The infertile male--diagnosis.

PURPOSE To discuss a variety of tests used to diagnose the subfertile male and to impart based on clinical experience, reading, and personal research, this editor's view of the relative value of these tests. METHODS The tests discussed include motile density, sperm morphology, the hypo-osmotic swelling test, antisperm antibodies, sperm chromatin structure assay, DNA integrity tests, reactive oxygen species, sperm penetration assay, sperm-zona pellucida binding tests, sperm creatine kinase activity, plasma membrane mannose-ligand receptor assay, and nuclear morphology. RESULTS Except when extremely low (< 2.5 x 10(6)/ml) motile density does not identify the subfertile male very well. In contrast to other studies, my group's data suggest that neither low normal morphology by WHO standards or strict criteria identify the subfertile male. The best predictor of male subfertility is the hypo-osmotic swelling test when it is < 50%, which does not result in fertilization failure, but implantation failure. A high percentage of sperm coated by antisperm antibodies is very predictive of fertilization failure. CONCLUSIONS The physician must be careful when concluding that the male is subfertile or fertile based on standard tests of concentration, motility, and especially morphology.