Improving the predictive value of the hypoosmotic swelling test in humans.

Using a combined hypoosmotic swelling-eosin (HOS-E) technique in human semen samples, we evaluated the frequency of dead swollen spermatozoa (dHOS) after 10 and 30 minutes of incubation, the correlation between total HOS-reactive (tHOS) and viable HOS-reactive (vHOS) spermatozoa with other seminal parameters, and the possibility that dead spermatozoa react to HOS. We obtained the following results: [1] some dead spermatozoa swell under hypoosmotic conditions and [2] HOS-E results correlate strongly with other seminal parameters. We recommend that HOS be performed after 10 minutes of incubation because [1] the increase in the incubation time enhances the percentage of dHOS, [2] there are no differences in vHOS percentages between 10 and 30 minutes, and [3] correlation coefficients between vHOS and tHOS with other parameters are very similar at 10 or 30 minutes of incubation.