Outcome of ICSI using zona pellucida-bound spermatozoa and conventionally selected spermatozoa

This study aimed to investigate whether the spermatozoa-zona pellucida binding test is able to select spermatozoa with higher fertilization potential and higher rate of successful embryo development. This prospective study was per- formed with metaphase II (MII) oocytes retrieved from couples undergoing intracytoplasmic sperm injection (ICSI) cycles. For each patient, half of the MII oocytes were injected using a routine ICSI method (control group, n = 194) while the other half were injected with previously zona pellucida-bound spermatozoa (ZP-binding group, n = 194). Fertilization rate, high-quality embryo rate, and embryo transfer rate were compared between the groups. No sig- nificant difference was observed among the groups in the fertilization rate (76.8% versus 77.3% for control and ZP-binding groups, respectively). However, an increased percentage of high-quality embryos was observed when zona pellucida-bound spermatozoa were injected (70.0% versus 83.3% for control and ZP-binding groups, respec- tively, P = 0.003). Moreover, when embryo selection was performed while ignoring experimental group origin, embryos from the ZP-binding group were more commonly selected for transfer (43.6% versus 54.6% for control and ZP-binding groups, respectively, P = 0.004). These findings suggest that the spermatozoa-zona pellucida bind- ing test may be an efficient method to identify the most competent spermatozoa for ICSI.