Interpretation and misinterpretation of semen parameters.

Semen analysis, which is traditionally used to evaluate male fertility, may be misleading if sample is lost or inadequately mixed. A short or excessive abstinence period may cause a low count or a high count with low motility. Damage from low temperature or delay in evaluation may decrease the reported motility. Computer-assisted semen analysis has eliminated some of the variability and has allowed the evaluation of other sperm motion variables such as sperm velocity, linearity, maximum and mean amplitude lateral head displacement, and beat-cross frequency. These measurements may also occasionally be misleading. Other tests may give a better indication of the function of sperm. The hamster egg penetration test has been used but is technically difficult, and perhaps that is why there is controversy as to the clinical value of the test in predicting subfertile sperm despite normal conventional semen analysis. Some recent data suggest that the hypo-osmotic swelling test, which determines the functional integrity of the sperm membrane, may be the appropriate prognosticator. There is a need for further studies to define the best method to determine whether a male factor is responsible for a couple's infertility.