Human sperm hyperactivation and acrosome reaction and their relationships to human in vitro fertilization.

OBJECTIVE: To determine the relationships between human sperm hyperactivation (HA) and acrosome reaction with fertilization of human oocytes in vitro. DESIGN: Prospective analysis of infertile patients undergoing IVF. SETTING: Tertiary center for infertility and assisted reproductive technology. PATIENTS: Fifty-two couples who underwent IVF or GIFT were studied. The male partners had normal semen parameters on routine analyses. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Sperm HA in seminal fluid and after 1 and 6 hours incubation in capacitation media; sperm acrosome reaction after 0, 6, and 24 hours' incubation in capacitation media; and fertilization rate of human oocytes. RESULTS: The percent spermatozoa with transitional HA after 6 hours of incubation correlated significantly with the fertilization rate of human oocytes. Multivariate discriminant analyses selected six sperm HA and acrosome reaction variables of predictive value in classifying semen samples that achieved fertilization rates above and below 70% threshold. Combination of the selected sperm HA and acrosome reaction variables in seminal fluid and after different times of incubation in capacitation medium classified the samples achieving good or poor fertilization rate with > 80% accuracy. CONCLUSIONS: Assessment of sperm HA and acrosome reaction may be of prognostic value in prediction of human oocyte fertilization rates.