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

Objective: To evaluate the results of a novel protocol that allows to rescue IVF unfertilized oocytes by intracytoplasmic sperm injection (ICSI).

Design: Prospective clinical trial.

Setting: Private 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.