Stability of the Hypoosmotic Swelling Test Over Time
Abstract
The results of the sperm count, motility, and hamster oocyte penetration (SPA) tests have been found to vary greatly in individuals who have had tests performed on more than one occasion. The study presented herein was designed to evaluate the stability of the hypoosmotic swelling (HOS) test over time. A total of 444 patients were classified into categories according to the time interval between HOS tests: 0–90 days ( n = 267), 91–180 days ( n = 35), 181–270 days ( n = 37), 271–360 days ( n = 30), 1–2 years ( n = 54), and >2 years ( n = 21). A paired t test was used to compare mean HOS scores. The correlation between the HOS test of the first specimen and the HOS of the second specimen was calculated. For those who had 2 tests the only significant difference was found in the >2 year group (69.67 ± 9.13 vs. 64.23 ± 12.83%), p <. 05. When comparing the first and third HOS test in 74 patients, there was a significant ( p <. 05) decrease in the later test when the interval was greater than 270 days. The difference was not significant when the HOS results were classified as subnormal (<50%) and normal (>50%) for that same time period. It would appear that this test is reproducible, rarely fluctuates, but tends to become less dependable over longer intervals of time.