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 performed 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 significant 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, respectively, 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 binding test may be an efficient method to identify the most competent spermatozoa for ICSI.