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 spermatozoa to stimulation by the calcium ionophore A23187.

DESIGN

The stimulated acrosomal response for all patients was calculated. Those not achieving fertilization were compared with a normogram constructed from donors and patients who achieved fertilization; the 0.5th centile (31.3% increase in the number of spermatozoa reacted) was used as a discriminant point.

PATIENTS

Fifty-four IVF patients and 15 fertile sperm donors.

SETTING

An outpatient based IVF program.

INTERVENTIONS

Acrosome reaction stimulated by 2 hours incubation in a 5-mumol/L solution of the calcium ionophore A23187.

RESULTS

Patients who fertilized oocytes responded as donors. Eight of 16 patients failing to fertilize oocytes showed a minimal increase in the number of acrosome-reacted spermatozoa (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 IVF.