The predictability of subnormal penetrating capacity of sperm in cases of unexplained infertility.

Multivariate discriminant analysis has been used to determine the predictability of sub-normal penetrating capacity in cases of unexplained infertility. The product of this analysis was the identification of 7 discriminating variables, all of which described various aspects of the post-capacitation movement characteristics exhibited by the spermatozoa, omitting all reference to the conventional parameters of semen quality. On the basis of these discriminating variables, 90.9% of samples exhibiting penetration rates within the normal range were correctly predicted to be functionally competent. The same variables correctly identified only 60% of samples with impaired penetrating capacity, indicating that in the remaining 40%, defects are present in the spermatozoa which are not reflected in their motility patterns.