Utrastructural analysis of asthenozoospermic ejaculates in the era of assisted procreation.

To define by transmission electron microscopy (TEM) analysis, the prevalence of sperm tail defects of genetic origin among men suffering for a reduced or absent sperm motility. A retrospective study. Andrology Clinic, University of L'Aquila, Italy. The 120 ejaculates of infertile men with a forward motility (FM) < or =20% were compared to 200 ejaculates with a FM >20%. All ejaculates had a sperm vitality >50%. Some 25-50 tails were analyzed by TEM in each ejaculate. Receiver operating characteristics (ROC) analysis was applied by plotting the FM of cases with or without genetic tail defects detected by TEM. The area under the ROC curve was 0.96 (95% confidence interval 0.92-0.98). The positive predictive accuracy for genetic tail defects in ejaculates with 0% FM was 46%. Three of 17 cases with genetic tail defects were classified as false negative when TEM analysis was restricted to ejaculates with 0% FM. A FM < or =7%, allowed the identification of all cases with genetic tail defects. The TEM analysis identifies sperm tail defects of genetic origin and should be restricted to ejaculates with severe asthenozoospermia (< or =7% motile sperm) and sperm vitality >50%.