Prognostic value of the heterologous ovum penetration test for human in vitro fertilization.

In order to evaluate the prognostic value of the heterologous ovum penetration test (HOP-test) the results of this test were compared with the fertilization rate of human ova in a programme for in vitro fertilization and embryo transfer (IVF/ET). Sperm from 29 husbands (23 normozoospermic and 6 with an abnormal semen profile) were exposed on one occasion to approximately 30 hamster ova in the HOP-test and on 1 to 3 occasions to 1 to 4 preovulatory oocytes obtained from the respective wives. The mean penetration rate (+/- SEM) of the hamster ova was 43 +/- 4% (range: 0-62%) for the normozoospermic men, and 23 +/- 6% (range: 0-47%) for the men with abnormal semen profiles. In 20 out of 23 couples in which the husbands were normozoospermic, sperm penetrated the hamster ova as well as they fertilized human ova; however, in one couple, a false-positive result was obtained (penetration of the hamster ova and no fertilization of the human oocytes) and in one couple a false-negative result occurred. One negative IVF result was correctly predicted by the HOP-test. In the 6 patients with disturbed sperm motility no correct positive or negative results were obtained, whilst 4 false-positive and 2 false-negative results occurred using the HOP-test. Although the number of patients with disturbed sperm motility was small, the data suggest that the HOP-test is of limited value in predicting fertility in an IVF program for couples with reduced fertility.