Fertilization of supernumerary oocytes following gamete intrafallopian transfer (GIFT): correlation with outcome of GIFT treatment.

In the course of 280 consecutive gamete intrafallopian transfer (GIFT) attempts, supernumerary oocytes in excess of those transferred were inseminated in vitro. Pregnancy resulted in 31.1% of patients following the GIFT treatment. The overall in vitro fertilization (IVF) rate of supernumerary oocytes was significantly higher in those who became pregnant (41.2%) than in patients who did not (34.9%). However, the failure to fertilize any supernumerary oocytes was not significantly different between those becoming pregnant (27.6%) and those in whom the treatment failed (37.3%). Failure to fertilize any supernumerary oocytes in vitro was of a higher rate if suboptimal sperm preparation was used or if only one oocyte was left over for in vitro insemination following the GIFT treatment. We concluded that the in vitro fertilization rate was higher in the pregnant group, but the total failure to fertilize or the fertilization of any supernumerary oocytes does not predict the outcome of GIFT. Embryos resulting following fertilization of excess oocytes may be cryopreserved for subsequent use.