Modification of the sperm penetration assay using human follicular fluid to minimize false negative results.

Controversy surrounds the hamster test because of its frequent lack of correlation with human in vitro fertilization (IVF). This may be due to the low percentage of acrosome-reacted sperm that results from the assay's methodology. With the use of human follicular fluid (hFF) to increase the proportion of acrosome reactions, the penetration rate was raised by an average of 38% in 74% of samples from the subfertile men tested. Consistent enhancement prevailed in three subfertile patients, who were tested over a 6-month period. Brief exposure of the spermatozoa to follicular fluid may more accurately simulate the human IVF condition leading to capacitation and perhaps minimizing false-negative sperm penetration assays (SPAs).