Effect of reduced oocyte aging on the outcome of rescue intracytoplasmic sperm injection

ObjectiveTo evaluate the results of a novel protocol that allows to rescue IVF unfertilized oocytes by intracytoplasmic sperm injection (ICSI).DesignProspective clinical trial.SettingPrivate reproductive medical center.Patient(s)Thirty patients undergoing IVF.Intervention(s)Controlled ovarian stimulation (COS), conventional IVF, rescue ICSI, embryo culture, and embryo transfer.Main Outcome Measure(s)Identification of unfertilized IVF oocytes 6 hours after insemination and fertilization, and developmental rates of those oocytes after rescue microinjection, as well implantation and pregnancy rates (PR).Result(s)All oocytes (392) from 30 patients were inseminated with standard IVF 3 hours after ovum pick-up. Polar body (PB) status was checked at decumulation and rechecked 3 hours later. Eighty-two oocytes were fertilized after IVF alone and 184 nonactivated oocytes (failed fertilization) were rescue microinjected and 166 of them fertilized (20 patients). Cleavage stage on day 2 was significantly more advanced and embryo grade was higher after standard IVF fertilization than after rescue ICSI. Eight of the 30 embryos transferred were implanted in the IVF-only patients (27%) and 8 of 68 embryos in the rescue ICSI patients (12%).Conclusion(s)Rescue ICSI of unfertilized IVF oocytes 6 hours after insemination (9 hours after egg retrieval) can provide normal fertilization, embryo development, and pregnancy; however, corresponding outcome parameters tend to be impaired in comparison to the standard IVF fertilization results.