Success rates following intracytoplasmic sperm injection are improved by using ZIFT vs IVF for embryo transfer

Purpose: The purpose of this study was to analyze whether the mode of embryo transfer (ZIFT vs IVF) affected the outcome in intracytoplasmic sperm injection (ICSI) cycles.Methods and Results: Eighty-two ICSI cycles (42 ZIFT and 40 IVF) were analyzed. Several variables, including patient age and weight, numbers of mature eggs collected, injected, and fertilized, fertilization rate, number of fertilized eggs obtained per cycle, numbers of zygotes/embryos transferred, clinical pregnancy rate, and implantation rate, were compared. Mean patient age and weight were identical. The mean number of mature eggs collected and injected and fertilization rate were significantly higher in the ZIFT group, however, the mean numbers of zygotes/embryos transferred were identical. The clinical pregnancy and implantation rates in ZIFT cycles (52.3 and 23.2% respectively) were significantly higher than in IVF cycles (17.5 and 9.7%).Conclusions: These data suggest that ZIFT is the more appropriate method for transfer of ICSI-derived embryos.