THE USE OF ZONA-FREE AGED UNFERTILIZED HUMAN OOCYTES AS A PREDICTOR FOR SUCCESSFUL SUBZONAL INSEMINATION

Objective: To examine the reliability of the zona-free aged (1 day old ) human unfertilized oocyte sperm penetration assay for assessing sper m fertilizing ability and to determine the predictive value of this as say for subsequent subzonal insemination (SUZI) outcomes. Design: A to tal of 253 unfertilized oocytes from total fertilization failure patie nts and from good fertilization rate (>70%) patients in standard IVF w ere inseminated with donors' spermatozoa, and penetration rates were c ompared in each group. Two hundred seventy-two unfertilized oocytes fr om total fertilization failure, poor fertilization (<30%), and normal fertilization (>30%) were inseminated with husbands' spermatozoa, and penetration rates were compared between the three groups. In 29 patien ts, the results of the zona-free assay performed in previous IVF were compared with the fertilization rates of subsequent SUZI. Results: In the zona-free assay using donors' spermatozoa, there was no difference in penetration rates between the two groups (109/122, 89.3% versus 11 4/131, 87.0%). Penetration rates using partners' spermatozoa were posi tively correlated with fertilization rates in standard IVF (total fert ilization failure 34/75, 45.3%; poor fertilization 56/77, 72.7%; norma l fertilization 108/120, 90.0%). There was a significant difference in fertilization rates after SUZI between the patients with negative and positive penetration in zona-free assay (4/53, 7.5%, versus 54/174, 3 1.0%). Conclusion: The zona-free human oocyte assay may primarily refl ect sperm fertilizing ability. This assay also could be a reliable pre dictor for subsequent SUZI outcome.