Semen analysis and sperm function assays: what do they mean?

Appropriate laboratory testing is an integral component of the proper evaluation of the male presenting with infertility. This article reviews the semen analysis and sperm function assays. Sperm function testing is used to determine if the sperm have the biologic capacity to perform the tasks necessary to reach and fertilize ova and ultimately result in live births. For a sperm to be fertile in vivo, it must be able to traverse the cervical mucus and reach the ova. The sperm must undergo capacitation and the acrosome reaction, fuse with the oolemma, and incorporate into the ooplasm. Proper embryo development requires that functional DNA be delivered to the ooplasm. Defects in any of these steps may result in infertility. A variety of tests are available to evaluate different aspects of these functions. To accurately use these functional assays, the clinician must understand what the tests measure, what the indications are for the assays, and how to interpret the results to direct further testing or patient management.