Intracytoplasmic sperm injection for treatment of infertility due to acrosomal enzyme deficiency

Objective: To determine whether absence of fertilization in IVF associated with an acrosomal enzyme defect (hyaluronidase deficiency) results from a simple mechanical block to sperm penetration or from a more serious sperm abnormality. Design: Nonrandomized, prospective study. Setting: Toronto Center for Advanced Reproductive Technology, a tertiary referral center for infertility associated with The University of Toronto. Patients: One hundred twenty-two couples about to undergo intracytoplasmic sperm injection (ICSI) were selected. Thirty-six of the studied couples had failed to fertilize in prior IVF cycles. Interventions: Hyaluronidase activity was measured in the semen samples provided for ICSI using a zymogenic assay. Intracytoplasmic sperm injection was performed in all couples using standard techniques. Results: Forty-eight of 122 semen samples had poor or absent semen hyaluronidase activity. All 48 samples resulted in successful fertilization with ICSI in the present study. The average fertilization rate per oocyte was 59.43% in couples in whom the male partner had low semen hyaluronidase activity and 55.85% in whom the male had normal hyaluronidase activity. The ET rate per cycle was 100% and 95% and pregnancy rates per cycle were 26% and 25% in cycles with poor and normal semen hyaluronidase activity, respectively. Unlike routine IVF, no statistical correlation was found between semen hyaluronidase activity and the fertilization rate in ICSI. Conclusion: Our results indicate that semen hyaluronidase deficiency is associated with a simple mechanical block to fertilization. In addition, the measurement of semen hyaluronidase activity can provide a reliable means for selecting couples who would benefit from ICSI.