THE USE OF THE STIMULATED ACROSOME REACTION TEST AS A TEST OF FERTILIZING ABILITY IN HUMAN SPERMATOZOA

Objective: To assess if patients who do not fertilize human oocytes in vitro can be identified by a lack of acrosomal response of their sper matozoa to stimulation by the calcium ionophore A23187. Design: The st imulated acrosomal response for all patients was calculated. Those not achieving fertilization were compared with a normogram constructed fr om donors and patients who achieved fertilization; the 0.5th centile ( 31.3% increase in the number of spermatozoa reacted) was used as a dis criminant point. Patients: Fifty-four IVF patients and 15 fertile sper m donors. Setting: An outpatient based IVF program. Interventions: Acr osome reaction stimulated by 2 hours incubation in a 5-mumol/L solutio n of the calcium ionophore A23187. Results: Patients who fertilized oo cytes responded as donors. Eight of 16 patients failing to fertilize o ocytes showed a minimal increase in the number of acrosome-reacted spe rmatozoa (mean [+/- SD] rise 6.3% +/- 10.3%). An acrosomal response of <31.3% predicts fertilization failure in 100% of cases. Conclusions: Failure of the acrosome to react is responsible for some failure of IV F.