successful fertilization, and soon after that the first pregnancy, with testicular sperm after ICSI were described (Craft et al., 1993; Schoysman et al., 1993). Since then, the technique developed further and at present various TESE techniques have been reported, such as multibiopsy/conventional TESE, microdissection TESE and testicular sperm aspiration (TESA) (Craft et al., 1993; Bourne et al., 1995; Schlegel and Li, 1998). Evidence that one technique should be preferred over the other based on sperm retrieval rates, pregnancy rates, live birth rates and complications are limited (Donoso et al., 2007; Van Peperstraten et al., 2008). Although a higher sperm retrieval rate is described for men with non-obstructive azoospermia (NOA) after microdissection TESE compared to conventional TESE, this is not true for all men and depends on the type and cause of azoospermia (Deruyver et al., 2014). Currently, TESE is the only possible therapy for men with NOA to obtain spermatozoa to father their own genetic children. In case of obstructive azoospermia (OA), microsurgical epididymal sperm aspiration or percutaneous epididymal sperm aspiration is the preferred method to retrieve spermatozoa (Van Wely et al., 2015). If unsuccessful, a subsequent TESE procedure could also be offered to these men. TESE is now routinely offered worldwide to men with azoospermia with a success rate of retrieval of spermatozoa of ~50% for men with NOA and Klinefelter syndrome, and can go up to 100% for men with OA (Chan and Schlegel, 2000; Cissen et al., 2016; Corona et al., 2017). The described live birth rates for ICSI with testicular retrieved spermatozoa vary from 10 to 45% per cycle for all types of azoospermia (Bocca et al., 2017; Corona et al., 2017; Esteves and Agarwal, 2013; Meijerink et al., 2016). In the TESE procedure a small biopsy of testicular tissue is obtained via dissection followed by tissue resection, while with TESA small pieces of tissue are aspirated to extract spermatozoa. Post-operative complications, such as haematoma, devascularisation and inflammation, have been described, eventually leading to scars and calcification (Schlegel and Su, 1997; Donoso et al., 2007). Furthermore, a decrease in serum testosterone levels after a TESE procedure has been described (Donoso et al., 2007; Shin and Turek, 2013). Decreased testosterone levels can subsequently lead to hypogonadism. Symptoms of hypogonadism have been described to occur more often when total testosterone levels are below a threshold of 12 nmol/l, and the lower the total testosterone values, the more frequent the symptoms of hypogonadism will be present (Bhasin et al., 2011; Dohle et al., 2015; Zitzmann et al., 2006). According to various guidelines on hypogonadism, the diagnosis is based on the presence of one or more signs or symptoms. Symptoms can be—among others—erectile dysfunction (ED), decreased muscle strength and loss of libido. Additional signs, for example, decrease in bone mineral density and a decrease in testicular volume can occur (Table I) (Wang et al., 2009; Bhasin et al., 2010; Jungwirth et al., 2015). Because many of these clinical manifestations are not specific for hypogonadism, the diagnosis should always be confirmed by measuring serum testosterone levels (Bhasin et al., 2010; Dohle et al., 2015). Table I Signs and symptoms associated with androgen deficiency in men. Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia Table I Signs and symptoms associated with androgen deficiency in men. Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia The prevalence and duration of hypogonadism and associated symptoms as a result of the TESE procedure have not been studied systematically. This information is necessary to properly counsel men who qualify for TESE on the potential risk of developing hypogonadism after TESE. We therefore systematically reviewed the literature and included all studies that measured testosterone levels, LH levels and/or signs and symptoms related to hypogonadism before and after TESE. In this systematic review we addressed the following research questions: Are serum total testosterone levels decreased after TESE and, if so, do these levels recover over time? What is the prevalence of symptoms and signs related to hypogonadism after TESE and are they related to total testosterone levels? Methods This review is reported according to the PRISMA statement (The Prisma Group from Moher D, Liberati A, Tetzlaff J, 2009). Prior to the search, a plan regarding the study design, search methods and inclusion and exclusion criteria was written and approved by all authors. We registered the protocol at Prospero with registration number CRD42016052596 and is available from http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42016052596. Search and study selection We searched the databases Pubmed and Embase from 1 January 1993, when the first TESE procedure was described, to 26 June 2017. We combined subject headings with terms in title and/or abstract for the intervention, outcomes and participants. The details of the search are displayed in Supplementary Tables SI and SII. Two authors (J.E. and A.v.P.) screened the articles independently on title and abstract for eligibility based on predefined inclusion criteria. Then both authors carefully read the full text independently to further exclude studies which did not meet the inclusion criteria. When there was discrepancy between the authors, articles were discussed until agreement was achieved. Eligibility criteria We included all original English, peer-reviewed articles, irrespective of study-design. There were no restrictions in TESE techniques. We included all studies which measured testosterone, LH, or signs or symptoms related to hypogonadism (Table I), defined according to international hypogonadism guidelines (Bhasin et al., 2010; Dohle et al., 2015; Wang et al., 2009). To assess the association between TESE and hypogonadism and its associated signs and symptoms, we only included the studies that performed the measurements before and after TESE. Furthermore, we excluded studies that included prepubertal boys because of the difference in baseline characteristics and testosterone and LH levels compared to adult men. Data extraction One author (J.E.) extracted data from the included articles. The following data were extracted when available: first author, year of publication, study design, TESE technique, number of participants, age of participants, type of azoospermia, type of outcome and outcome in mean values with SD or prevalence of the outcome. When data of the outcomes were not available we contacted the corresponding authors to ask for the data. If we did not receive the raw data, but they were displayed in graphs, we extracted the data from the graphs. Quality assessment Two authors (J.E. and M.v.W.) assessed the quality of the included studies using the Risk Of Bias In Non-randomized Studies—of Interventions tool (Sterne et al., 2016). With this tool we estimated the risk of bias due to confounding, selection of participants into the study, classification of intervention, deviations from intended interventions, missing data, measurements of outcomes and selection of the reported results. Data analyses To study the effect of TESE on testosterone levels over time we used the mean testosterone levels from individual studies to perform meta-regression analyses using STATA 14.2 software (StataCorp, College Station, TX, USA). Where possible we identified different patient groups based on their type of azoospermia, namely, men with OA, men with NOA and men with Klinefelter syndrome. To calculate the individual odds ratios (OR) and individual and pooled mean differences with corresponding 95% CI we used Review Manager 5.3 (The Cochrane Collaboration, The Nordic Cochrane Centre, Copenhagen, Denmark). Binary outcomes were expressed as OR and continuous outcomes as mean differences. To calculate mean differences we compared the outcomes after TESE with outcomes before TESE. A random effect model was standardly applied. Data were pooled based on the patient groups described above and on follow-up time. We classified follow-up time of 1–3 months as short term, 6 months as intermediate, 9–12 months as intermediate-long, and when the follow-up was more than 12 months this was classified as long term. Results Study selection With our systematic search we identified 611 reports from PubMed and 1011 from Embase. After removing duplicates, 1255 reports remained for screening of eligibility in title and abstract. Based on our inclusion criteria, we included 47 reports for reading the full text, of which we excluded 32 studies that did not meet the inclusion criteria. Eventually, we included 15 studies for our systematic review. The corresponding flowchart is depicted in Fig. 1. Figure 1 View largeDownload slide Flowchart of the search and selection of literature on induced hypogonadism after testicular sperm extraction in men. TESE, testicular sperm extraction. Figure 1 View largeDownload slide Flowchart of the search and selection of literature on induced hypogonadism after testicular sperm extraction in men. TESE, testicular sperm extraction. Study characteristics All 15 included studies reported on serum levels of total testosterone before and after TESE. Nine studies also reported serum LH levels and six studies reported on symptoms or signs of hypogonadism in addition to the hormone levels (Table II). The 15 studies were published between 1998 and 2017. The study with the smallest number of patients included 15 men and the study with the largest number of patients included 435 men, although they only reported testosterone levels before and after TESE from 142 men. The age of the men varied between 25 and 61 years. In all studies men with NOA were included; five studies also included men with OA and eight studies also included men with Klinefelter syndrome. In some of these studies the data for the various types of azoospermia were not separated. The TESE techniques used varied between studies (TESA, multiple biopsy/conventional, microdissection TESE and Trucut needle). The follow up of the men varied between 1 month and 46 months after TESE. Table II Basic characteristics of studies on testicular sperm extraction included in this review. Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH *Data not described separately for the different patient groups. TESE, testicular sperm extraction; NOA, non-obstructive azoospermia; OA, obstructive azoospermia; KF, Klinefelter syndrome. Table II Basic characteristics of studies on testicular sperm extraction included in this review. Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH *Data not described separately for the different patient groups. TESE, testicular sperm extraction; NOA, non-obstructive azoospermia; OA, obstructive azoospermia; KF, Klinefelter syndrome. Quality assessment We assessed the risk of bias on confounding as low in all studies since we only included studies comparing data after TESE with that before TESE. We assessed the risk of bias on selection of participants as unclear in studies that did not describe men with OA as a separate group from men with NOA (n = 3), and high in the studies that included men with Klinefelter syndrome together with men with NOA (n = 5). In studies in which men who had undergone TESE for the second or third time were included, we determined the risk of bias on selection of participants as unclear (n = 3). We determined the risk of bias in classification of intervention as unclear in studies in which different TESE techniques were applied but assessed the outcome as one group (n = 2) and in studies in which one testis was biopsied in some men but both testes in others (n = 1). Some studies did not describe all men in the follow up, which we assessed as an unclear (n = 8) or high (n = 4) risk of bias on missing data. We assigned an unclear bias in measurements of outcome to studies that did not report at what time during the day blood samples were taken for hormone levels (n = 4), or studies that did not report cut-off values on low total testosterone (n = 1). In studies that reported a different follow-up time per man we also assessed the risk of bias in measurements of outcome as unclear (n = 3). We assessed the risk of bias selection of reported results as unclear in 13 out of 15 studies (87%). The detailed information on the quality assessed per study can be found in Fig. 2. Figure 2 View largeDownload slide Risk of bias summary for the 15 studies selected from the literature review. Figure 2 View largeDownload slide Risk of bias summary for the 15 studies selected from the literature review. Testosterone levels after TESE From the 15 studies that measured serum total testosterone levels before and after TESE, one study only reported the testosterone levels of the men with new-onset of ED after TESE. In these men, serum total testosterone levels were significantly decreased after TESE (Akbal et al., 2010). Another study reported a decrease of serum testosterone levels 3–6 months after TESE, and a recovery of these levels after 18 months in both microdissection and conventional TESE, but did not report SDs (Ramasamy et al., 2005). We did not include these two studies in our meta-analyses. Mean testosterone levels after TESE Twelve studies compared mean total testosterone levels before and after TESE (Table III). Meta-regression analysis showed a significant decrease in total testosterone levels at 3, 6, 9 and 12 months after TESE compared to before, which recovered to normal values again at 18 months (Fig. 3A). There was a lot of variation in testosterone levels between studies before TESE. To reduce this heterogeneity we analysed two patient groups separately, i.e. men with Klinefelter syndrome (three studies) and men with NOA (five studies). It was not possible to identify separate data for men with OA. Table III Characteristics of studies that measured testosterone levels after TESE. First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels *Not included in meta-regression analysis. Table III Characteristics of studies that measured testosterone levels after TESE. First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels *Not included in meta-regression analysis. Figure 3 View largeDownload slide Overview of mean serum total testosterone levels in men after TESE over time. Total testosterone levels are shown in (A) all men, (B) men with Klinefelter syndrome and (C) men with non-obstructive azoospermia. Figure 3 View largeDownload slide Overview of mean serum total testosterone levels in men after TESE over time. Total testosterone levels are shown in (A) all men, (B) men with Klinefelter syndrome and (C) men with non-obstructive azoospermia. For men with Klinefelter syndrome, in total data for 54 men were available (Takada et al., 2008; Ishikawa et al., 2009; Bobjer et al., 2012). There was a significant decrease in total testosterone levels after TESE, but these levels recovered to baseline values after 26 months (Fig. 3B). In one out of three studies, the mean testosterone levels in men with Klinefelter syndrome were above the threshold for hypogonadism of 12 nmol/l at baseline (Bobjer et al., 2012). The meta-analysis using mean differences shows the strongest mean decrease in total testosterone at 6 months after TESE with a mean decrease of 4.13 nmol/l (95% CI: −5.86, −2.40) (Supplementary Fig. S1A). The mean total testosterone levels rose at long-term follow-up (>12 months) to a mean difference of −2.28 nmol/l (95% CI: −4.03, −0.53), but the total testosterone levels remained significantly lower compared to the levels before TESE. For men with NOA we were able to include five studies with a total of 252 men (Manning et al., 1998; Takada et al., 2008; Ishikawa et al., 2009; Ozturk et al., 2011; Bobjer et al., 2012). In these men we found variations in baseline mean total testosterone levels with some mean total testosterone levels below the threshold for hypogonadism of 12 nmol/l (Fig. 3C). We found the largest decrease in mean total testosterone levels 6 months after TESE, of 2.72 nmol/l (95% CI: −5.02, −0.41) (Supplementary Fig. S1B). Our meta-analysis shows a significant decrease in mean total testosterone levels at 9–12 months after TESE, which disappears at long-term follow-up. In most studies LH levels were associated with testosterone levels; when a decrease in total testosterone was reported, a significant increase in LH was found (Takada et al., 2008; Altinkilic et al., 2017; Binsaleh et al., 2017) and when no decrease in total testosterone was reported, also no increase in LH was found (Steele et al., 2001; Everaert et al., 2006; Bobjer et al., 2012). In one study no decrease in serum testosterone after TESE in men with NOA and OA was reported, but an increase in LH levels after TESE was seen (Ishikawa et al., 2009). In the same study (Ishikawa et al., 2009) in men with Klinefelter syndrome a decrease in testosterone after TESE was reported, but no increase in LH levels. One study examined Leydig cell function by performing an hCG test within a period of 4–32 months after TESE (Schill et al., 2003). Out of 13 men with NOA with low serum testosterone levels measured before or after TESE, three men had insufficient increase in testosterone levels after stimulation with hCG (<1.5-fold increase). In addition, 6 out of 15 men with NOA with normal testosterone levels before and after TESE showed insufficient testosterone increase after hCG stimulation, indicating a disturbed functioning of Leydig cells. Prevalence of low testosterone after TESE Five studies described the prevalence of low total testosterone levels after TESE, using thresholds varying from 5 to 12 nmol/l, or this was not specified. In total, 229 men were involved (Table III). The ORs per study show that there is a trend towards an increased risk for low total testosterone levels after TESE (Fig. 4). Because of the differences in follow-up time and in thresholds used for low testosterone levels, pooling of the data was not informative. Figure 4 View largeDownload slide Forest plot with odds ratio of low total testosterone in men after TESE. Figure 4 View largeDownload slide Forest plot with odds ratio of low total testosterone in men after TESE. Risk of symptoms and signs related to hypogonadism after TESE Our systematic literature search revealed that only six studies reported on symptoms or signs associated with hypogonadism after TESE (Table IV). The reported symptoms and signs are limited to ED (Akbal et al., 2010) and changes in testicular size (Altinkilic et al., 2017; Esteves, 2002; Okada et al., 2002; Ozturk et al., 2011; Schill et al., 2003). Table IV Basic characteristics of studies that measured symptoms or signs related to hypogonadism after TESE. First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml Table IV Basic characteristics of studies that measured symptoms or signs related to hypogonadism after TESE. First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml Risk of ED after TESE The risk of ED after TESE, one of the symptoms of hypogonadism, was described in one study in which 13 out of 66 men with new-onset ED were reported 6 months after TESE (Akbal et al., 2010): men with NOA and undergoing microdissection TESE were included. Overall, 13 men had a score of ≥22 according to the International Index of Erectile Function-5 (IIEF-5) questionnaire, indicating no ED, before TESE and ≤21, indicating ED, after TESE. However, a score of ≤21 was reported in 28 men before TESE and 35 men after TESE, respectively. Although ED was subdivided into mild, moderate and severe depending on the score, no details were reported on the severity of ED in each patient. Out of the 13 men with new-onset ED, one man had successful retrieval of sperm, while from the other 12 men no sperm was retrieved. Hormonal levels were measured in 36 men, but only the data of the 13 men with new-onset ED are reported. In these men the mean total testosterone level was significantly decreased from 27.1 to 9.7 nmol/l. LH was increased in these men, but not significantly. All 13 men reported depression and anxiety after TESE, assessed with the Hospital Anxiety and Depression Scale. This was only measured after TESE and not before and therefore it is unclear if this depression is a consequence of the TESE procedure or a cause of the ED. Risk of decrease in testis volume after TESE One of the signs associated with hypogonadism is a decrease in testis volume. Five studies reported on this sign before and after TESE (Altinkilic et al., 2017; Okada et al., 2002; Ozturk et al., 2011; Schill et al., 2003; Westlander et al., 2001). Because all studies used different time-points and TESE techniques, we were not able to combine the data. Therefore, we will describe these studies one by one. One study measured testicular volume in 35 men with NOA and OA after TESA (Westlander et al., 2001). Here the testis is punctured with a 19-gauge needle with suction, to retrieve sperm. The aspiration was performed 3–5 times per testis. Three months after TESA the mean volume was the same as before TESA. In the second study, a 0.3 and 0.6 ml decrease in mean testicular volume 3 and 12 months after microdissection TESE, respectively, was found (Ozturk et al., 2011). In the 37 men with NOA included in this study, the amount of biopsied tissue was determined at the surgery site and biopsies were taken until it was thought more biopsies would impair the blood supply. The third study evaluated testicular volume in men undergoing conventional TESE (n = 40, including men with NOA, OA and Klinefelter) or microdissection TESE (n = 80, including men with NOA, OA and Klinefelter) (Okada et al., 2002). Measurements of testicular volume were performed at 2 weeks, 1 month and 6 months after TESE but only the data of 6 months after TESE of 120 men were reported. Six months after TESE a decreased testicular volume of at least 2 ml was observed in 25% of the men after conventional TESE and in 2.5% of the men after microdissection TESE. The amount of tissue removed in microdissection TESE was comparable of that of the conventional TESE and ranged between 100 and 300 mg. The fourth study measured the testicular volume on average 18 months after TESE in 39 men (Schill et al., 2003). An increase of 4.3 ml in volume is described. However, the volume was measured in only 26 men before TESE. The fifth study measured the bilateral change in testicular volume 6 weeks after the surgery in 67 men with NOA, OA or Klinefelter (Altinkilic et al., 2017). At this time point, the mean testicular volume was decreased with a difference of 1.5–1.9 ml for, respectively, right or left testis but it is not described if the TESE procedure was performed left, right or bilateral. The volume of the biopsies was not reported. Taken together, although different results were found in each study, three out of five studies show a decrease in testicular volume 6 weeks to 12 months after TESE. The study that did not see any changes was the only study performing TESA (Westlander et al., 2001). Another study that reported an increase in the testicular volume after TESE did not measure the testis volume in all men before TESE. Discussion In this review we evaluated hypogonadism in men with azoospermia after TESE surgery and showed that few high quality data are available from literature. We found there is a temporary decrease in serum total testosterone levels after TESE, for at least 1 year, with levels that may decrease below 12 nmol/l, a threshold level for risk of becoming hypogonadal. The available information on signs and symptoms of hypogonadism after TESE suggests that some men may experience ED, together with depression and anxiety, and a decrease in testicular size. Testosterone as a measure for hypogonadism All included studies presented data on serum total testosterone, one of the measures to determine hypogonadism. The decrease in mean serum total testosterone levels was most profound 6 months after TESE and recovered again to baseline levels after 18 months in men with NOA as well as in men with Klinefelter syndrome. Overall, we saw a greater effect of TESE on mean total testosterone levels in men with Klinefelter syndrome compared to men with NOA. Men with Klinefelter syndrome have decreased basal testosterone levels during and after puberty (Rohayem et al., 2016). Because of their low baseline levels, these men might be more sensitive to a decrease in testosterone levels after TESE. Another explanation is that in men with Klinefelter syndrome the testicular volume is small (Rohayem et al., 2016). Because of this smaller testis the percentage of tissue removed during the TESE biopsy is relatively high compared to men with a bigger testis and subsequently the area of tissue that is damaged will be higher. Interpretation of the consequence of low testosterone levels is not straightforward in view of the different cut-off values suggested by different professional societies and expert groups. According to the Endocrine Society, levels lower than 10.4 nmol/l can be regarded as associated with hypogonadism (Bhasin et al., 2010). On the other hand, the European Association of Urology suggests that levels below 12 nmol/l are associated with symptoms related to hypogonadism (Dohle et al., 2015). At 6 months after TESE, the mean total testosterone levels of men with Klinefelter syndrome were 4.5–6.3 nmol/l and for men with NOA, 8.7–16.4 nmol/l. This implies that in men with Klinefelter and in a proportion of men with NOA total testosterone levels drop below the threshold of 12 nmol/l and thus have a risk of developing symptoms and signs associated with hypogonadism after TESE. We expect the highest prevalence of low total testosterone levels 6 months after TESE, because of the fact that we see the most profound decrease in mean total testosterone levels at this time point. Two out of five studies measured the prevalence at 6 months and these two studies found low testosterone levels in 53 and 5% of the men (Manning et al., 1998; Okada et al., 2002). However, Manning et al. (1998) did not report the threshold used, while Okada et al. (2002) used a very low threshold of 4.9 nmol/l. The other studies that measured prevalence of low testosterone used a follow-up time varying from 1 to 26 months after TESE. Clinical signs and symptoms of hypogonadism Patients will experience hypogonadism by their symptoms rather than on serum testosterone levels. Although cut-off values of serum testosterone levels help to diagnose hypogonadism after TESE, it is not clear whether the TESE-induced decrease in total testosterone levels, irrespective of the levels of serum total testosterone before TESE, might lead to hypogonadism. Therefore, symptoms are more clinically relevant in order to diagnose patients for hypogonadism. New-onset ED was measured in 13 out of 66 men at 6 months after TESE. This was accompanied by a significant decrease in mean total testosterone levels below 12 nmol/l. This suggests that ED after TESE might be explained by hypogonadism, although we cannot exclude that ED is caused by psychological reasons instead of decreased total testosterone levels. ED was especially found in the group of men with unsuccessful sperm retrieval, depression and anxiety, and these factors may have resulted in the ED. However, depression and anxiety can, in addition to causing ED, also be symptoms of hypogonadism. Another possible explanation of the higher prevalence of ED in the group with unsuccessful sperm retrieval is that possibly more biopsies are taken from these men. This might contribute to a higher risk of a decrease in testosterone levels and therefore ED (Manning et al., 1998). An effect of TESE on testicular volume was seen in studies at 6 weeks to 12 months after the procedure, although this effect was less after microdissection TESE. When longer follow-up was reported, no effect was seen of TESE or TESA on testicular volume. This suggests that timing of the follow-up is important. Strengths of this systematic review This review is the first to combine all the reported data on TESE-induced hypogonadism. Because we were able to pool data from these studies, leading to a cohort of 54 men with Klinefelter syndrome and 252 men with NOA, we can conclude that serum total testosterone levels decrease after TESE surgery to levels that might be related to symptoms and signs for hypogonadism. This was supported by the prevalence of new-onset ED and the occurrence of decreased testicular volume after TESE. This information can be taken into account in counselling and follow-up of the men with azoospermia after TESE. Limitations in the interpretation First and foremost, the data are limited by the low number of studies and, in addition, the small size of the available cohorts. Furthermore, most studies only reported on serum total testosterone levels. Strikingly, although TESE is routinely applied, there are only follow-up data available for 54 men with Klinefelter and 252 men with NOA, suitable for our meta-analysis. Because not all studies used the same follow-up time after TESE, these numbers are not representative for all time-points. Furthermore, although more data on total testosterone levels after TESE were available, not all studies reported the data separately for men with different types of azoospermia. Therefore, we could not use all the studies in these analyses. In addition, we had to exclude the largest study because no SDs were described in this study (Ramasamy et al., 2005); however, the results of this study are in line with our results of the meta-analysis.The effect of TESE on decreased total testosterone levels is based on mean total testosterone levels and, because of this, the observed effects may be an underestimation in individuals. A decrease in total testosterone levels in individuals could be missed when looking at the mean levels of a cohort. Therefore, normal mean total testosterone levels do not rule out the presence of men with total testosterone levels below 12 nmol/l that are at risk for symptoms of hypogonadism. Although we were able to do a separate analysis for men with Klinefelter syndrome and men with NOA, we were not able to study the group of men with OA with the available data. It is possible that the risk of hypogonadism differs between various causes of subfertility. In line with this it was shown that the prevalence of low testosterone levels in general in men with NOA is reported to be 45%, while in men with OA this is 16.7% (Sussman et al., 2008). In addition, lower testosterone baseline levels for men with maturation arrest and Sertoli cell only syndrome were found compared to men with hypospermatogenesis (Takada et al., 2008). Therefore, heterogeneity in the mixed population studied might be a potential source of bias. As a results of this possible bias, we tried to separate these data where possible. In addition we were not able to analyse separately the data for various TESE techniques. While in the conventional/open biopsy technique biopsies are taken randomly from different areas of the testis, in the microdissection TESE the location of the biopsies are determined in a more directed way, with the use of a microscope. Therefore, it might be easier to avoid damage caused by destruction of blood vessels and for that reason it is thought microdissection TESE could cause less damage (Shin and Turek, 2013). With TESA and trucut needle testicular biopsy, a needle is used to puncture the tissue, with or without first puncturing the skin with a scalpel, followed by suction of cells and small pieces of tissue. Although the area of damage might be less when using a needle, the location is less well identified. In the three studies comparing the decrease in total testosterone levels after conventional TESE with that after microdissection TESE, the risk was higher or comparable for conventional TESE (Komori et al., 2004; Okada et al., 2002; Ramasamy et al., 2005). Although the TESE technique is reported as conventional or microdissection TESE, the details of the procedure itself will vary at different institutions. These differences in the TESE procedure might increase the heterogeneity of the data between the studies. Biological interpretations of the evidence The effect of TESE on total testosterone can be explained by different mechanisms. The first explanation is that part of the testicular tissue is removed resulting in a lower number of Leydig cells and therefore a lower production of testosterone. However, with decreased serum testosterone levels, the remaining Leydig cells will be stimulated by higher LH levels due to the negative feedback in the hypothalamus–pituitary–gonad axis, and they should become more active in producing testosterone. Nevertheless, it has been shown that stimulation of Leydig cells with hCG after TESE in men with low testosterone levels showed an adequate response, with increased testosterone levels 3 and 4 days after hCG injection. Therefore, these Leydig cells are able to produce more testosterone when they are stimulated, suggesting that in these men a more systemic cause of low LH levels could underlie the hypogonadism after TESE. Indeed, when LH was upregulated immediately after TESE a faster recovery than 18 months was likely expected. Although some studies showed an increase in LH levels after TESE, the normal correlation between LH and total testosterone was not always observed. In one study high LH levels and normal testosterone levels were found in men with NOA and OA (Ishikawa et al., 2009). This combination of high LH and normal testosterone levels is called compensated hypogonadism and might lead to hypogonadism in the future (Tajar et al., 2010). At this point Leydig cells need a higher stimulation to be able to produce normal testosterone levels. However, the number of reports on LH concentrations in relation to testosterone concentrations after TESE is limited and further research would give more insights in the various forms of hypogonadism. A second explanation of the recovery of total testosterone levels is related to the time to repopulate Leydig cells by stem Leydig cells and therefore restore testosterone production at 18 month after TESE. In the rat testis it takes 21 days for new adult Leydig cells to appear from stem Leydig cells after they were chemically destroyed (Jackson et al., 1986). For human Leydig cells, we expect this to be longer than 21 days, however, it is unknown what the exact time span is for human Leydig cells to repopulate the testis. A third and more likely possibility is that the number and function of the Leydig cells is not the cause of decreased total testosterone levels after TESE, but that this is induced by vascular damage in the testis. This vascular damage can result in lower stimulation of Leydig cells by LH because it cannot reach the Leydig cells efficiently, or testosterone is produced in the testis at normal levels but cannot be released into the blood circulation. Indeed, several studies have reported ultrasound findings after TESE and document hypoechoic focal lesions, suggesting haematoma up to 1 and 3 months after TESE, and hyporechoic foci suggestive of scar tissue at 3 and 6 months after TESE (Donoso et al., 2007). Conclusion Although limited studies were obtained from our systematic search, based on the extracted data we found transient but significantly decreased total testosterone levels after TESE that recover to baseline levels after 18–26 months. This effect was most profound in men with Klinefelter syndrome. The number of studies reporting on symptoms and signs of hypogonadism associated with TESE is very limited, showing some risk of ED, which seems to be related to a decreased total testosterone and/or possible depression and anxiety. Furthermore, a decrease in testicular volume is seen in some men after TESE. For better counselling of TESE patients on the transient hypogonadism after TESE, more research is necessary to understand whether the decreased total testosterone is accompanied by symptoms and signs of hypogonadism in the short and long term. It is striking that these data are still not available 25 years after the clinical introduction of TESE. Supplementary data Supplementary data are available at Human Reproduction Update online. Acknowledgements We thank the corresponding authors of included studies who provided additional information on their data upon our request. Authors’ roles J.E. performed the literature search, data extraction and took the lead in writing the manuscript. J.E. and A.v.P. selected the studies. J.E. and M.v.W. performed risk of bias assessment and M.v.W. provided statistical support and performed the meta-regression analysis. All authors took part in the design of the study and writing and revising several drafts of the article. Funding This study was funded by the Academic Medical Center and no external funding was either sought or obtained for this study. Conflict of interest The authors report no financial or other conflict of interest relevant to the subject of this article. References Akbal C , Mangir N , Tavukçu HH , Özgür Ö , Şimşek F . Effect of testicular sperm extraction outcome on sexual function in patients with male factor infertility . Urology 2010 ; 75 : 598 – 601 . Google Scholar CrossRef Search ADS PubMed Altinkilic B , Pilatz A , Diemer T , Wolf J , Bergmann M , Schönbrunn S , Ligges U , Schuppe H-C , Weidner W . Prospective evaluation of scrotal ultrasound and intratesticular perfusion by color-coded duplex sonography (CCDS) in TESE patients with azoospermia . World J Urol 2017 ; 36 : 125 – 133 . Google Scholar CrossRef Search ADS PubMed Bhasin S , Cunningham GR , Hayes FJ , Matsumoto AM , Snyder PJ , Swerdloff RS , Montori VM . Testosterone therapy in adult men with androgen deficiency syndromes: An Endocrine Society Clinical Practice Guideline . J Clin Endocrinol Metab 2010 ; 95 : 2536 – 2559 . http://www.ncbi.nlm.nih.gov/pubmed/20525905%5Cnhttp://press.endocrine.org/doi/full/10.1210/jc.2009-2354. Google Scholar CrossRef Search ADS PubMed Bhasin S , Pencina M , Jasuja GK , Travison TG , Coviello A , Orwoll E , Wang PY , Nielson C , Wu F , Tajar A et al. . Reference ranges for testosterone in men generated using liquid chromatography tandem mass spectrometry in a community-based sample of healthy nonobese young men in the framingham heart study and applied to three geographically distinct cohorts . J Clin Endocrinol Metab 2011 ; 96 : 2430 – 2439 . Google Scholar CrossRef Search ADS PubMed Binsaleh S , Alhajeri D , Madbouly K . Microdissection testicular sperm extraction in men with nonobstructive azoospermia: experience of King Saud University Medical City, Riyadh, Saudi Arabia . Urol Ann 2017 ; 9 : 136 – 140 . Google Scholar CrossRef Search ADS PubMed Bobjer J , Naumovska M , Giwercman YL , Giwercman A . High prevalence of androgen deficiency and abnormal lipid profile in infertile men with non-obstructive azoospermia . Int J Androl 2012 ; 35 : 688 – 694 . Google Scholar CrossRef Search ADS PubMed Bocca S , Moussavi V , Brugh V , Morshedi M , Stadtmauer L , Oehninger S . ICSI outcomes in men undergoing TESE for azoospermia and impact of maternal age . Andrologia 2017 ; 49 . 10.1111/and.12617 . Bourne H , Watkins W , Speirs A , Baker HW . Pregnancies after intracytoplasmic injection of sperm collected by fine needle biopsy of the testis . Fertil Steril 1995 ; 64 : 433 – 436 . http://www.ncbi.nlm.nih.gov/pubmed/7615125. Google Scholar CrossRef Search ADS PubMed Chan PT , Schlegel PN . Nonobstructive azoospermia . Curr Opin Urol 2000 ; 10 : 617 – 624 . Google Scholar CrossRef Search ADS PubMed Cissen M , Meijerink AM , D’Hauwers KW , Meissner A , Van Der Weide N , Mochtar MH , De Melker AA , Ramos L , Repping S , Braat DDM et al. . Prediction model for obtaining spermatozoa with testicular sperm extraction in men with non-obstructive azoospermia . Hum Reprod 2016 ; 31 : 1934 – 1941 . Google Scholar CrossRef Search ADS PubMed Corona G , Pizzocaro A , Lanfranco F , Garolla A , Pelliccione F , Vignozzi L , Ferlin A , Foresta C , Jannini EA , Maggi M et al. . Sperm recovery and ICSI outcomes in Klinefelter syndrome: a systematic review and meta-analysis . Hum Reprod Update 2017 ; 23 : 265 – 275 . Google Scholar CrossRef Search ADS PubMed Craft I , Bennett V , Nicholson N . Fertilising ability of testicular spermatozoa . Lancet 1993 ; 342 : 864 . Google Scholar CrossRef Search ADS PubMed Deruyver Y , Vanderschueren D , Van der Aa F . Outcome of microdissection TESE compared with conventional TESE in non-obstructive azoospermia: a systematic review . Andrology 2014 ; 2 : 20 – 24 . Google Scholar CrossRef Search ADS PubMed Dohle GR , Arver S , Bettocchi C , Jones TH , Kliesch S , Punab M . Male hypogonadism. 2015 . Donoso P , Tournaye H , Devroey P . Which is the best sperm retrieval technique for non-obstructive azoospermia? A systematic review . Hum Reprod Update 2007 ; 13 : 539 – 549 . Google Scholar CrossRef Search ADS PubMed Esteves SC . Serial ultrasonography, hormonal profile and antisperm antibody response after testicular sperm aspiration: editorial comment . Int Braz J Urol 2002 ; 28 : 167 – 168 . Esteves S , Agarwal A . Reproductive outcomes, including neonatal data, following sperm injection in men with obstructive and nonobstructive azoospermia: case series and systematic review . Clinics 2013 ; 68 : 141 – 149 . http://clinics.org.br/article.php?id=1000. Google Scholar CrossRef Search ADS PubMed Everaert K , De Croo I , Kerckhaert W , Dekuyper P , Dhont M , Van der Elst J , De Sutter P , Comhaire F , Mahmoud A , Lumen N . Long term effects of micro-surgical testicular sperm extraction on androgen status in patients with non obstructive azoospermia . BMC Urol 2006 ; 6 : 9 . Google Scholar CrossRef Search ADS PubMed Ishikawa T , Yamaguchi K , Chiba K , Takenaka A , Fujisawa M . Serum Hormones in patients with nonobstructive azoospermia after microdissection testicular sperm extraction . J Urol 2009 ; 182 : 1495 – 1499 . 10.1016/j.juro.2009.06.029 Google Scholar CrossRef Search ADS PubMed Jackson AE , O’Leary PC , Ayers MM , Kretser DM . The effects of ethylene dimethane sulphonate (EDS) on rat Leydig cells: evidence to support a connective tissue origin of Leydig cells . Biol Reprod 1986 ; 35 : 425 – 437 . Google Scholar CrossRef Search ADS PubMed Jungwirth A , Diemer T , Dohle GR , Giwercman A , Kopa Z , Krausz C , Turnaye H . Guidelines on male infertility . Eur Urol 2015 ; 62 : 324 – 332 . Google Scholar CrossRef Search ADS Komori K , Tsujimura A , Miura H , Shin M , Takada T , Honda M , Matsumiya K , Fujioka H . Serial follow-up study of serum testosterone and antisperm antibodies in patients with non-obstructive azoospermia after conventional or microdissection testicular sperm extraction . Int J Androl 2004 ; 27 : 32 – 36 . Google Scholar CrossRef Search ADS PubMed Manning M , Jünemann KP , Alken P . Decrease in testosterone blood concentrations after testicular sperm extraction for intracytoplasmic sperm injection in azoospermic men . Lancet 1998 ; 352 : 37 . Google Scholar CrossRef Search ADS PubMed Meijerink AM , Cissen M , Mochtar MH , Fleischer K , Thoonen I , De Melker AA , Meissner A , Repping S , Braat DDM , VanWely M et al. . Prediction model for live birth in ICSI using testicular extracted sperm . Hum Reprod 2016 ; 31 : 1942 – 1951 . Google Scholar CrossRef Search ADS PubMed Okada H , Dobashi M , Yamazaki T , Hara I , Fujisawa M , Arakawa S , Kamidono S . Conventional versus microdissection testicular sperm extraction for nonobstructive azoospermia . J Urol 2002 ; 168 : 1063 – 1067 . Google Scholar CrossRef Search ADS PubMed Ozturk U , Ozdemir E , Dede O , Sagnak L , Goktug HNG , Gurbuz OA , Cagatay M , Imamoglu MA . Assessment of anti-sperm antibodies in couples after testicular sperm extraction . Clin Investig Med 2011 ; 34 : 179 – 184 . Google Scholar CrossRef Search ADS Ramasamy R , Yagan N , Schlegel PN . Structural and functional changes to the testis after conventional versus microdissection testicular sperm extraction . Urology 2005 ; 65 : 1190 – 1194 . Google Scholar CrossRef Search ADS PubMed Rohayem J , Nieschlag E , Zitzmann M , Kliesch S . Testicular function during puberty and young adulthood in patients with Klinefelter’s syndrome with and without spermatozoa in seminal fluid . Andrology 2016 ; 4 : 1178 – 1186 . Google Scholar CrossRef Search ADS PubMed Schill T , Bals-Pratsch M , Küpker W , Sandmann J , Johannisson R , Diedrich K . Clinical and endocrine follow-up of patients after testicular sperm extraction . Fertil Steril 2003 ; 79 : 281 – 286 . Google Scholar CrossRef Search ADS PubMed Schlegel PN , Li PS . Microdissection TESE: sperm retrieval in non-obstructive azoospermia . Hum Reprod Updat 1998 ; 4 : 439 . http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9825858. Google Scholar CrossRef Search ADS Schlegel PN , Su LM . Physiological consequences of testicular sperm extraction . Hum Reprod 1997 ; 12 : 1688 – 1692 . Google Scholar CrossRef Search ADS PubMed Schoysman R , Vanderzwalmen P , Nijs M , Segal L , Segal-Bertin G , Geerts L , van Roosendaal E , Schoysman D . Pregnancy after fertilisation with human testicular spermatozoa . Lancet 1993 ; 342 : 1237 . Google Scholar CrossRef Search ADS PubMed Shin DH , Turek PJ . Sperm retrieval techniques . Nat Rev Urol 2013 ; 10 : 723 – 730 . Google Scholar CrossRef Search ADS PubMed Steele EK , Ellis PK , Lewis SEM , McClure N . Ultrasound, antisperm antibody, and hormone profiles after testicular Trucut biopsy . Fertil Steril 2001 ; 75 : 423 – 428 . Google Scholar CrossRef Search ADS PubMed Sterne JA , Hernán MA , Reeves BC , Savović J , Berkman ND , Viswanathan M , Henry D , Altman DG , Ansari MT , Boutron I et al. . ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions . Br Med J 2016 ; 355 : i4919 . Google Scholar CrossRef Search ADS Sussman EM , Chudnovsky A , Niederberger CS . Hormonal evaluation of the infertile male: has it evolved? Urol Clin North Am 2008 ; 35 : 147 – 155 . Google Scholar CrossRef Search ADS PubMed Tajar A , Forti G , O’Neill TW , Lee DM , Silman AJ , Finn JD , Bartfai G , Boonen S , Casanueva FF , Giwercman A et al. . Characteristics of secondary, primary, and compensated hypogonadism in aging men: evidence from the European male ageing study . J Clin Endocrinol Metab 2010 ; 95 : 1810 – 1818 . Google Scholar CrossRef Search ADS PubMed Takada S , Tsujimura A , Ueda T , Matsuoka Y , Takao T , Miyagawa Y , Koga M , Takeyama M , Okamoto Y , Matsumiya K et al. . Androgen decline in patients with nonobstructive azoospemia after microdissection testicular sperm extraction . Urology 2008 ; 72 : 114 – 118 . Google Scholar CrossRef Search ADS PubMed The Prisma Group from Moher D, Liberati A, Tetzlaff J, AD . Preferred reporting items for systematic reviews and meta analyses: The Prisma Statement . PLoS Med 2009 ; 6 : 1 – 15 . www.prisma-ststement.org. CrossRef Search ADS Van Peperstraten A , Proctor ML , Johnson NP , Philipson G . Techniques for surgical retrieval of sperm prior to intra-cytoplasmic sperm injection (ICSI) for azoospermia . Cochrane Database Syst Rev 2008 ; CD002807 . Van Wely M , Barbey N , Meissner A , Repping S , Silber SJ . Live birth rates after MESA or TESE in men with obstructive azoospermia: is there a difference? Hum Reprod 2015 ; 30 : 761 – 766 . Google Scholar CrossRef Search ADS PubMed Wang C , Nieschlag E , Swerdloff R , Behre HM , Hellstrom WJ , Gooren LJ , Kaufman JM , Legros JJ , Lunenfeld B , Morales A et al. . Investigation, treatment, and monitoring of late-onset hypogonadism in males: ISA, ISSAM, EAU, EAA, and ASA Recommendations . Eur Urol 2009 ; 55 : 121 – 130 . Google Scholar CrossRef Search ADS PubMed Westlander G , Ekerhovd E , Granberg S , Lycke N , Nilsson L , Werner C , Bergh C . Serial ultrasonography, hormonal profile and antisperm antibody response after testicular sperm aspiration . Hum Reprod 2001 ; 16 : 2621 – 2627 . Google Scholar CrossRef Search ADS PubMed Zitzmann M , Faber S , Nieschlag E . Association of specific symptoms and metabolic risks with serum testosterone in older men . J Clin Endocrinol Metab 2006 ; 91 : 4335 – 4343 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Human Reproduction Update Oxford University Press

The risk of TESE-induced hypogonadism: a systematic review and meta-analysis

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Oxford University Press
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© The Author(s) 2018. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.
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1355-4786
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1460-2369
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10.1093/humupd/dmy015
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Abstract

Abstract BACKGROUND Testicular sperm extraction (TESE) is a surgical procedure to retrieve spermatozoa from the testes of men with azoospermia to help them achieve biological parenthood. Although effective, the surgical procedure is not without complications and haematoma, devascularization, inflammation and a decrease in testosterone levels have been described as such. The prevalence and duration of hypogonadism and associated symptoms after TESE have not been studied systematically. OBJECTIVE AND RATIONALE In this systematic review we addressed the following research questions: Are serum testosterone levels decreased after TESE and, if so, do these levels recover over time? What is the prevalence of symptoms and signs related to hypogonadism after TESE and are they related to testosterone levels? SEARCH METHODS We searched the databases Pubmed and Embase from 1 January 1993 to 26 June 2017. We combined subject headings with terms in title and/or abstract for participants, intervention and outcomes. We included all studies that reported on TESE, regardless of the specific technique used, that measured testosterone and/or LH, and/or had information on signs or symptoms related to hypogonadism as defined by hypogonadism guidelines. An additional inclusion criterion was that studies described these measurements both before and after TESE. The quality of the included studies was assessed using the Risk Of Bias In Non-randomized Studies—of Interventions tool. OUTCOMES We identified 15 studies reporting on total testosterone levels of which five studies also reported on testicular volume and one study on erectile dysfunction. Men with Klinefelter syndrome and men with non-obstructive azoospermia had the strongest decrease in total testosterone levels 6 months after TESE, with a mean decrease of 4.1 and 2.7 nmol/l, respectively, which recovered again to baseline levels 26 and 18 months after TESE, respectively. At 6 months after TESE, some studies reported serum total testosterone concentrations below a cut-off value of 12 nmol/l, where symptoms and signs related to hypogonadism may appear. Furthermore, an increased prevalence of erectile dysfunction related to decreased total testosterone levels 6 months after TESE was reported. Also, in some men a decrease in testicular volume was reported. However, it is not clear if this is related to low testosterone levels. WIDER IMPLICATIONS The transient, but statistically significant, decrease in total testosterone levels indicates that men are at risk of developing a temporary hypogonadism after TESE, but there is insufficient evidence for whether patients actually experience clinical symptoms in case of decreased serum testosterone levels. To be able to properly counsel TESE patients, more large-scale monitoring on signs and symptoms of hypogonadism, in combination with testosterone measurements, needs to be performed in men undergoing TESE. testosterone, azoospermia, assisted reproduction, testicular sperm extraction, hypogonadism, erectile dysfunction, non-obstructive azoospermia, Klinefelter syndrome, sperm retrieval Introduction Testicular sperm extraction (TESE) is a surgical procedure to assist men with azoospermia to achieve biological parenthood. With this technique spermatozoa can be retrieved directly from the testicular tissue and subsequently used for ICSI. In 1993, the first successful fertilization, and soon after that the first pregnancy, with testicular sperm after ICSI were described (Craft et al., 1993; Schoysman et al., 1993). Since then, the technique developed further and at present various TESE techniques have been reported, such as multibiopsy/conventional TESE, microdissection TESE and testicular sperm aspiration (TESA) (Craft et al., 1993; Bourne et al., 1995; Schlegel and Li, 1998). Evidence that one technique should be preferred over the other based on sperm retrieval rates, pregnancy rates, live birth rates and complications are limited (Donoso et al., 2007; Van Peperstraten et al., 2008). Although a higher sperm retrieval rate is described for men with non-obstructive azoospermia (NOA) after microdissection TESE compared to conventional TESE, this is not true for all men and depends on the type and cause of azoospermia (Deruyver et al., 2014). Currently, TESE is the only possible therapy for men with NOA to obtain spermatozoa to father their own genetic children. In case of obstructive azoospermia (OA), microsurgical epididymal sperm aspiration or percutaneous epididymal sperm aspiration is the preferred method to retrieve spermatozoa (Van Wely et al., 2015). If unsuccessful, a subsequent TESE procedure could also be offered to these men. TESE is now routinely offered worldwide to men with azoospermia with a success rate of retrieval of spermatozoa of ~50% for men with NOA and Klinefelter syndrome, and can go up to 100% for men with OA (Chan and Schlegel, 2000; Cissen et al., 2016; Corona et al., 2017). The described live birth rates for ICSI with testicular retrieved spermatozoa vary from 10 to 45% per cycle for all types of azoospermia (Bocca et al., 2017; Corona et al., 2017; Esteves and Agarwal, 2013; Meijerink et al., 2016). In the TESE procedure a small biopsy of testicular tissue is obtained via dissection followed by tissue resection, while with TESA small pieces of tissue are aspirated to extract spermatozoa. Post-operative complications, such as haematoma, devascularisation and inflammation, have been described, eventually leading to scars and calcification (Schlegel and Su, 1997; Donoso et al., 2007). Furthermore, a decrease in serum testosterone levels after a TESE procedure has been described (Donoso et al., 2007; Shin and Turek, 2013). Decreased testosterone levels can subsequently lead to hypogonadism. Symptoms of hypogonadism have been described to occur more often when total testosterone levels are below a threshold of 12 nmol/l, and the lower the total testosterone values, the more frequent the symptoms of hypogonadism will be present (Bhasin et al., 2011; Dohle et al., 2015; Zitzmann et al., 2006). According to various guidelines on hypogonadism, the diagnosis is based on the presence of one or more signs or symptoms. Symptoms can be—among others—erectile dysfunction (ED), decreased muscle strength and loss of libido. Additional signs, for example, decrease in bone mineral density and a decrease in testicular volume can occur (Table I) (Wang et al., 2009; Bhasin et al., 2010; Jungwirth et al., 2015). Because many of these clinical manifestations are not specific for hypogonadism, the diagnosis should always be confirmed by measuring serum testosterone levels (Bhasin et al., 2010; Dohle et al., 2015). Table I Signs and symptoms associated with androgen deficiency in men. Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia Table I Signs and symptoms associated with androgen deficiency in men. Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia Small testes/shrinking testes Erectile dysfunction/decreased spontaneous erections/fewer and diminished nocturnal erections Gynaecomastia/breast discomfort Decrease in lean body mass and muscle strength/reduced muscle bulk Visceral obesity/increased body fat, BMI Decrease in bone mineral density (osteoporosis) with low trauma fractures/height loss Reduced sexual desire and sexual activity/reduced libido Decreased body hair/loss of body (axillary and pubic) hair Hot flushes/sweats Changes in mood and anger/decreased motivation, initiative, and self-confidence, feeling sad or blue, depressed mood, dysthymia Decreased energy/fatigue/sleep disturbances/increased sleepiness Metabolic syndrome Insulin resistance and type-2 diabetes mellitus Diminished cognitive function/poor concentration and memory, diminished physical or work performance Mild anaemia The prevalence and duration of hypogonadism and associated symptoms as a result of the TESE procedure have not been studied systematically. This information is necessary to properly counsel men who qualify for TESE on the potential risk of developing hypogonadism after TESE. We therefore systematically reviewed the literature and included all studies that measured testosterone levels, LH levels and/or signs and symptoms related to hypogonadism before and after TESE. In this systematic review we addressed the following research questions: Are serum total testosterone levels decreased after TESE and, if so, do these levels recover over time? What is the prevalence of symptoms and signs related to hypogonadism after TESE and are they related to total testosterone levels? Methods This review is reported according to the PRISMA statement (The Prisma Group from Moher D, Liberati A, Tetzlaff J, 2009). Prior to the search, a plan regarding the study design, search methods and inclusion and exclusion criteria was written and approved by all authors. We registered the protocol at Prospero with registration number CRD42016052596 and is available from http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42016052596. Search and study selection We searched the databases Pubmed and Embase from 1 January 1993, when the first TESE procedure was described, to 26 June 2017. We combined subject headings with terms in title and/or abstract for the intervention, outcomes and participants. The details of the search are displayed in Supplementary Tables SI and SII. Two authors (J.E. and A.v.P.) screened the articles independently on title and abstract for eligibility based on predefined inclusion criteria. Then both authors carefully read the full text independently to further exclude studies which did not meet the inclusion criteria. When there was discrepancy between the authors, articles were discussed until agreement was achieved. Eligibility criteria We included all original English, peer-reviewed articles, irrespective of study-design. There were no restrictions in TESE techniques. We included all studies which measured testosterone, LH, or signs or symptoms related to hypogonadism (Table I), defined according to international hypogonadism guidelines (Bhasin et al., 2010; Dohle et al., 2015; Wang et al., 2009). To assess the association between TESE and hypogonadism and its associated signs and symptoms, we only included the studies that performed the measurements before and after TESE. Furthermore, we excluded studies that included prepubertal boys because of the difference in baseline characteristics and testosterone and LH levels compared to adult men. Data extraction One author (J.E.) extracted data from the included articles. The following data were extracted when available: first author, year of publication, study design, TESE technique, number of participants, age of participants, type of azoospermia, type of outcome and outcome in mean values with SD or prevalence of the outcome. When data of the outcomes were not available we contacted the corresponding authors to ask for the data. If we did not receive the raw data, but they were displayed in graphs, we extracted the data from the graphs. Quality assessment Two authors (J.E. and M.v.W.) assessed the quality of the included studies using the Risk Of Bias In Non-randomized Studies—of Interventions tool (Sterne et al., 2016). With this tool we estimated the risk of bias due to confounding, selection of participants into the study, classification of intervention, deviations from intended interventions, missing data, measurements of outcomes and selection of the reported results. Data analyses To study the effect of TESE on testosterone levels over time we used the mean testosterone levels from individual studies to perform meta-regression analyses using STATA 14.2 software (StataCorp, College Station, TX, USA). Where possible we identified different patient groups based on their type of azoospermia, namely, men with OA, men with NOA and men with Klinefelter syndrome. To calculate the individual odds ratios (OR) and individual and pooled mean differences with corresponding 95% CI we used Review Manager 5.3 (The Cochrane Collaboration, The Nordic Cochrane Centre, Copenhagen, Denmark). Binary outcomes were expressed as OR and continuous outcomes as mean differences. To calculate mean differences we compared the outcomes after TESE with outcomes before TESE. A random effect model was standardly applied. Data were pooled based on the patient groups described above and on follow-up time. We classified follow-up time of 1–3 months as short term, 6 months as intermediate, 9–12 months as intermediate-long, and when the follow-up was more than 12 months this was classified as long term. Results Study selection With our systematic search we identified 611 reports from PubMed and 1011 from Embase. After removing duplicates, 1255 reports remained for screening of eligibility in title and abstract. Based on our inclusion criteria, we included 47 reports for reading the full text, of which we excluded 32 studies that did not meet the inclusion criteria. Eventually, we included 15 studies for our systematic review. The corresponding flowchart is depicted in Fig. 1. Figure 1 View largeDownload slide Flowchart of the search and selection of literature on induced hypogonadism after testicular sperm extraction in men. TESE, testicular sperm extraction. Figure 1 View largeDownload slide Flowchart of the search and selection of literature on induced hypogonadism after testicular sperm extraction in men. TESE, testicular sperm extraction. Study characteristics All 15 included studies reported on serum levels of total testosterone before and after TESE. Nine studies also reported serum LH levels and six studies reported on symptoms or signs of hypogonadism in addition to the hormone levels (Table II). The 15 studies were published between 1998 and 2017. The study with the smallest number of patients included 15 men and the study with the largest number of patients included 435 men, although they only reported testosterone levels before and after TESE from 142 men. The age of the men varied between 25 and 61 years. In all studies men with NOA were included; five studies also included men with OA and eight studies also included men with Klinefelter syndrome. In some of these studies the data for the various types of azoospermia were not separated. The TESE techniques used varied between studies (TESA, multiple biopsy/conventional, microdissection TESE and Trucut needle). The follow up of the men varied between 1 month and 46 months after TESE. Table II Basic characteristics of studies on testicular sperm extraction included in this review. Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH *Data not described separately for the different patient groups. TESE, testicular sperm extraction; NOA, non-obstructive azoospermia; OA, obstructive azoospermia; KF, Klinefelter syndrome. Table II Basic characteristics of studies on testicular sperm extraction included in this review. Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH Study characteristics Intervention Patient characteristics Outcome First author Year Study design TESE technique Size biopsy Number participants Age (years: mean ± SD (range)) Type azoospermia Type of measurement Manning 1998 Cohort Multiple biopsy TESE Not described 15 Not reported NOA Testosterone Westlander 2001 Prospective cohort TESA Not described 35 33.3 ± 5.52 (26–48) NOA (n = 10) and OA (n = 25)* Testosterone Testicular volume Steele 2001 Prospective cohort Trucut needle testicular biopsy Not described 20 Not reported NOA and OA* Testosterone LH Okada 2002 Retrospective cohort Conventional TESE 150–450 mg 146 Not reported NOA (n = 18), KF (n = 6) and OA (n = 22)* Testosterone Microdissection TESE 100–450 mg NOA (n = 63), KF (n = 11) and OA (n = 26)* Testicular volume Schill 2003 Prospective cohort Open biopsy TESE Two biopsies 40 36 (29–53) NOA (n = 31) and OA (n = 9)* Testosterone Testicular volume Komori 2004 Cohort Conventional multiple TESE 150 mg 25 35.4 ± 6.4 (29–49) NOA (n = 13) Testosterone Microdissection TESE 60–120 mg 31.8 ± 4.7 (27–42) NOA (n = 10) and KF (n = 2)* Ramasamy 2005 Retrospective cohort Conventional multiple biopsy TESE 500 mg 435 38 ± 1 NOA Testosterone Microdissection TESE Not described 36 ± 0.3 LH Everaert 2006 Retrospective cohort Microsurgical TESE Not described 48 34 ± 7 NOA (n = 47 and KF (n = 1)* Testosterone LH Takada 2008 Cohort Microdissection TESE Not described 69 33.9 ± 0.5 years NOA (n = 60) and KF (n = 9) Testosterone LH Ishikawa 2009 Retrospective cohort Microdissection TESE Not described 140 34.8 ± 5.2 (24–57) NOA (n = 100) and KF (n = 40) Testosterone LH Akbal 2010 Cohort Microdissection TESE Not described 66 34.8 (24–53) NOA Testosterone LH Erectile dysfunction Ozturk 2011 Prospective cohort Microdissection TESE Not described 37 32.8 ± 6.7 NOA Testosterone Testicular volume Bobjer 2012 Retrospective cohort Multiple biopsy TESE Not described 45 36 ± 6.3 (25–61) NOA (n = 40) and KF (n = 5) Testosterone LH Altinkilic 2017 Prospective cohort OA: conventional trifocal TESE Not described 78 34 ± 6 NOA (n = 48), KF (n = 6) and OA (n = 24) * Testosterone NOA: combined Not described LH Trifocal/microdissection TESE Testicular volume Binsaleh 2017 Retrospective cohort Microdissection TESE Not described 255 35.8 ± 7.2 NOA (n = 244) KF (n = 11)* Testosterone LH *Data not described separately for the different patient groups. TESE, testicular sperm extraction; NOA, non-obstructive azoospermia; OA, obstructive azoospermia; KF, Klinefelter syndrome. Quality assessment We assessed the risk of bias on confounding as low in all studies since we only included studies comparing data after TESE with that before TESE. We assessed the risk of bias on selection of participants as unclear in studies that did not describe men with OA as a separate group from men with NOA (n = 3), and high in the studies that included men with Klinefelter syndrome together with men with NOA (n = 5). In studies in which men who had undergone TESE for the second or third time were included, we determined the risk of bias on selection of participants as unclear (n = 3). We determined the risk of bias in classification of intervention as unclear in studies in which different TESE techniques were applied but assessed the outcome as one group (n = 2) and in studies in which one testis was biopsied in some men but both testes in others (n = 1). Some studies did not describe all men in the follow up, which we assessed as an unclear (n = 8) or high (n = 4) risk of bias on missing data. We assigned an unclear bias in measurements of outcome to studies that did not report at what time during the day blood samples were taken for hormone levels (n = 4), or studies that did not report cut-off values on low total testosterone (n = 1). In studies that reported a different follow-up time per man we also assessed the risk of bias in measurements of outcome as unclear (n = 3). We assessed the risk of bias selection of reported results as unclear in 13 out of 15 studies (87%). The detailed information on the quality assessed per study can be found in Fig. 2. Figure 2 View largeDownload slide Risk of bias summary for the 15 studies selected from the literature review. Figure 2 View largeDownload slide Risk of bias summary for the 15 studies selected from the literature review. Testosterone levels after TESE From the 15 studies that measured serum total testosterone levels before and after TESE, one study only reported the testosterone levels of the men with new-onset of ED after TESE. In these men, serum total testosterone levels were significantly decreased after TESE (Akbal et al., 2010). Another study reported a decrease of serum testosterone levels 3–6 months after TESE, and a recovery of these levels after 18 months in both microdissection and conventional TESE, but did not report SDs (Ramasamy et al., 2005). We did not include these two studies in our meta-analyses. Mean testosterone levels after TESE Twelve studies compared mean total testosterone levels before and after TESE (Table III). Meta-regression analysis showed a significant decrease in total testosterone levels at 3, 6, 9 and 12 months after TESE compared to before, which recovered to normal values again at 18 months (Fig. 3A). There was a lot of variation in testosterone levels between studies before TESE. To reduce this heterogeneity we analysed two patient groups separately, i.e. men with Klinefelter syndrome (three studies) and men with NOA (five studies). It was not possible to identify separate data for men with OA. Table III Characteristics of studies that measured testosterone levels after TESE. First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels *Not included in meta-regression analysis. Table III Characteristics of studies that measured testosterone levels after TESE. First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels First author (year of publication) Technique testosterone measurement Time of blood samples Time after TESE measured Threshold used for low testosterone levels Number participants with data available Type of outcome Manning (1998) Not described 08.00 AM 6 and 12 months Not described 15 (12 months n = 8) Mean testosterone levels and prevalence low testosterone Westlander (2001) Not described Not described 3 and 6 months Not described 35 Mean testosterone levels Steele (2001) Radioimmunoassay by Coat-A-Count technology. Not described 4 weeks ≤12 nmol/l 8 Mean testosterone levels and individual testosterone levels Okada (2002)* Radioimmunoassay Not described 6 months Significant decrease was defined as: When testosterone level was normal before TESE and after TESE <1.4 ng/ml or a decrease >1 ng/ml for men with hypogonadism before TESE Conventional TESE: n = 40 microdissection TESE: n = 80 Prevalence significant decrease in testosterone levels Schill (2003) Competitive enzyme immunoassay, part of an automatic measuring apparatus, SR1 08.00–10.00 AM Average 18 months (4 to 32) <12 nmol/l Before TESE: n = 26 after TESE: n = 39 Mean testosterone levels and prevalence low testosterone Komori (2004) Not described 09.00–11.00 AM 1, 6 and 12 months Not described Multiple TESE: n = 13 microdissection TESE: n = 12 Mean total testosterone levels Ramasamy (2005)* Not described 07.00–10.00 AM 3, 6, 12 and 18 months Not described 3–6 months: n = 142 12 months: n = 88 18 months: n = 53 Mean testosterone levels Everaert (2006) Radioimmunoassay 08.00–10.00 AM 2.4 years ± 1.1 years <280 ng/dl Before TESE: n = 45 after TESE: n = 31 Mean testosterone levels and number of men with de novo androgen deficiency Takada (2008) Solid-phase [125]I radioimmunoassay kit Coat-A-Count 08.00–11.00 AM 3, 6, and 12 months Not described KF: n = 9 NOA: n = 60 Mean total testosterone levels Ishikawa (2009) Not described 09.00–10:00 AM 1, 3, 6, 9, 12, and 18 months Not described KF: n = 40 NOA: n = 100 Changes in testosterone levels relative to baseline testosterone levels Akbal (2010)* Not described 09.00–11.00 AM 6 months Not described Data of men with new-onset ED: n = 13 Mean total testosterone levels Ozturk (2011) Not described 09.00–11.00 AM 3 and 12 months Not described 37 Mean total testosterone levels Bobjer (2012) Competitive immunoassay Before 11.00 AM Average 2.2 years ± 1.6 (0.2–5.4) ≤10 nmol/l KF: n = 5 NOA: n = 40 Mean testosterone levels and prevalence low testosterone Altinkilic (2017) Not described 08.00–10.00 AM 6 weeks Not described before TESE: n = 78 after TESE: n = 67 Mean testosterone levels Binsaleh (2017) Not described Not reported 3 months and more than 1 year Not described 111 Mean testosterone levels *Not included in meta-regression analysis. Figure 3 View largeDownload slide Overview of mean serum total testosterone levels in men after TESE over time. Total testosterone levels are shown in (A) all men, (B) men with Klinefelter syndrome and (C) men with non-obstructive azoospermia. Figure 3 View largeDownload slide Overview of mean serum total testosterone levels in men after TESE over time. Total testosterone levels are shown in (A) all men, (B) men with Klinefelter syndrome and (C) men with non-obstructive azoospermia. For men with Klinefelter syndrome, in total data for 54 men were available (Takada et al., 2008; Ishikawa et al., 2009; Bobjer et al., 2012). There was a significant decrease in total testosterone levels after TESE, but these levels recovered to baseline values after 26 months (Fig. 3B). In one out of three studies, the mean testosterone levels in men with Klinefelter syndrome were above the threshold for hypogonadism of 12 nmol/l at baseline (Bobjer et al., 2012). The meta-analysis using mean differences shows the strongest mean decrease in total testosterone at 6 months after TESE with a mean decrease of 4.13 nmol/l (95% CI: −5.86, −2.40) (Supplementary Fig. S1A). The mean total testosterone levels rose at long-term follow-up (>12 months) to a mean difference of −2.28 nmol/l (95% CI: −4.03, −0.53), but the total testosterone levels remained significantly lower compared to the levels before TESE. For men with NOA we were able to include five studies with a total of 252 men (Manning et al., 1998; Takada et al., 2008; Ishikawa et al., 2009; Ozturk et al., 2011; Bobjer et al., 2012). In these men we found variations in baseline mean total testosterone levels with some mean total testosterone levels below the threshold for hypogonadism of 12 nmol/l (Fig. 3C). We found the largest decrease in mean total testosterone levels 6 months after TESE, of 2.72 nmol/l (95% CI: −5.02, −0.41) (Supplementary Fig. S1B). Our meta-analysis shows a significant decrease in mean total testosterone levels at 9–12 months after TESE, which disappears at long-term follow-up. In most studies LH levels were associated with testosterone levels; when a decrease in total testosterone was reported, a significant increase in LH was found (Takada et al., 2008; Altinkilic et al., 2017; Binsaleh et al., 2017) and when no decrease in total testosterone was reported, also no increase in LH was found (Steele et al., 2001; Everaert et al., 2006; Bobjer et al., 2012). In one study no decrease in serum testosterone after TESE in men with NOA and OA was reported, but an increase in LH levels after TESE was seen (Ishikawa et al., 2009). In the same study (Ishikawa et al., 2009) in men with Klinefelter syndrome a decrease in testosterone after TESE was reported, but no increase in LH levels. One study examined Leydig cell function by performing an hCG test within a period of 4–32 months after TESE (Schill et al., 2003). Out of 13 men with NOA with low serum testosterone levels measured before or after TESE, three men had insufficient increase in testosterone levels after stimulation with hCG (<1.5-fold increase). In addition, 6 out of 15 men with NOA with normal testosterone levels before and after TESE showed insufficient testosterone increase after hCG stimulation, indicating a disturbed functioning of Leydig cells. Prevalence of low testosterone after TESE Five studies described the prevalence of low total testosterone levels after TESE, using thresholds varying from 5 to 12 nmol/l, or this was not specified. In total, 229 men were involved (Table III). The ORs per study show that there is a trend towards an increased risk for low total testosterone levels after TESE (Fig. 4). Because of the differences in follow-up time and in thresholds used for low testosterone levels, pooling of the data was not informative. Figure 4 View largeDownload slide Forest plot with odds ratio of low total testosterone in men after TESE. Figure 4 View largeDownload slide Forest plot with odds ratio of low total testosterone in men after TESE. Risk of symptoms and signs related to hypogonadism after TESE Our systematic literature search revealed that only six studies reported on symptoms or signs associated with hypogonadism after TESE (Table IV). The reported symptoms and signs are limited to ED (Akbal et al., 2010) and changes in testicular size (Altinkilic et al., 2017; Esteves, 2002; Okada et al., 2002; Ozturk et al., 2011; Schill et al., 2003). Table IV Basic characteristics of studies that measured symptoms or signs related to hypogonadism after TESE. First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml Table IV Basic characteristics of studies that measured symptoms or signs related to hypogonadism after TESE. First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml First author (year of publication) Type of measurement Technique of measurement Time after TESE Number participants with data available Outcome (mean ± SD) Akbal (2010) Erectile dysfunction IIEF-5 questionnaire 6 months 66 Prevalence erectile dysfunction (score < 22) before TESE: 28 out of 66 after TESE: 35 out of 66 However: 13 out of 66 with new-onset ED Westlander (2001) Testicular volume Physical examination 3 months 35 Mean testicular volume before TESE: 17.1 ± 4.24 ml after TESE: 17.1 ± 4.27 ml Okada (2002) Testicular volume Orchidometer 6 months Conventional TESE: 40 microdissection TESE: 80 Prevalence of decrease >2 ml in testicular volume conventional TESE: before TESE: 0 out of 40 6 months: 10 out of 40 microdissection TESE: before TESE: 0 out of 80 6 months: 2 out of 80 Schill (2003) Testicular volume Ultrasound Average 18 months (4–32) Before TESE: 26 after TESE: 39 Mean testicular volume before TESE: 17 ml after TESE: 21.3 ml Ozturk (2011) Testicular volume Physical examination 3 and 6 months 37 Mean testicular volume before TESE: 9.8 ± 1.29 ml 3 months: 9.5 ± 1.35 ml 6 months: 9.2 ± 0.94 ml Altinkilic (2017) Testicular volume Ultrasound 24 h and 6 weeks Before TESE: 78 24 h: 71 6 weeks: 67 Mean testicular volume before TESE left: 8.2 ± 4.2 ml, right: 9 ± 4.8 ml 24 h left: 8.8 ± 4.9 ml, right: 9.4 ± 5.0 ml 6 weeks left: 6.3 ± 3.7 ml, right: 7.5 ± 4.6 ml Risk of ED after TESE The risk of ED after TESE, one of the symptoms of hypogonadism, was described in one study in which 13 out of 66 men with new-onset ED were reported 6 months after TESE (Akbal et al., 2010): men with NOA and undergoing microdissection TESE were included. Overall, 13 men had a score of ≥22 according to the International Index of Erectile Function-5 (IIEF-5) questionnaire, indicating no ED, before TESE and ≤21, indicating ED, after TESE. However, a score of ≤21 was reported in 28 men before TESE and 35 men after TESE, respectively. Although ED was subdivided into mild, moderate and severe depending on the score, no details were reported on the severity of ED in each patient. Out of the 13 men with new-onset ED, one man had successful retrieval of sperm, while from the other 12 men no sperm was retrieved. Hormonal levels were measured in 36 men, but only the data of the 13 men with new-onset ED are reported. In these men the mean total testosterone level was significantly decreased from 27.1 to 9.7 nmol/l. LH was increased in these men, but not significantly. All 13 men reported depression and anxiety after TESE, assessed with the Hospital Anxiety and Depression Scale. This was only measured after TESE and not before and therefore it is unclear if this depression is a consequence of the TESE procedure or a cause of the ED. Risk of decrease in testis volume after TESE One of the signs associated with hypogonadism is a decrease in testis volume. Five studies reported on this sign before and after TESE (Altinkilic et al., 2017; Okada et al., 2002; Ozturk et al., 2011; Schill et al., 2003; Westlander et al., 2001). Because all studies used different time-points and TESE techniques, we were not able to combine the data. Therefore, we will describe these studies one by one. One study measured testicular volume in 35 men with NOA and OA after TESA (Westlander et al., 2001). Here the testis is punctured with a 19-gauge needle with suction, to retrieve sperm. The aspiration was performed 3–5 times per testis. Three months after TESA the mean volume was the same as before TESA. In the second study, a 0.3 and 0.6 ml decrease in mean testicular volume 3 and 12 months after microdissection TESE, respectively, was found (Ozturk et al., 2011). In the 37 men with NOA included in this study, the amount of biopsied tissue was determined at the surgery site and biopsies were taken until it was thought more biopsies would impair the blood supply. The third study evaluated testicular volume in men undergoing conventional TESE (n = 40, including men with NOA, OA and Klinefelter) or microdissection TESE (n = 80, including men with NOA, OA and Klinefelter) (Okada et al., 2002). Measurements of testicular volume were performed at 2 weeks, 1 month and 6 months after TESE but only the data of 6 months after TESE of 120 men were reported. Six months after TESE a decreased testicular volume of at least 2 ml was observed in 25% of the men after conventional TESE and in 2.5% of the men after microdissection TESE. The amount of tissue removed in microdissection TESE was comparable of that of the conventional TESE and ranged between 100 and 300 mg. The fourth study measured the testicular volume on average 18 months after TESE in 39 men (Schill et al., 2003). An increase of 4.3 ml in volume is described. However, the volume was measured in only 26 men before TESE. The fifth study measured the bilateral change in testicular volume 6 weeks after the surgery in 67 men with NOA, OA or Klinefelter (Altinkilic et al., 2017). At this time point, the mean testicular volume was decreased with a difference of 1.5–1.9 ml for, respectively, right or left testis but it is not described if the TESE procedure was performed left, right or bilateral. The volume of the biopsies was not reported. Taken together, although different results were found in each study, three out of five studies show a decrease in testicular volume 6 weeks to 12 months after TESE. The study that did not see any changes was the only study performing TESA (Westlander et al., 2001). Another study that reported an increase in the testicular volume after TESE did not measure the testis volume in all men before TESE. Discussion In this review we evaluated hypogonadism in men with azoospermia after TESE surgery and showed that few high quality data are available from literature. We found there is a temporary decrease in serum total testosterone levels after TESE, for at least 1 year, with levels that may decrease below 12 nmol/l, a threshold level for risk of becoming hypogonadal. The available information on signs and symptoms of hypogonadism after TESE suggests that some men may experience ED, together with depression and anxiety, and a decrease in testicular size. Testosterone as a measure for hypogonadism All included studies presented data on serum total testosterone, one of the measures to determine hypogonadism. The decrease in mean serum total testosterone levels was most profound 6 months after TESE and recovered again to baseline levels after 18 months in men with NOA as well as in men with Klinefelter syndrome. Overall, we saw a greater effect of TESE on mean total testosterone levels in men with Klinefelter syndrome compared to men with NOA. Men with Klinefelter syndrome have decreased basal testosterone levels during and after puberty (Rohayem et al., 2016). Because of their low baseline levels, these men might be more sensitive to a decrease in testosterone levels after TESE. Another explanation is that in men with Klinefelter syndrome the testicular volume is small (Rohayem et al., 2016). Because of this smaller testis the percentage of tissue removed during the TESE biopsy is relatively high compared to men with a bigger testis and subsequently the area of tissue that is damaged will be higher. Interpretation of the consequence of low testosterone levels is not straightforward in view of the different cut-off values suggested by different professional societies and expert groups. According to the Endocrine Society, levels lower than 10.4 nmol/l can be regarded as associated with hypogonadism (Bhasin et al., 2010). On the other hand, the European Association of Urology suggests that levels below 12 nmol/l are associated with symptoms related to hypogonadism (Dohle et al., 2015). At 6 months after TESE, the mean total testosterone levels of men with Klinefelter syndrome were 4.5–6.3 nmol/l and for men with NOA, 8.7–16.4 nmol/l. This implies that in men with Klinefelter and in a proportion of men with NOA total testosterone levels drop below the threshold of 12 nmol/l and thus have a risk of developing symptoms and signs associated with hypogonadism after TESE. We expect the highest prevalence of low total testosterone levels 6 months after TESE, because of the fact that we see the most profound decrease in mean total testosterone levels at this time point. Two out of five studies measured the prevalence at 6 months and these two studies found low testosterone levels in 53 and 5% of the men (Manning et al., 1998; Okada et al., 2002). However, Manning et al. (1998) did not report the threshold used, while Okada et al. (2002) used a very low threshold of 4.9 nmol/l. The other studies that measured prevalence of low testosterone used a follow-up time varying from 1 to 26 months after TESE. Clinical signs and symptoms of hypogonadism Patients will experience hypogonadism by their symptoms rather than on serum testosterone levels. Although cut-off values of serum testosterone levels help to diagnose hypogonadism after TESE, it is not clear whether the TESE-induced decrease in total testosterone levels, irrespective of the levels of serum total testosterone before TESE, might lead to hypogonadism. Therefore, symptoms are more clinically relevant in order to diagnose patients for hypogonadism. New-onset ED was measured in 13 out of 66 men at 6 months after TESE. This was accompanied by a significant decrease in mean total testosterone levels below 12 nmol/l. This suggests that ED after TESE might be explained by hypogonadism, although we cannot exclude that ED is caused by psychological reasons instead of decreased total testosterone levels. ED was especially found in the group of men with unsuccessful sperm retrieval, depression and anxiety, and these factors may have resulted in the ED. However, depression and anxiety can, in addition to causing ED, also be symptoms of hypogonadism. Another possible explanation of the higher prevalence of ED in the group with unsuccessful sperm retrieval is that possibly more biopsies are taken from these men. This might contribute to a higher risk of a decrease in testosterone levels and therefore ED (Manning et al., 1998). An effect of TESE on testicular volume was seen in studies at 6 weeks to 12 months after the procedure, although this effect was less after microdissection TESE. When longer follow-up was reported, no effect was seen of TESE or TESA on testicular volume. This suggests that timing of the follow-up is important. Strengths of this systematic review This review is the first to combine all the reported data on TESE-induced hypogonadism. Because we were able to pool data from these studies, leading to a cohort of 54 men with Klinefelter syndrome and 252 men with NOA, we can conclude that serum total testosterone levels decrease after TESE surgery to levels that might be related to symptoms and signs for hypogonadism. This was supported by the prevalence of new-onset ED and the occurrence of decreased testicular volume after TESE. This information can be taken into account in counselling and follow-up of the men with azoospermia after TESE. Limitations in the interpretation First and foremost, the data are limited by the low number of studies and, in addition, the small size of the available cohorts. Furthermore, most studies only reported on serum total testosterone levels. Strikingly, although TESE is routinely applied, there are only follow-up data available for 54 men with Klinefelter and 252 men with NOA, suitable for our meta-analysis. Because not all studies used the same follow-up time after TESE, these numbers are not representative for all time-points. Furthermore, although more data on total testosterone levels after TESE were available, not all studies reported the data separately for men with different types of azoospermia. Therefore, we could not use all the studies in these analyses. In addition, we had to exclude the largest study because no SDs were described in this study (Ramasamy et al., 2005); however, the results of this study are in line with our results of the meta-analysis.The effect of TESE on decreased total testosterone levels is based on mean total testosterone levels and, because of this, the observed effects may be an underestimation in individuals. A decrease in total testosterone levels in individuals could be missed when looking at the mean levels of a cohort. Therefore, normal mean total testosterone levels do not rule out the presence of men with total testosterone levels below 12 nmol/l that are at risk for symptoms of hypogonadism. Although we were able to do a separate analysis for men with Klinefelter syndrome and men with NOA, we were not able to study the group of men with OA with the available data. It is possible that the risk of hypogonadism differs between various causes of subfertility. In line with this it was shown that the prevalence of low testosterone levels in general in men with NOA is reported to be 45%, while in men with OA this is 16.7% (Sussman et al., 2008). In addition, lower testosterone baseline levels for men with maturation arrest and Sertoli cell only syndrome were found compared to men with hypospermatogenesis (Takada et al., 2008). Therefore, heterogeneity in the mixed population studied might be a potential source of bias. As a results of this possible bias, we tried to separate these data where possible. In addition we were not able to analyse separately the data for various TESE techniques. While in the conventional/open biopsy technique biopsies are taken randomly from different areas of the testis, in the microdissection TESE the location of the biopsies are determined in a more directed way, with the use of a microscope. Therefore, it might be easier to avoid damage caused by destruction of blood vessels and for that reason it is thought microdissection TESE could cause less damage (Shin and Turek, 2013). With TESA and trucut needle testicular biopsy, a needle is used to puncture the tissue, with or without first puncturing the skin with a scalpel, followed by suction of cells and small pieces of tissue. Although the area of damage might be less when using a needle, the location is less well identified. In the three studies comparing the decrease in total testosterone levels after conventional TESE with that after microdissection TESE, the risk was higher or comparable for conventional TESE (Komori et al., 2004; Okada et al., 2002; Ramasamy et al., 2005). Although the TESE technique is reported as conventional or microdissection TESE, the details of the procedure itself will vary at different institutions. These differences in the TESE procedure might increase the heterogeneity of the data between the studies. Biological interpretations of the evidence The effect of TESE on total testosterone can be explained by different mechanisms. The first explanation is that part of the testicular tissue is removed resulting in a lower number of Leydig cells and therefore a lower production of testosterone. However, with decreased serum testosterone levels, the remaining Leydig cells will be stimulated by higher LH levels due to the negative feedback in the hypothalamus–pituitary–gonad axis, and they should become more active in producing testosterone. Nevertheless, it has been shown that stimulation of Leydig cells with hCG after TESE in men with low testosterone levels showed an adequate response, with increased testosterone levels 3 and 4 days after hCG injection. Therefore, these Leydig cells are able to produce more testosterone when they are stimulated, suggesting that in these men a more systemic cause of low LH levels could underlie the hypogonadism after TESE. Indeed, when LH was upregulated immediately after TESE a faster recovery than 18 months was likely expected. Although some studies showed an increase in LH levels after TESE, the normal correlation between LH and total testosterone was not always observed. In one study high LH levels and normal testosterone levels were found in men with NOA and OA (Ishikawa et al., 2009). This combination of high LH and normal testosterone levels is called compensated hypogonadism and might lead to hypogonadism in the future (Tajar et al., 2010). At this point Leydig cells need a higher stimulation to be able to produce normal testosterone levels. However, the number of reports on LH concentrations in relation to testosterone concentrations after TESE is limited and further research would give more insights in the various forms of hypogonadism. A second explanation of the recovery of total testosterone levels is related to the time to repopulate Leydig cells by stem Leydig cells and therefore restore testosterone production at 18 month after TESE. In the rat testis it takes 21 days for new adult Leydig cells to appear from stem Leydig cells after they were chemically destroyed (Jackson et al., 1986). For human Leydig cells, we expect this to be longer than 21 days, however, it is unknown what the exact time span is for human Leydig cells to repopulate the testis. A third and more likely possibility is that the number and function of the Leydig cells is not the cause of decreased total testosterone levels after TESE, but that this is induced by vascular damage in the testis. This vascular damage can result in lower stimulation of Leydig cells by LH because it cannot reach the Leydig cells efficiently, or testosterone is produced in the testis at normal levels but cannot be released into the blood circulation. Indeed, several studies have reported ultrasound findings after TESE and document hypoechoic focal lesions, suggesting haematoma up to 1 and 3 months after TESE, and hyporechoic foci suggestive of scar tissue at 3 and 6 months after TESE (Donoso et al., 2007). Conclusion Although limited studies were obtained from our systematic search, based on the extracted data we found transient but significantly decreased total testosterone levels after TESE that recover to baseline levels after 18–26 months. This effect was most profound in men with Klinefelter syndrome. The number of studies reporting on symptoms and signs of hypogonadism associated with TESE is very limited, showing some risk of ED, which seems to be related to a decreased total testosterone and/or possible depression and anxiety. Furthermore, a decrease in testicular volume is seen in some men after TESE. For better counselling of TESE patients on the transient hypogonadism after TESE, more research is necessary to understand whether the decreased total testosterone is accompanied by symptoms and signs of hypogonadism in the short and long term. It is striking that these data are still not available 25 years after the clinical introduction of TESE. Supplementary data Supplementary data are available at Human Reproduction Update online. Acknowledgements We thank the corresponding authors of included studies who provided additional information on their data upon our request. Authors’ roles J.E. performed the literature search, data extraction and took the lead in writing the manuscript. J.E. and A.v.P. selected the studies. J.E. and M.v.W. performed risk of bias assessment and M.v.W. provided statistical support and performed the meta-regression analysis. All authors took part in the design of the study and writing and revising several drafts of the article. Funding This study was funded by the Academic Medical Center and no external funding was either sought or obtained for this study. Conflict of interest The authors report no financial or other conflict of interest relevant to the subject of this article. References Akbal C , Mangir N , Tavukçu HH , Özgür Ö , Şimşek F . Effect of testicular sperm extraction outcome on sexual function in patients with male factor infertility . Urology 2010 ; 75 : 598 – 601 . Google Scholar CrossRef Search ADS PubMed Altinkilic B , Pilatz A , Diemer T , Wolf J , Bergmann M , Schönbrunn S , Ligges U , Schuppe H-C , Weidner W . Prospective evaluation of scrotal ultrasound and intratesticular perfusion by color-coded duplex sonography (CCDS) in TESE patients with azoospermia . World J Urol 2017 ; 36 : 125 – 133 . Google Scholar CrossRef Search ADS PubMed Bhasin S , Cunningham GR , Hayes FJ , Matsumoto AM , Snyder PJ , Swerdloff RS , Montori VM . Testosterone therapy in adult men with androgen deficiency syndromes: An Endocrine Society Clinical Practice Guideline . J Clin Endocrinol Metab 2010 ; 95 : 2536 – 2559 . http://www.ncbi.nlm.nih.gov/pubmed/20525905%5Cnhttp://press.endocrine.org/doi/full/10.1210/jc.2009-2354. Google Scholar CrossRef Search ADS PubMed Bhasin S , Pencina M , Jasuja GK , Travison TG , Coviello A , Orwoll E , Wang PY , Nielson C , Wu F , Tajar A et al. . Reference ranges for testosterone in men generated using liquid chromatography tandem mass spectrometry in a community-based sample of healthy nonobese young men in the framingham heart study and applied to three geographically distinct cohorts . J Clin Endocrinol Metab 2011 ; 96 : 2430 – 2439 . Google Scholar CrossRef Search ADS PubMed Binsaleh S , Alhajeri D , Madbouly K . Microdissection testicular sperm extraction in men with nonobstructive azoospermia: experience of King Saud University Medical City, Riyadh, Saudi Arabia . Urol Ann 2017 ; 9 : 136 – 140 . Google Scholar CrossRef Search ADS PubMed Bobjer J , Naumovska M , Giwercman YL , Giwercman A . High prevalence of androgen deficiency and abnormal lipid profile in infertile men with non-obstructive azoospermia . Int J Androl 2012 ; 35 : 688 – 694 . Google Scholar CrossRef Search ADS PubMed Bocca S , Moussavi V , Brugh V , Morshedi M , Stadtmauer L , Oehninger S . ICSI outcomes in men undergoing TESE for azoospermia and impact of maternal age . Andrologia 2017 ; 49 . 10.1111/and.12617 . Bourne H , Watkins W , Speirs A , Baker HW . Pregnancies after intracytoplasmic injection of sperm collected by fine needle biopsy of the testis . Fertil Steril 1995 ; 64 : 433 – 436 . http://www.ncbi.nlm.nih.gov/pubmed/7615125. Google Scholar CrossRef Search ADS PubMed Chan PT , Schlegel PN . Nonobstructive azoospermia . Curr Opin Urol 2000 ; 10 : 617 – 624 . Google Scholar CrossRef Search ADS PubMed Cissen M , Meijerink AM , D’Hauwers KW , Meissner A , Van Der Weide N , Mochtar MH , De Melker AA , Ramos L , Repping S , Braat DDM et al. . Prediction model for obtaining spermatozoa with testicular sperm extraction in men with non-obstructive azoospermia . Hum Reprod 2016 ; 31 : 1934 – 1941 . Google Scholar CrossRef Search ADS PubMed Corona G , Pizzocaro A , Lanfranco F , Garolla A , Pelliccione F , Vignozzi L , Ferlin A , Foresta C , Jannini EA , Maggi M et al. . Sperm recovery and ICSI outcomes in Klinefelter syndrome: a systematic review and meta-analysis . Hum Reprod Update 2017 ; 23 : 265 – 275 . Google Scholar CrossRef Search ADS PubMed Craft I , Bennett V , Nicholson N . Fertilising ability of testicular spermatozoa . Lancet 1993 ; 342 : 864 . Google Scholar CrossRef Search ADS PubMed Deruyver Y , Vanderschueren D , Van der Aa F . Outcome of microdissection TESE compared with conventional TESE in non-obstructive azoospermia: a systematic review . Andrology 2014 ; 2 : 20 – 24 . Google Scholar CrossRef Search ADS PubMed Dohle GR , Arver S , Bettocchi C , Jones TH , Kliesch S , Punab M . Male hypogonadism. 2015 . Donoso P , Tournaye H , Devroey P . Which is the best sperm retrieval technique for non-obstructive azoospermia? A systematic review . Hum Reprod Update 2007 ; 13 : 539 – 549 . Google Scholar CrossRef Search ADS PubMed Esteves SC . Serial ultrasonography, hormonal profile and antisperm antibody response after testicular sperm aspiration: editorial comment . Int Braz J Urol 2002 ; 28 : 167 – 168 . Esteves S , Agarwal A . Reproductive outcomes, including neonatal data, following sperm injection in men with obstructive and nonobstructive azoospermia: case series and systematic review . Clinics 2013 ; 68 : 141 – 149 . http://clinics.org.br/article.php?id=1000. Google Scholar CrossRef Search ADS PubMed Everaert K , De Croo I , Kerckhaert W , Dekuyper P , Dhont M , Van der Elst J , De Sutter P , Comhaire F , Mahmoud A , Lumen N . Long term effects of micro-surgical testicular sperm extraction on androgen status in patients with non obstructive azoospermia . BMC Urol 2006 ; 6 : 9 . Google Scholar CrossRef Search ADS PubMed Ishikawa T , Yamaguchi K , Chiba K , Takenaka A , Fujisawa M . Serum Hormones in patients with nonobstructive azoospermia after microdissection testicular sperm extraction . J Urol 2009 ; 182 : 1495 – 1499 . 10.1016/j.juro.2009.06.029 Google Scholar CrossRef Search ADS PubMed Jackson AE , O’Leary PC , Ayers MM , Kretser DM . The effects of ethylene dimethane sulphonate (EDS) on rat Leydig cells: evidence to support a connective tissue origin of Leydig cells . Biol Reprod 1986 ; 35 : 425 – 437 . Google Scholar CrossRef Search ADS PubMed Jungwirth A , Diemer T , Dohle GR , Giwercman A , Kopa Z , Krausz C , Turnaye H . Guidelines on male infertility . Eur Urol 2015 ; 62 : 324 – 332 . Google Scholar CrossRef Search ADS Komori K , Tsujimura A , Miura H , Shin M , Takada T , Honda M , Matsumiya K , Fujioka H . Serial follow-up study of serum testosterone and antisperm antibodies in patients with non-obstructive azoospermia after conventional or microdissection testicular sperm extraction . Int J Androl 2004 ; 27 : 32 – 36 . Google Scholar CrossRef Search ADS PubMed Manning M , Jünemann KP , Alken P . Decrease in testosterone blood concentrations after testicular sperm extraction for intracytoplasmic sperm injection in azoospermic men . Lancet 1998 ; 352 : 37 . Google Scholar CrossRef Search ADS PubMed Meijerink AM , Cissen M , Mochtar MH , Fleischer K , Thoonen I , De Melker AA , Meissner A , Repping S , Braat DDM , VanWely M et al. . Prediction model for live birth in ICSI using testicular extracted sperm . Hum Reprod 2016 ; 31 : 1942 – 1951 . Google Scholar CrossRef Search ADS PubMed Okada H , Dobashi M , Yamazaki T , Hara I , Fujisawa M , Arakawa S , Kamidono S . Conventional versus microdissection testicular sperm extraction for nonobstructive azoospermia . J Urol 2002 ; 168 : 1063 – 1067 . Google Scholar CrossRef Search ADS PubMed Ozturk U , Ozdemir E , Dede O , Sagnak L , Goktug HNG , Gurbuz OA , Cagatay M , Imamoglu MA . Assessment of anti-sperm antibodies in couples after testicular sperm extraction . Clin Investig Med 2011 ; 34 : 179 – 184 . Google Scholar CrossRef Search ADS Ramasamy R , Yagan N , Schlegel PN . Structural and functional changes to the testis after conventional versus microdissection testicular sperm extraction . Urology 2005 ; 65 : 1190 – 1194 . Google Scholar CrossRef Search ADS PubMed Rohayem J , Nieschlag E , Zitzmann M , Kliesch S . Testicular function during puberty and young adulthood in patients with Klinefelter’s syndrome with and without spermatozoa in seminal fluid . Andrology 2016 ; 4 : 1178 – 1186 . Google Scholar CrossRef Search ADS PubMed Schill T , Bals-Pratsch M , Küpker W , Sandmann J , Johannisson R , Diedrich K . Clinical and endocrine follow-up of patients after testicular sperm extraction . Fertil Steril 2003 ; 79 : 281 – 286 . Google Scholar CrossRef Search ADS PubMed Schlegel PN , Li PS . Microdissection TESE: sperm retrieval in non-obstructive azoospermia . Hum Reprod Updat 1998 ; 4 : 439 . http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9825858. Google Scholar CrossRef Search ADS Schlegel PN , Su LM . Physiological consequences of testicular sperm extraction . Hum Reprod 1997 ; 12 : 1688 – 1692 . Google Scholar CrossRef Search ADS PubMed Schoysman R , Vanderzwalmen P , Nijs M , Segal L , Segal-Bertin G , Geerts L , van Roosendaal E , Schoysman D . Pregnancy after fertilisation with human testicular spermatozoa . Lancet 1993 ; 342 : 1237 . Google Scholar CrossRef Search ADS PubMed Shin DH , Turek PJ . Sperm retrieval techniques . Nat Rev Urol 2013 ; 10 : 723 – 730 . Google Scholar CrossRef Search ADS PubMed Steele EK , Ellis PK , Lewis SEM , McClure N . Ultrasound, antisperm antibody, and hormone profiles after testicular Trucut biopsy . Fertil Steril 2001 ; 75 : 423 – 428 . Google Scholar CrossRef Search ADS PubMed Sterne JA , Hernán MA , Reeves BC , Savović J , Berkman ND , Viswanathan M , Henry D , Altman DG , Ansari MT , Boutron I et al. . ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions . Br Med J 2016 ; 355 : i4919 . Google Scholar CrossRef Search ADS Sussman EM , Chudnovsky A , Niederberger CS . Hormonal evaluation of the infertile male: has it evolved? Urol Clin North Am 2008 ; 35 : 147 – 155 . Google Scholar CrossRef Search ADS PubMed Tajar A , Forti G , O’Neill TW , Lee DM , Silman AJ , Finn JD , Bartfai G , Boonen S , Casanueva FF , Giwercman A et al. . Characteristics of secondary, primary, and compensated hypogonadism in aging men: evidence from the European male ageing study . J Clin Endocrinol Metab 2010 ; 95 : 1810 – 1818 . Google Scholar CrossRef Search ADS PubMed Takada S , Tsujimura A , Ueda T , Matsuoka Y , Takao T , Miyagawa Y , Koga M , Takeyama M , Okamoto Y , Matsumiya K et al. . Androgen decline in patients with nonobstructive azoospemia after microdissection testicular sperm extraction . Urology 2008 ; 72 : 114 – 118 . Google Scholar CrossRef Search ADS PubMed The Prisma Group from Moher D, Liberati A, Tetzlaff J, AD . Preferred reporting items for systematic reviews and meta analyses: The Prisma Statement . PLoS Med 2009 ; 6 : 1 – 15 . www.prisma-ststement.org. CrossRef Search ADS Van Peperstraten A , Proctor ML , Johnson NP , Philipson G . Techniques for surgical retrieval of sperm prior to intra-cytoplasmic sperm injection (ICSI) for azoospermia . Cochrane Database Syst Rev 2008 ; CD002807 . Van Wely M , Barbey N , Meissner A , Repping S , Silber SJ . Live birth rates after MESA or TESE in men with obstructive azoospermia: is there a difference? Hum Reprod 2015 ; 30 : 761 – 766 . Google Scholar CrossRef Search ADS PubMed Wang C , Nieschlag E , Swerdloff R , Behre HM , Hellstrom WJ , Gooren LJ , Kaufman JM , Legros JJ , Lunenfeld B , Morales A et al. . Investigation, treatment, and monitoring of late-onset hypogonadism in males: ISA, ISSAM, EAU, EAA, and ASA Recommendations . Eur Urol 2009 ; 55 : 121 – 130 . Google Scholar CrossRef Search ADS PubMed Westlander G , Ekerhovd E , Granberg S , Lycke N , Nilsson L , Werner C , Bergh C . Serial ultrasonography, hormonal profile and antisperm antibody response after testicular sperm aspiration . Hum Reprod 2001 ; 16 : 2621 – 2627 . Google Scholar CrossRef Search ADS PubMed Zitzmann M , Faber S , Nieschlag E . Association of specific symptoms and metabolic risks with serum testosterone in older men . J Clin Endocrinol Metab 2006 ; 91 : 4335 – 4343 . Google Scholar CrossRef Search ADS PubMed © The Author(s) 2018. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

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Human Reproduction UpdateOxford University Press

Published: May 3, 2018

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