Significance of sperm characteristics in the evaluation of male infertility.

OBJECTIVE: To compare sperm characteristics among: patients undergoing infertility evaluation, patients with male factor infertility (MFI), healthy sperm donors, and men with proven fertility; to examine the overlap of sperm characteristics in all four of these groups; and to identify good discriminators of fertility versus infertility among sperm characteristics.
DESIGN: Retrospective study.
SETTING: Male infertility clinic at a tertiary care hospital. PATIENT(S): Proven fertile men (n = 56), normal donors (n = 91), men presenting for infertility evaluation (n = 406), and MFI patients (n = 166). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Routine semen analysis. RESULT(S): Using current World Health Organization (WHO) reference values, a large group of MFI patients presented with higher sperm concentration (27.5 x 10(6) to 99.2 x 10(6)), resulting in broader overlap with fertile men and poor sensitivity (0.48). Similarly, percentage normal morphology (%) using Tygerberg's strict criteria was low in most of the MFI patients (sensitivity 0.83), almost half of the fertile men also presented with abnormal morphology (specificity 0.51). Of all the variables examined, sperm motility (%) was superior, having minimum overlap range (lower and upper cut-off values 46% and 75%) and high sensitivity (0.74) and specificity (0.90). Areas under curve were higher for motility (0.90) and concentration (0.84) compared with morphology (WHO 0.65 and Tygerberg's strict criteria 0.74). CONCLUSION(S): Sperm motility and concentration provide more accurate information than morphology (WHO and Tygerberg's criteria) during infertility evaluation. Redefining the reference values for concentration and morphology may significantly increase the importance of routine semen analysis.