Evaluation of human sperm membrane integrity using the water test and the hypoosmotic test

The objective of the study was to compare the water test and the hypoosmoti c test (HOS) in the assessment of the human sperm membrane. A total of 686 semen samples from human male donors were subjected to water and HOS tests after routine semen evaluation. The mean percentage of swollen spermatozoa was 71.8 +/-9.6% in the HOS test and 67.8 +/-9.4% for the water test; these values were not statistically different. The correlation of coefficients b etween the water test and the HOS test was highly significant whether the v alues for the HOS test were higher or lower than 60% (P<0.001). A poor corr elation was obtained when the two tests were compared for sperm counts eith er higher or lower than 20 x 6 ml(-1) and when the results for both tests w ere compared with the percentage of eosin-Y staining spermatozoa. A poor co rrelation was also obtained when the results of each test were compared wit h eosin-Y staining spermatozoa in normal and abnormal semen samples. The co efficient of regression between the two tests showed a high correlation (P< 0.001). In conclusion, even though a high correlation between the HOS test and water test was observed in this study, it is not possible to recommend assessment of sperm membrane integrity using the water test and the consequ ent replacement of the HOS test in routine practice. Further studies are ne cessary to establish the best test for sperm vitality.