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Does This Patient Have Deep Vein Thrombosis?

Does This Patient Have Deep Vein Thrombosis? Abstract Objective.— To review the validity of the clinical assessment and diagnostic tests in patients with suspected deep vein thrombosis (DVT). Methods.— A comprehensive review of the literature was conducted by searching MEDLINE from 1966 to April 1997. Results.— Individual symptoms and signs alone do not reliably predict which patients have DVT. Overall, the diagnostic properties of the clinical examination are poor; the sensitivity of the clinical examination ranges from 60% to 96%, and the specificity ranges from 20% to 72%. However, using specific combinations of risk factors, symptoms, and physical signs for DVT, clinicians can reliably stratify patients with suspected DVT into low, moderate, or high pretest probability categories of actually suffering from DVT. This stratification process in combination with noninvasive testing, such as compression ultrasonography, simplifies the management strategies for patients with suspected DVT. Conclusions.— Use of a clinical prediction guide that includes specific factors from both the history and physical examination in combination with noninvasive tests simplifies management strategies for patients with suspected DVT. DEEP VEIN thrombosis (DVT) affects approximately 2 million Americans per year1 and is the third most common cardiovascular disease behind acute coronary syndromes and stroke.2 Venous thromboembolism represents a single disease entity with 2 patterns of clinical presentation: DVT and pulmonary embolism (PE). The approach to patients who present with suspected DVT is problematic for several reasons. If left untreated, affected patients can suffer fatal PE. The clinical diagnosis of DVT is unreliable when used in isolation without objective testing.3,4 Also, about three quarters of the patients who present with suspected DVT have nonthrombotic causes of leg pain.5,6 Finally, although anticoagulant therapy is highly effective in preventing the extension, embolization, and recurrence of DVT, it is associated with an increased risk of major bleeding (approximately 5%) and other potentially serious consequences such as heparin-induced thrombocytopenia (approximately 1%).7 Therefore, when possible, anticoagulation should be restricted to those with confirmed DVT. For all of these reasons, it is important to diagnose DVT accurately. This will allow administration of appropriate therapy for patients with documented DVT, and for patients without DVT it will avoid unnecessary exposure of patients to the hazards of anticoagulant therapy, and prevent many from being falsely labeled as suffering from venous thromboembolic disease. The low specificity of clinical symptoms and signs means that most symptomatic patients will not have DVT. Of those symptomatic patients with confirmed DVT at presentation, which represents about one quarter of patients who are investigated,6,8 approximately 80% have proximal DVT (popliteal or more proximal veins) and 20% have DVT that is limited to the calf.9 The clinical significance of proximal DVT is different from that of calf vein thrombosis because proximal vein thrombosis is associated with a higher incidence of PE. Pulmonary emboli are detected in approximately 50% of patients with documented proximal DVT.10 Therefore, proximal DVT should be identified and anticoagulant treatment should be initiated immediately in affected patients. The initiation of appropriate treatment reduces the risk of developing recurrent DVT to about 5% and reduces the incidence of fatal PE to less than 1%.1,11 On the other hand, calf vein thrombosis rarely causes PE unless it first extends into the proximal veins. Proximal extension of calf DVT occurs in approximately 30%, with propagation occurring within 1 to 2 weeks of initial presentation.6 Clinical scenario A 55-year-old woman is referred to you with suspected DVT. She complains of pain, swelling, warmth, and redness of her right calf. She denies injury to the leg, or previous DVT. She has been receiving intravenous combination chemotherapy for ovarian carcinoma that was diagnosed 6 months earlier. Extensive pelvic lymph node involvement, especially on the right side, was present at diagnosis, and you consider the possibility that her leg symptoms are due to extrinsic compression of the right iliac vein. However, no lymph nodes are palpable and a recent pelvic ultrasound examination showed a reduction in the previously demonstrated adenopathy. On physical examination you find pitting edema, erythema, increased warmth of the right calf (diameter 3.5 cm greater than that of the left calf), and tenderness with palpation of the popliteal vein. You apply a clinical prediction rule6 and conclude that the probability of proximal DVT is very high. Methods Search Strategy We conducted a MEDLINE search to retrieve all relevant articles pertaining to the clinical assessment of patients with suspected DVT. MEDLINE was searched from 1966 to April 1997 using Medical Subject Headings, EXP (explode) thrombosis (tw [textword]) and (EXP physical examination or EXP diagnostic tests or EXP sensitivity and specificity) and EXP phlebography. This was limited to human and English-language studies. One hundred fifteen articles were retrieved (available on request from the senior author); 68 articles that dealt with the diagnosis of DVT were selected for complete review. The bibliographies of the retrieved articles were examined for additional relevant articles. Only 5 studies provided information on the relationship between clinical findings and venographic confirmation of DVT.3,4,6,12,13 These studies were graded based on their methodologic quality using a standard scoring system.14 Principles of Diagnosis of DVT The diagnostic assessment of patients with suspected DVT has evolved over the past 2 decades from reliance on clinical symptoms and signs alone to heavy reliance on objective diagnostic tests.15 Results Clinical Assessment Over the past 30 years, the clinical assessment in patients with suspected DVT has been refined and now includes a careful review of risk factors, symptoms, and physical signs.5,16-18 Risk factors for DVT include immobility, paralysis, recent surgery and/or trauma, malignancy, cancer chemotherapy, advancing age (ie, >60 years), family history of venous thromboembolism, pregnancy, and estrogen use.19,20 In a recent prospective cohort study, 426 consecutive outpatients referred by general practitioners to a tertiary care thrombosis unit were assessed for DVT risk factors, and in approximately half of the patients with confirmed DVT, a major risk factor (immobility, trauma, and/or recent surgery) was present.19 The odds ratios for other risk factors independently associated with the presence of DVT, including male gender, age greater than 60 years, cancer, heart failure, systemic lupus erythematosus, and lower limb arteriopathy, are presented in Table 1. Commonly reported symptoms in patients with suspected DVT include leg pain, swelling, and other signs, such as pitting edema, warmth, dilated superficial veins, and erythema.3-5 Unfortunately, these findings are neither sensitive nor specific for DVT and may be caused by other disease processes,5,16 such as leg trauma, cellulitis, obstructive lymphadenopathy, superficial venous thrombosis, postphlebitic syndrome, or Baker cysts.6,21 The odds ratios for these factors range from 1.6 to 4.3.19 Furthermore, DVT can coexist with each of these processes. For example, the finding of a Baker cyst on an ultrasound examination does not rule out the presence of DVT.21 Traditionally, the routine physical examination in patients with suspected DVT included a careful inspection of the leg, measurement of the leg circumference, and elicitation of Homans sign,22 which refers to the development of pain in the calf or popliteal region on forceful and abrupt dorsiflexion of the ankle with the knee in a flexed position. Early studies evaluating the properties of individual physical signs such as these to diagnose DVT showed that they were inaccurate.3,4 In a study by O'Donnell et al,3 102 patients who presented to the outpatient departments of 2 tertiary care hospitals with suspected DVT underwent a clinical assessment and venography. A combination of clinical signs and symptoms that included tenderness, swelling, redness, and the assessment of Homans sign could not adequately differentiate patients with or without DVT. The sensitivity of the clinical examination in this study was 88% (95% confidence interval [CI], 77%-97%) and the specificity was only 30% (95% CI, 18%-40%). Haeger4 conducted a prospective study of 72 outpatients who presented with suspected DVT to a thrombosis clinic, were examined by 1 or 2 experienced surgeons, and underwent venography. No differences in the presenting symptoms or physical signs were identified between those with or without venographically confirmed DVT. The sensitivity of the clinical examination in this study was 66% (95% CI, 50%-82%) and the specificity only 53% (95% CI, 38%-69%). In a study by Molloy et al,12 100 patients with a clinical diagnosis of DVT who were referred to the radiology department of a general hospital were studied; the sensitivity of the clinical examination was 60% (95% CI, 45%-75%) and the specificity was 72% (95% CI, 60%-83%). Overall, these symptoms and signs occur in similar frequency in symptomatic patients with and without DVT (Table 2). The results of these studies led to a shift away from the clinical examination to a heavy reliance on noninvasive objective tests for patients with suspected DVT. More recently, in a retrospective chart review by Landefeld et al13 of 354 inpatients and outpatients with suspected DVT who underwent venography, there were 5 clinical findings independently related to the presence of proximal DVT: swelling below the knee, swelling above the knee, recent immobility, cancer, and fever. These factors were determined by using multiple linear regression, were found to be significantly associated with the presence of proximal DVT in 236 patients, and then were confirmed in the remaining 119 patients. Overall, the sensitivity of a positive clinical examination (associated with the presence of 1 or more independent predictors) was 96% (95% CI, 92%-100%) and the specificity was 20% (95% CI, 15%-25%). The frequency of signs and symptoms seemed to predict the presence of proximal DVT; where the absence of any findings was associated with less than a 5% chance of proximal DVT, and the presence of 2 or more clinical findings was associated with a 46% chance of proximal DVT. This was the first study to demonstrate the potential role of a clinical prediction guide in patients with suspected DVT. The likelihood ratio estimates for the clinical assessment based on the 4 studies described above are shown in Table 3. Recall that a likelihood ratio expresses the odds that a given finding on the history or physical examination would occur in a patient with the target disorder as opposed to a patient without it. Given a likelihood ratio above 1.0, the probability of disease (in this case DVT) increases when the finding is present, as the finding is more likely among the patients with the disease than among those without. When the likelihood ratio is below 1.0, the probability of disease declines as the finding is less likely to occur among patients with the disease than those without.23 Objective Assessment Venography is the reference standard for the diagnosis of DVT, and it is highly accurate for both proximal and calf DVT.24 However, venography is invasive, expensive, technically inadequate in about 10% of patients (either because of an inability to cannulate a vein or lack of adequate visualization of the deep veins), and may induce DVT in approximately 3% of patients.25 This led to the evaluation and validation of 2 noninvasive tests: impedance plethysmography and compression ultrasonography. These tests have proven to be sensitive to proximal, but not to calf vein thrombosis. Impedance plethysmography reliably detects occlusive thrombi of the proximal veins (popliteal, femoral, or iliac veins) but is less reliable at detecting nonocclusive proximal DVT, and is insensitive to calf DVT.26-29 Impedance plethysmography does not allow direct visualization of the veins, but suggests that DVT is present when significant outflow obstruction is present, particularly in the absence of a comorbid condition that might cause a false-positive result (ie, extrinsic venous compression or conditions associated with elevated central venous pressure).15 Although studies before 1990 reported that impedance plethysmography detected over 90% of proximal DVT, more recent studies reported sensitivities for proximal DVT of about 70%.30-32 This apparent decrease in sensitivity is probably caused by changes in referring patterns to speciality centers with a strong interest in DVT.33 Compression ultrasonography assesses compressibility of the femoral and popliteal veins and is highly sensitive and specific for detecting proximal DVT (noncompressibility is diagnostic of DVT, whereas compressibility excludes DVT).6,15,34-36 Neither impedance plethysmography nor compression ultrasonography reliably detects isolated calf vein thrombosis.37 It should be noted that while the specificity of compression ultrasonograpy and impedance plethysmography for DVT remains high in both symptomatic and asymptomatic patients, the sensitivity declines dramatically when impedance plethysmography and compression ultrasonography are used to evaluate asymptomatic patients (ie, 22% and 58%, respectively) vs symptomatic patients (ie, 96 % and 96%, respectively).38 Several diagnostic algorithms using serial compression ultrasonography or impedance plethysmography have been evaluated and validated in large clinical trials.26,29,34-36,39-44 Although compression ultrasonography appears to be more accurate than impedance plethysmography, serial testing with either is acceptable in patients with suspected DVT.39,45 Therefore, as most clinicians consider clinically important proximal DVT excluded by normal impedance plethysmography or compression ultrasonography on the day of presentation, anticoagulants can be safely withheld in such patients, as the probability of suffering from proximal DVT is less than 2% in the following 3 months.46 If the initial test results are normal, repeat testing over the next 5 to 7 days is recommended; if they become abnormal during this period, extending proximal DVT is likely and an anticoagulant therapy should be initiated. However, impedance plethysmography and compression ultrasonography have limitations too, such as availability, and the inconvenience and expense of repeat testing. Recently the D-dimer assays have been demonstrated to be useful adjuncts to noninvasive testing for suspected DVT because they are highly sensitive and, therefore, have high negative predictive values.47-49 D dimer is formed when crossed-linked fibrin contained within a thrombus is proteolyzed by plasmin. Various D-dimer assays are available, including enzyme-linked immunosorbent assays, latex agglutination assays, and a whole blood agglutination test.48 The whole-blood agglutination assay appears to be best for exclusion of DVT, since it is suitable for individual testing (unlike enzyme-linked immunosorbent assays), and has high sensitivity and reasonable specificity. Recent studies show that DVT can be reliably excluded in patients with suspected DVT who have a normal impedance plethysmograph and a normal D dimer (using the SimpliRed assay) and that such results occur in about two thirds of patients.47 This supports the role of the SimpliRed assay as a simple and rapid adjunct to noninvasive tests for the exclusion of clinically important DVT.47,48 For a summary of diagnostic algorithms for patients with suspected DVT see Table 4. Clinical Prediction Guide Recently, the clinical assessment of patients with suspected DVT was reevaluated. This was sparked by 2 observations that many patients with a high pretest probability (using clinical judgment) and a normal impedance plethysmograph had proximal DVT,30 and that the pretest probability of patients had an important influence on diagnosing PE, a closely related disease. For example, in patients with a low pretest probability and a high probability lung scan, the prevalence of PE was approximately 50% to 60%.50 These results generated the hypothesis that when pretest probability and further tests are concordant, DVT can be ruled in or out, whereas when they are discordant, further tests are necessary. Development of a Clinical Prediction Guide Recently, a clinical prediction guide that seeks to standardize the estimation of the pretest probability among clinicians was developed6 and is described below. This model enables clinicians to reliably stratify patients with suspected DVT into high, moderate, or low probability groups by following uniform criteria. After a review of the literature3,4,8,15,19 and input from experienced thrombosis investigators, categories deemed to be important in the estimation of a patient's pretest probability were considered and categorized as follows: (1) signs and symptoms of DVT, (2) risk factors for DVT, and (3) the presence or absence of diagnoses that were deemed at least as likely as DVT to explain the patient's symptoms. These include musculoskeletal injuries, cellulitis, and prominent lymphadenopathy of the inguinal area. The clinical prediction guide uses a scoring system that combines important symptoms and signs, risk factors for DVT, and the presence or absence of an alternative diagnosis. The results stratify patients with suspected DVT into low, moderate, or high probability groups. The original clinical prediction guide was initially developed in a training set of 100 outpatients at a thrombosis referral center, at McMaster University, Hamilton, Ontario, who presented with suspected DVT. All patients underwent venography, and a simple regression model determined the relative importance of individual and various clusters of factors to predict the probability that a patient suffered from DVT. The clinical prediction guide was then prospectively validated in a test set of 529 patients who presented with suspected DVT to 3 tertiary care referral centers, 2 in Hamilton and 1 in Padua, Italy.6 Clinicians recorded their assessment of pretest probability of DVT, then all patients underwent venography and compression ultrasound examination. This model cannot be applied to certain subgroups of patients who were excluded from the study, such as those with previous venous thromboembolism, those with concomitantly suspected PE, pregnant women, or patients receiving treatment with anticoagulants. Using the clinical model, eligible patients were initially stratified into low, moderate, or high pretest probability groups. Although individual physical findings on their own are not predictive of DVT, when specific physical signs are incorporated into the clinical prediction guide they contribute to the generation of the pretest probability of DVT. In Table 5, the physical signs and the scoring system of the clinical prediction guide are outlined. The physical signs classified as major points include localized tenderness to palpation along the distribution of the deep venous system; thigh and calf swelling—indicating that the entire leg has an increased diameter when compared with the asymptomatic side; and calf swelling in which the calf is measured approximately 10 cm below the tibial plateau (at the tibial tuberosity) and is considered present if the difference between calf diameters is greater than 3 cm. Minor points include the presence of a unilateral pitting edema of the leg using standard assessment measures; the presence of dilated superficial veins (nonvaricose) that persist with elevation in the lower limb or if present in any new pattern in the groin region on the symptomatic leg only; and the presence of diffuse or streaking erythema. The test-set confirmed that the clinical model could reliably classify patients into high, moderate, and low probability groups. The prevalence of all DVT (proximal and calf) using the venogram as the criterion standard in patients who were classified by the clinical model into the high probability strata was 85%, compared with 33% in the moderate probability and 5% in the low probability categories. The positive likelihood ratios for the high-, moderate-, and low-risk categories are 3.3 (95% CI, 2.6-4.3), 1.3 (95% CI, 1.0-1.7), and 0.2 (95% CI, 0.1-0.3), respectively. The specificity of compression ultrasonography to detect proximal DVT in all strata was between 98% and 100%. When interpreted in conjunction with pretest probability, the ability of compression ultrasonography to reliably diagnose DVT decreased as the pretest probability declined. The sensitivities of compression ultrasonography in the high, moderate, and low strata were 94%, 83%, and 80%, respectively. The corresponding likelihood ratios for compression ultrasonography in pretest probability strata are provided in Table 6. By combining pretest probability and compression ultrasonography results, the posttest probabilities of DVT for each possible combination of results were generated. In the high pretest probability strata, an abnormal compression ultrasonogram resulted in a 100% posttest probability; in the moderate strata, a 96% posttest probability; and in the low strata, a 63% posttest probability. In patients whose compression ultrasonogram was normal, the posttest probabilities of DVT in the high, moderate, and low strata were 24%, 5%, and less than 1%, respectively. The original clinical prediction guide was recently simplified using stepwise logistic regression and reevaluated.51 Recent trauma, family history, erythema, and recent hospitalization within the previous 6 months did not remain in the simplified model, which in combination with compression ultrasonography was recently prospectively tested in 593 patients with suspected DVT who were referred to tertiary care thrombosis clinics51 (Table 7). Similar to the original clinical prediction guide, the simplified guide was able to reliably stratify patients into high, moderate, or low probability groups, with corresponding prevalences of DVT of 75% (95% CI, 63%-81%), 17% (95% CI, 12%-23%), and 3% (95% CI, 1.7%-5.9%), respectively. These data support the use of a clinical prediction guide to simplify the diagnostic approach for patients with suspected DVT (Figure 1). In patients with a high or moderate pretest score who have an abnormal compression ultrasonogram, DVT can be reliably diagnosed (positive likelihood ratios of ∞ and 72, respectively) and treatment should be initiated. In patients with a low pretest probability of DVT who have a normal compression ultrasonogram (negative likelihood ratio of 0.2), DVT can be reliably excluded without further testing. For patients with discordant results (ie, high pretest probability and normal compression ultrasonogram, or low pretest probability and an abnormal compression ultrasonorgram), further testing is recommended (ie, venography or serial compression ultrasonography). Patients with a moderate pretest probability and a normal ultrasonogram have a 5% probability of having DVT and a repeat compression ultrasound examination in 7 days is recommended. Back to the patient The patient described in the "Clinical Scenario" section is a 55-year-old woman who presents with suspected DVT. Using the clinical prediction guide checklist found in Table 5, you determine that she has 5 clinical features predictive of DVT: a diagnosis of active cancer, calf swelling, erythema, localized tenderness along the popliteal vein, and pitting edema of the symptomatic leg. Although the possibility of enlarging pelvic lymph nodes in the right inguinal area offers a potential alternative diagnosis, you note that a recent pelvic ultrasound report indicates that these nodes have shrunk, rendering this a less likely alternative diagnosis. Therefore, with 5 clinical features of DVT, and no convincing alternative diagnosis, following the approach of the clinical prediction guide you conclude that she has a high clinical probability of suffering from acute DVT. The next step is to perform a compression ultrasound examination, and, if the results are abnormal, the posttest probability of DVT being present approaches 100%. However, if the ultrasonogram is normal (ie, showing normal compressibility of the proximal veins), the posttest probability is approximately 24%, and further testing with venography would be required. Conclusions Although physical findings of patients with suspected DVT are not useful on their own, this state-of-the-art clinical prediction guide that includes factors from both the history and physical examination is able to assist in the diagnosis of DVT. When used in combination with noninvasive tests, such as compression ultrasonography, it can simplify and reduce the expense of management strategies. The bottom line Individual symptoms and signs on their own are not useful to diagnose DVT. However, a systematic review of patients' risk factors, symptoms, and physical signs allows the clinician to reliably determine the pretest probability that a patient suffers from DVT. This strategy, in combination with the results of noninvasive diagnostic test results, guides further diagnostic testing and treatment strategies. References 1. Hirsh J, Hoak J. Management of deep vein thrombosis and pulmonary embolism. Circulation.1996;93:2212-2245.Google Scholar 2. Gunintini C, Di Ricco G, Marini C, Melillo E, Palla A. Epidemiology. Chest.1995;107:3S-9S.Google Scholar 3. O'Donnell T, Abbott W, Athanasoulis C, Millan V, Callow A. Diagnosis of deep venous thrombosis in the outpatient by venography. Surg Gynecol Obstet.1980;150:69-74.Google Scholar 4. Haeger K. Problems of acute deep venous thrombosis, I: the interpretation of signs and symptoms. Angiology.1969;20:219-223.Google Scholar 5. Hull RD, Raskob GE, Leclerc J, Jay RM, Hirsh J. 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Philadelphia, Pa: JB Lippincott; 1994:1297-1321. 16. Hirsh J, Hull RD, Raskob GE. Clinical features and diagnosis of venous thrombosis. J Am Coll Cardiol.1986;8(suppl B):114B-127B.Google Scholar 17. Browse N. Deep vein thrombosis: diagnosis. BMJ.1969;684:676-678.Google Scholar 18. McLachlin J, Richard T, Paterson JC. An evaluation of clinical signs in the diagnosis of venous thrombosis. Arch Surg.1962;85:738.Google Scholar 19. Cogo A, Bernardi E, Prandoni P, Girolami B, Noventa F, Simioni P. Acquired risk factors for deep-vein thrombosis in symptomatic outpatients. Arch Intern Med.1994;154:164-168.Google Scholar 20. Salzman EW, Hirsh J. The epidemiology, pathogenesis, and natural history of venous thrombosis. In: Colman RW, Hirsh J, Marder VJ, Salzman EW, eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. Philadelphia, Pa: JB Lippincott; 1994:1275-1296. 21. Simpson PG, Bark M, Robinson PJ, Losowsky MS. Prospective study of thrombophlebitis and pseudothrombophlebitis. Lancet.1980;1:331-333.Google Scholar 22. Barnes RW, Wu KK, Hoak JC. Fallibility of the clinical diagnosis of venous thrombosis. JAMA.1975;234:605-607.Google Scholar 23. Sackett DL. A primer on the precision and accuracy of the clinical examination [abstract]. JAMA.1992;267:2638-2644.Google Scholar 24. Rabinov K, Paulin S. Roentegen diagnosis of venous thrombosis in the leg. Arch Surg.1972;104:134.Google Scholar 25. Lensing AWA, Prandoni P, Buller H, Casara D, Cogo A, ten Cate JW. Lower extremity venography with iohexol: results and complications. Radiology.1990;177:503-505.Google Scholar 26. Hull RD, Hirsh J, Carter CJ. Diagnostic efficacy of impedance plethysmography for clinically-suspected deep-vein thrombosis. Ann Intern Med.1985;102:21-28.Google Scholar 27. Prandoni P, Lensing AWA, Huisman MV. et al. A new computerized impedance plethysmograph: accuracy in the detection of proximal deep-vein thrombosis in symptomatic outpatients. Thromb Hemost.1991;65:229-232.Google Scholar 28. Hull RD, van Acken WG, Hirsh J. et al. Impedance plethysmography using the occlusive cuff technique in the diagnosis of venous thrombosis. Circulation.1976;53:696.Google Scholar 29. Huisman MV, Buller HR, ten Cate JW, Heijermans HSF, van der Laan J, van Maanen DJ. Management of clinically suspected acute venous thrombosis in outpatients with serial impedance plethysmography in a community hospital setting. Arch Intern Med.1989;149:511-513.Google Scholar 30. Anderson DR, Lensing AW, Wells PS, Levine MN, Weitz JI, Hirsh J. Limitations of impedance plethysmography in the diagnosis of clinically suspected deep-vein thrombosis. Ann Intern Med.1993;118:25-30.Google Scholar 31. Prandoni P, Lensing AWA, Buller HR. et al. Failure of computerized impedance plethysmography in the diagnostic management of patients with clinically suspected DVT. Thromb Hemost.1991;65:233.Google Scholar 32. Ginsberg JS, Wells PS, Hirsh J. et al. Reevaluation of the sensitivity of impedance plethysmography for the detection of proximal deep vein thrombosis. Arch Intern Med.1994;154:1930-1933.Google Scholar 33. Cogo A, Prandoni P, Villalta S, Polistena D, Bernardi E, Simioni P. Changing features of proximal vein thrombosis over time. Angiology.1994;45:377-382.Google Scholar 34. Heijboer H, Cogo A, Buller HR, Prandoni P, ten Cate JW. Detection of deep vein thrombosis with impedance plethysmography and real time compression ultrasonography in hospitalized patients. Arch Intern Med.1992;152:1901-1903.Google Scholar 35. White RH, McGahan JP, Daschbach MM, Hartling RP. Diagnosis of deep-vein thrombosis using duplex ultrasound. Ann Intern Med.1989;111:297-304.Google Scholar 36. 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Combined use of leg scanning and impedance plethysmography in suspected venous thrombosis: an alternative to venography. N Engl J Med.1977;296:1497-1500.Google Scholar 41. Huisman MV, Buller HR, ten Cate JW, Vreeken J. Serial impedance plethysmography for suspected deep venous thrombosis in outpatients: the Amsterdam General Practioner Study. N Engl J Med.1986;314:823-828.Google Scholar 42. Cogo A, Lensing AWA, Koopman MMW. Compression ultrasound for the diagnostic management of clinically suspected deep-vein thrombosis. Thromb Hemost.1995;73:1098.Google Scholar 43. Hull R, Hirsh J, Sackett DL. Replacement of venography in suspected venous thrombosis by impedance plethysmography and 125I-fibrinogen leg scanning. Ann Intern Med.1981;94:12-15.Google Scholar 44. Cogo A, Lensing AWA, Prandoni P, Buller HR, Girolami A, ten Cate JW. Comparison of real-time B-mode ultrasonography and Doppler ultrasound with contrast venography in the diagnosis of venous thrombosis in symptomatic outpatients. 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The PIOPED Investigators. The value of the ventilation/perfusion scan in acute pulmonary embolism. JAMA.1990;263:2753-2759.Google Scholar 51. Wells P, Anderson DR, Bormanis J. et al. Value of assessment of pretest probability of deep-vein thrombosis in clinical management. Lancet.1997;350:1795-1798.Google Scholar http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA American Medical Association

Does This Patient Have Deep Vein Thrombosis?

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American Medical Association
Copyright
Copyright © 1998 American Medical Association. All Rights Reserved.
ISSN
0098-7484
eISSN
1538-3598
DOI
10.1001/jama.279.14.1094
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Abstract

Abstract Objective.— To review the validity of the clinical assessment and diagnostic tests in patients with suspected deep vein thrombosis (DVT). Methods.— A comprehensive review of the literature was conducted by searching MEDLINE from 1966 to April 1997. Results.— Individual symptoms and signs alone do not reliably predict which patients have DVT. Overall, the diagnostic properties of the clinical examination are poor; the sensitivity of the clinical examination ranges from 60% to 96%, and the specificity ranges from 20% to 72%. However, using specific combinations of risk factors, symptoms, and physical signs for DVT, clinicians can reliably stratify patients with suspected DVT into low, moderate, or high pretest probability categories of actually suffering from DVT. This stratification process in combination with noninvasive testing, such as compression ultrasonography, simplifies the management strategies for patients with suspected DVT. Conclusions.— Use of a clinical prediction guide that includes specific factors from both the history and physical examination in combination with noninvasive tests simplifies management strategies for patients with suspected DVT. DEEP VEIN thrombosis (DVT) affects approximately 2 million Americans per year1 and is the third most common cardiovascular disease behind acute coronary syndromes and stroke.2 Venous thromboembolism represents a single disease entity with 2 patterns of clinical presentation: DVT and pulmonary embolism (PE). The approach to patients who present with suspected DVT is problematic for several reasons. If left untreated, affected patients can suffer fatal PE. The clinical diagnosis of DVT is unreliable when used in isolation without objective testing.3,4 Also, about three quarters of the patients who present with suspected DVT have nonthrombotic causes of leg pain.5,6 Finally, although anticoagulant therapy is highly effective in preventing the extension, embolization, and recurrence of DVT, it is associated with an increased risk of major bleeding (approximately 5%) and other potentially serious consequences such as heparin-induced thrombocytopenia (approximately 1%).7 Therefore, when possible, anticoagulation should be restricted to those with confirmed DVT. For all of these reasons, it is important to diagnose DVT accurately. This will allow administration of appropriate therapy for patients with documented DVT, and for patients without DVT it will avoid unnecessary exposure of patients to the hazards of anticoagulant therapy, and prevent many from being falsely labeled as suffering from venous thromboembolic disease. The low specificity of clinical symptoms and signs means that most symptomatic patients will not have DVT. Of those symptomatic patients with confirmed DVT at presentation, which represents about one quarter of patients who are investigated,6,8 approximately 80% have proximal DVT (popliteal or more proximal veins) and 20% have DVT that is limited to the calf.9 The clinical significance of proximal DVT is different from that of calf vein thrombosis because proximal vein thrombosis is associated with a higher incidence of PE. Pulmonary emboli are detected in approximately 50% of patients with documented proximal DVT.10 Therefore, proximal DVT should be identified and anticoagulant treatment should be initiated immediately in affected patients. The initiation of appropriate treatment reduces the risk of developing recurrent DVT to about 5% and reduces the incidence of fatal PE to less than 1%.1,11 On the other hand, calf vein thrombosis rarely causes PE unless it first extends into the proximal veins. Proximal extension of calf DVT occurs in approximately 30%, with propagation occurring within 1 to 2 weeks of initial presentation.6 Clinical scenario A 55-year-old woman is referred to you with suspected DVT. She complains of pain, swelling, warmth, and redness of her right calf. She denies injury to the leg, or previous DVT. She has been receiving intravenous combination chemotherapy for ovarian carcinoma that was diagnosed 6 months earlier. Extensive pelvic lymph node involvement, especially on the right side, was present at diagnosis, and you consider the possibility that her leg symptoms are due to extrinsic compression of the right iliac vein. However, no lymph nodes are palpable and a recent pelvic ultrasound examination showed a reduction in the previously demonstrated adenopathy. On physical examination you find pitting edema, erythema, increased warmth of the right calf (diameter 3.5 cm greater than that of the left calf), and tenderness with palpation of the popliteal vein. You apply a clinical prediction rule6 and conclude that the probability of proximal DVT is very high. Methods Search Strategy We conducted a MEDLINE search to retrieve all relevant articles pertaining to the clinical assessment of patients with suspected DVT. MEDLINE was searched from 1966 to April 1997 using Medical Subject Headings, EXP (explode) thrombosis (tw [textword]) and (EXP physical examination or EXP diagnostic tests or EXP sensitivity and specificity) and EXP phlebography. This was limited to human and English-language studies. One hundred fifteen articles were retrieved (available on request from the senior author); 68 articles that dealt with the diagnosis of DVT were selected for complete review. The bibliographies of the retrieved articles were examined for additional relevant articles. Only 5 studies provided information on the relationship between clinical findings and venographic confirmation of DVT.3,4,6,12,13 These studies were graded based on their methodologic quality using a standard scoring system.14 Principles of Diagnosis of DVT The diagnostic assessment of patients with suspected DVT has evolved over the past 2 decades from reliance on clinical symptoms and signs alone to heavy reliance on objective diagnostic tests.15 Results Clinical Assessment Over the past 30 years, the clinical assessment in patients with suspected DVT has been refined and now includes a careful review of risk factors, symptoms, and physical signs.5,16-18 Risk factors for DVT include immobility, paralysis, recent surgery and/or trauma, malignancy, cancer chemotherapy, advancing age (ie, >60 years), family history of venous thromboembolism, pregnancy, and estrogen use.19,20 In a recent prospective cohort study, 426 consecutive outpatients referred by general practitioners to a tertiary care thrombosis unit were assessed for DVT risk factors, and in approximately half of the patients with confirmed DVT, a major risk factor (immobility, trauma, and/or recent surgery) was present.19 The odds ratios for other risk factors independently associated with the presence of DVT, including male gender, age greater than 60 years, cancer, heart failure, systemic lupus erythematosus, and lower limb arteriopathy, are presented in Table 1. Commonly reported symptoms in patients with suspected DVT include leg pain, swelling, and other signs, such as pitting edema, warmth, dilated superficial veins, and erythema.3-5 Unfortunately, these findings are neither sensitive nor specific for DVT and may be caused by other disease processes,5,16 such as leg trauma, cellulitis, obstructive lymphadenopathy, superficial venous thrombosis, postphlebitic syndrome, or Baker cysts.6,21 The odds ratios for these factors range from 1.6 to 4.3.19 Furthermore, DVT can coexist with each of these processes. For example, the finding of a Baker cyst on an ultrasound examination does not rule out the presence of DVT.21 Traditionally, the routine physical examination in patients with suspected DVT included a careful inspection of the leg, measurement of the leg circumference, and elicitation of Homans sign,22 which refers to the development of pain in the calf or popliteal region on forceful and abrupt dorsiflexion of the ankle with the knee in a flexed position. Early studies evaluating the properties of individual physical signs such as these to diagnose DVT showed that they were inaccurate.3,4 In a study by O'Donnell et al,3 102 patients who presented to the outpatient departments of 2 tertiary care hospitals with suspected DVT underwent a clinical assessment and venography. A combination of clinical signs and symptoms that included tenderness, swelling, redness, and the assessment of Homans sign could not adequately differentiate patients with or without DVT. The sensitivity of the clinical examination in this study was 88% (95% confidence interval [CI], 77%-97%) and the specificity was only 30% (95% CI, 18%-40%). Haeger4 conducted a prospective study of 72 outpatients who presented with suspected DVT to a thrombosis clinic, were examined by 1 or 2 experienced surgeons, and underwent venography. No differences in the presenting symptoms or physical signs were identified between those with or without venographically confirmed DVT. The sensitivity of the clinical examination in this study was 66% (95% CI, 50%-82%) and the specificity only 53% (95% CI, 38%-69%). In a study by Molloy et al,12 100 patients with a clinical diagnosis of DVT who were referred to the radiology department of a general hospital were studied; the sensitivity of the clinical examination was 60% (95% CI, 45%-75%) and the specificity was 72% (95% CI, 60%-83%). Overall, these symptoms and signs occur in similar frequency in symptomatic patients with and without DVT (Table 2). The results of these studies led to a shift away from the clinical examination to a heavy reliance on noninvasive objective tests for patients with suspected DVT. More recently, in a retrospective chart review by Landefeld et al13 of 354 inpatients and outpatients with suspected DVT who underwent venography, there were 5 clinical findings independently related to the presence of proximal DVT: swelling below the knee, swelling above the knee, recent immobility, cancer, and fever. These factors were determined by using multiple linear regression, were found to be significantly associated with the presence of proximal DVT in 236 patients, and then were confirmed in the remaining 119 patients. Overall, the sensitivity of a positive clinical examination (associated with the presence of 1 or more independent predictors) was 96% (95% CI, 92%-100%) and the specificity was 20% (95% CI, 15%-25%). The frequency of signs and symptoms seemed to predict the presence of proximal DVT; where the absence of any findings was associated with less than a 5% chance of proximal DVT, and the presence of 2 or more clinical findings was associated with a 46% chance of proximal DVT. This was the first study to demonstrate the potential role of a clinical prediction guide in patients with suspected DVT. The likelihood ratio estimates for the clinical assessment based on the 4 studies described above are shown in Table 3. Recall that a likelihood ratio expresses the odds that a given finding on the history or physical examination would occur in a patient with the target disorder as opposed to a patient without it. Given a likelihood ratio above 1.0, the probability of disease (in this case DVT) increases when the finding is present, as the finding is more likely among the patients with the disease than among those without. When the likelihood ratio is below 1.0, the probability of disease declines as the finding is less likely to occur among patients with the disease than those without.23 Objective Assessment Venography is the reference standard for the diagnosis of DVT, and it is highly accurate for both proximal and calf DVT.24 However, venography is invasive, expensive, technically inadequate in about 10% of patients (either because of an inability to cannulate a vein or lack of adequate visualization of the deep veins), and may induce DVT in approximately 3% of patients.25 This led to the evaluation and validation of 2 noninvasive tests: impedance plethysmography and compression ultrasonography. These tests have proven to be sensitive to proximal, but not to calf vein thrombosis. Impedance plethysmography reliably detects occlusive thrombi of the proximal veins (popliteal, femoral, or iliac veins) but is less reliable at detecting nonocclusive proximal DVT, and is insensitive to calf DVT.26-29 Impedance plethysmography does not allow direct visualization of the veins, but suggests that DVT is present when significant outflow obstruction is present, particularly in the absence of a comorbid condition that might cause a false-positive result (ie, extrinsic venous compression or conditions associated with elevated central venous pressure).15 Although studies before 1990 reported that impedance plethysmography detected over 90% of proximal DVT, more recent studies reported sensitivities for proximal DVT of about 70%.30-32 This apparent decrease in sensitivity is probably caused by changes in referring patterns to speciality centers with a strong interest in DVT.33 Compression ultrasonography assesses compressibility of the femoral and popliteal veins and is highly sensitive and specific for detecting proximal DVT (noncompressibility is diagnostic of DVT, whereas compressibility excludes DVT).6,15,34-36 Neither impedance plethysmography nor compression ultrasonography reliably detects isolated calf vein thrombosis.37 It should be noted that while the specificity of compression ultrasonograpy and impedance plethysmography for DVT remains high in both symptomatic and asymptomatic patients, the sensitivity declines dramatically when impedance plethysmography and compression ultrasonography are used to evaluate asymptomatic patients (ie, 22% and 58%, respectively) vs symptomatic patients (ie, 96 % and 96%, respectively).38 Several diagnostic algorithms using serial compression ultrasonography or impedance plethysmography have been evaluated and validated in large clinical trials.26,29,34-36,39-44 Although compression ultrasonography appears to be more accurate than impedance plethysmography, serial testing with either is acceptable in patients with suspected DVT.39,45 Therefore, as most clinicians consider clinically important proximal DVT excluded by normal impedance plethysmography or compression ultrasonography on the day of presentation, anticoagulants can be safely withheld in such patients, as the probability of suffering from proximal DVT is less than 2% in the following 3 months.46 If the initial test results are normal, repeat testing over the next 5 to 7 days is recommended; if they become abnormal during this period, extending proximal DVT is likely and an anticoagulant therapy should be initiated. However, impedance plethysmography and compression ultrasonography have limitations too, such as availability, and the inconvenience and expense of repeat testing. Recently the D-dimer assays have been demonstrated to be useful adjuncts to noninvasive testing for suspected DVT because they are highly sensitive and, therefore, have high negative predictive values.47-49 D dimer is formed when crossed-linked fibrin contained within a thrombus is proteolyzed by plasmin. Various D-dimer assays are available, including enzyme-linked immunosorbent assays, latex agglutination assays, and a whole blood agglutination test.48 The whole-blood agglutination assay appears to be best for exclusion of DVT, since it is suitable for individual testing (unlike enzyme-linked immunosorbent assays), and has high sensitivity and reasonable specificity. Recent studies show that DVT can be reliably excluded in patients with suspected DVT who have a normal impedance plethysmograph and a normal D dimer (using the SimpliRed assay) and that such results occur in about two thirds of patients.47 This supports the role of the SimpliRed assay as a simple and rapid adjunct to noninvasive tests for the exclusion of clinically important DVT.47,48 For a summary of diagnostic algorithms for patients with suspected DVT see Table 4. Clinical Prediction Guide Recently, the clinical assessment of patients with suspected DVT was reevaluated. This was sparked by 2 observations that many patients with a high pretest probability (using clinical judgment) and a normal impedance plethysmograph had proximal DVT,30 and that the pretest probability of patients had an important influence on diagnosing PE, a closely related disease. For example, in patients with a low pretest probability and a high probability lung scan, the prevalence of PE was approximately 50% to 60%.50 These results generated the hypothesis that when pretest probability and further tests are concordant, DVT can be ruled in or out, whereas when they are discordant, further tests are necessary. Development of a Clinical Prediction Guide Recently, a clinical prediction guide that seeks to standardize the estimation of the pretest probability among clinicians was developed6 and is described below. This model enables clinicians to reliably stratify patients with suspected DVT into high, moderate, or low probability groups by following uniform criteria. After a review of the literature3,4,8,15,19 and input from experienced thrombosis investigators, categories deemed to be important in the estimation of a patient's pretest probability were considered and categorized as follows: (1) signs and symptoms of DVT, (2) risk factors for DVT, and (3) the presence or absence of diagnoses that were deemed at least as likely as DVT to explain the patient's symptoms. These include musculoskeletal injuries, cellulitis, and prominent lymphadenopathy of the inguinal area. The clinical prediction guide uses a scoring system that combines important symptoms and signs, risk factors for DVT, and the presence or absence of an alternative diagnosis. The results stratify patients with suspected DVT into low, moderate, or high probability groups. The original clinical prediction guide was initially developed in a training set of 100 outpatients at a thrombosis referral center, at McMaster University, Hamilton, Ontario, who presented with suspected DVT. All patients underwent venography, and a simple regression model determined the relative importance of individual and various clusters of factors to predict the probability that a patient suffered from DVT. The clinical prediction guide was then prospectively validated in a test set of 529 patients who presented with suspected DVT to 3 tertiary care referral centers, 2 in Hamilton and 1 in Padua, Italy.6 Clinicians recorded their assessment of pretest probability of DVT, then all patients underwent venography and compression ultrasound examination. This model cannot be applied to certain subgroups of patients who were excluded from the study, such as those with previous venous thromboembolism, those with concomitantly suspected PE, pregnant women, or patients receiving treatment with anticoagulants. Using the clinical model, eligible patients were initially stratified into low, moderate, or high pretest probability groups. Although individual physical findings on their own are not predictive of DVT, when specific physical signs are incorporated into the clinical prediction guide they contribute to the generation of the pretest probability of DVT. In Table 5, the physical signs and the scoring system of the clinical prediction guide are outlined. The physical signs classified as major points include localized tenderness to palpation along the distribution of the deep venous system; thigh and calf swelling—indicating that the entire leg has an increased diameter when compared with the asymptomatic side; and calf swelling in which the calf is measured approximately 10 cm below the tibial plateau (at the tibial tuberosity) and is considered present if the difference between calf diameters is greater than 3 cm. Minor points include the presence of a unilateral pitting edema of the leg using standard assessment measures; the presence of dilated superficial veins (nonvaricose) that persist with elevation in the lower limb or if present in any new pattern in the groin region on the symptomatic leg only; and the presence of diffuse or streaking erythema. The test-set confirmed that the clinical model could reliably classify patients into high, moderate, and low probability groups. The prevalence of all DVT (proximal and calf) using the venogram as the criterion standard in patients who were classified by the clinical model into the high probability strata was 85%, compared with 33% in the moderate probability and 5% in the low probability categories. The positive likelihood ratios for the high-, moderate-, and low-risk categories are 3.3 (95% CI, 2.6-4.3), 1.3 (95% CI, 1.0-1.7), and 0.2 (95% CI, 0.1-0.3), respectively. The specificity of compression ultrasonography to detect proximal DVT in all strata was between 98% and 100%. When interpreted in conjunction with pretest probability, the ability of compression ultrasonography to reliably diagnose DVT decreased as the pretest probability declined. The sensitivities of compression ultrasonography in the high, moderate, and low strata were 94%, 83%, and 80%, respectively. The corresponding likelihood ratios for compression ultrasonography in pretest probability strata are provided in Table 6. By combining pretest probability and compression ultrasonography results, the posttest probabilities of DVT for each possible combination of results were generated. In the high pretest probability strata, an abnormal compression ultrasonogram resulted in a 100% posttest probability; in the moderate strata, a 96% posttest probability; and in the low strata, a 63% posttest probability. In patients whose compression ultrasonogram was normal, the posttest probabilities of DVT in the high, moderate, and low strata were 24%, 5%, and less than 1%, respectively. The original clinical prediction guide was recently simplified using stepwise logistic regression and reevaluated.51 Recent trauma, family history, erythema, and recent hospitalization within the previous 6 months did not remain in the simplified model, which in combination with compression ultrasonography was recently prospectively tested in 593 patients with suspected DVT who were referred to tertiary care thrombosis clinics51 (Table 7). Similar to the original clinical prediction guide, the simplified guide was able to reliably stratify patients into high, moderate, or low probability groups, with corresponding prevalences of DVT of 75% (95% CI, 63%-81%), 17% (95% CI, 12%-23%), and 3% (95% CI, 1.7%-5.9%), respectively. These data support the use of a clinical prediction guide to simplify the diagnostic approach for patients with suspected DVT (Figure 1). In patients with a high or moderate pretest score who have an abnormal compression ultrasonogram, DVT can be reliably diagnosed (positive likelihood ratios of ∞ and 72, respectively) and treatment should be initiated. In patients with a low pretest probability of DVT who have a normal compression ultrasonogram (negative likelihood ratio of 0.2), DVT can be reliably excluded without further testing. For patients with discordant results (ie, high pretest probability and normal compression ultrasonogram, or low pretest probability and an abnormal compression ultrasonorgram), further testing is recommended (ie, venography or serial compression ultrasonography). Patients with a moderate pretest probability and a normal ultrasonogram have a 5% probability of having DVT and a repeat compression ultrasound examination in 7 days is recommended. Back to the patient The patient described in the "Clinical Scenario" section is a 55-year-old woman who presents with suspected DVT. Using the clinical prediction guide checklist found in Table 5, you determine that she has 5 clinical features predictive of DVT: a diagnosis of active cancer, calf swelling, erythema, localized tenderness along the popliteal vein, and pitting edema of the symptomatic leg. Although the possibility of enlarging pelvic lymph nodes in the right inguinal area offers a potential alternative diagnosis, you note that a recent pelvic ultrasound report indicates that these nodes have shrunk, rendering this a less likely alternative diagnosis. Therefore, with 5 clinical features of DVT, and no convincing alternative diagnosis, following the approach of the clinical prediction guide you conclude that she has a high clinical probability of suffering from acute DVT. The next step is to perform a compression ultrasound examination, and, if the results are abnormal, the posttest probability of DVT being present approaches 100%. However, if the ultrasonogram is normal (ie, showing normal compressibility of the proximal veins), the posttest probability is approximately 24%, and further testing with venography would be required. Conclusions Although physical findings of patients with suspected DVT are not useful on their own, this state-of-the-art clinical prediction guide that includes factors from both the history and physical examination is able to assist in the diagnosis of DVT. When used in combination with noninvasive tests, such as compression ultrasonography, it can simplify and reduce the expense of management strategies. The bottom line Individual symptoms and signs on their own are not useful to diagnose DVT. 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Journal

JAMA – American Medical Association

Published: Apr 8, 1998

Keywords: deep vein thrombosis,ultrasonography, compression

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