Use of the heterologous ovum penetration test to predict the fertilising capacity of human spermatozoa.

: The ability of human spermatozoa to penetrate zona-free hamster ova in a heterologous ovum penetration (HOP) test was compared with the fertilisation of human oocytes in 54 normospermic couples. Concordant results were seen in 45/54 (83%) cases. However, false-positive HOP test results occurred in 5/45 (11%) couples and false-negative results in 4/9 (44%) couples. The data suggest that a positive HOP test result is a good indication that fertilisation will occur, although a negative HOP test result does not necessarily mean that fertilisation will not take place.