CONTRIBUTION OF THE MALE FACTOR TO UNEXPLAINED INFERTILITY - A REVIEW

The more exhaustive the evaluation of couples with unexplained inferti lity, the more likely is the opportunity for detecting the aetiologica l factor responsible for infertility. Transport of spermatozoa through the upper genital tract and their ability to fertilize the oocyte are two obscure areas for the conventional evaluation of infertility. Alt hough research in the former area is limited, there is indirect eviden ce that impaired sperm transport could be one of the causes of inferti lity in some couples with otherwise unexplained infertility. On the ot her hand, the availability of sperm function tests and the correlation of their results with in-vitro fertilization rates have allowed the d etection of a previously hidden male factor in couples with unexplaine d infertility. It has been demonstrated that couples suffering unexpla ined infertility have significantly lower in-vitro fertilization rates in comparison with patients with tubal problems. These results can be explained because several case control studies in patients with unexp lained infertility have reported defects in capacitation and sperm mot ion characteristics, binding of the spermatozoa to the zona pellucida, acrosome reaction, acrosin activity of the spermatozoa, and the abili ty of the spermatozoa to penetrate zona-free hamster oocytes. These ob servations suggest that methods for assessing the fertilizing capacity of the spermatozoa have to be incorporated in the evaluation of coupl es with unexplained infertility in order to amplify the scope of the w orkup and to better decide the appropiate treatment for these couples.