Complete failure of fertilization in couples with unexplained infertility: Implications for subsequent in vitro fertilization cycles

Objective: To determine whether complete failure of fertilization of oocytes in couples with unexplained infertility persists during subsequent in vitro fertilization (IVF) cycles. Design: A retrospective study of 120 cycles of IVF in 44 couples with unexplained infertility and complete failure of fertilization during their first IVF trial. Setting: In vitro fertilization unit of the Sheba Medical Center. Patients: Forty-four couples undergoing IVF for unexplained infertility. Main Outcome Measure(s): Fertilization rate of retrieved oocytes and pregnancy rate. Results: Of the initial 44 couples, 37 underwent additional IVF cycles and 30 (81.1%) achieved fertilization. Seven patients conceived during the study period as a result of IVF and two conceived spontaneously. Conclusions: Complete failure of fertilization does not necessarily persist during subsequent IVF cycles. Therefore, at least two more IVF cycles should be attempted before reverting to other therapeutic options. However, although fertilization can be achieved in most couples, the mean oocyte fertilization rate during subsequent cycles in this group is low. This suggests an underlying undiagnosed pathology of oocyte/sperm interaction in some of these patients.