Disordered zona pellucida–induced acrosome reaction and failure of in vitro fertilization in patients with unexplained infertility

Abstract

Objective To determine the relationship between the zona pellucida (ZP)–induced acrosome reaction (AR) and fertilization rate and pregnancy rate in standard IVF and the frequency of disordered ZP-induced AR (DZPIAR) in patients with unexplained infertility. Design Prospective study. Setting Academic research and teaching tertiary hospital. Patient(s) Patients with unexplained infertility with normal semen analysis. Intervention(s) None. Main outcome measure(s) Semen analysis, the ZP-induced AR, and measurements of fertilization rate and pregnancy rate with in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). Result(s) A statistically significant correlation was found for the ZP-induced AR and fertilization rate with standard IVF (n = 65). Patients with DZPIAR (ZP-induced AR of ≤16%) had an average fertilization rate of 23%, in contrast to patients with ZP-induced AR of >16%, who had an average fertilization rate of 61%. The sensitivity and specificity of DZPIAR for prediction of IVF rates <30% and ≥30% were 80% and 86%, respectively. Of 260 patients screened, the frequency of DZPIAR was 29%. Ten patients with DZPIAR had an average fertilization rate of 15% and no pregnancy with initial IVF cycles, and a fertilization rate of 61% (with three live-birth pregnancies) with subsequent ICSI cycles. Another 33 patients with DZPIAR were treated with ICSI alone, with an average fertilization rate of 71% and a live-birth pregnancy rate of 17% per embryo transfer. Sixteen of the patients had live-birth pregnancies (including one set of twins) after undergoing an average of 3.2 embryo transfers. Conclusion(s) Patients with DZPIAR have a low or zero fertilization rate with standard IVF but high fertilization and pregnancy rates with ICSI. Up to 29% of patients with unexplained infertility with normal semen analysis may have this condition, which should be diagnosed and treated with ICSI rather then standard IVF.