Offering excess oocyte aspiration and vitrification to patients undergoing stimulated artificial insemination cycles can reduce the multiple pregnancy risk and accumulate oocytes for later use.

The prevention of multiple pregnancies remains a major challenge in patients treated with ovarian stimulation prior to intrauterine insemination (IUI). The pilot study presented here investigates whether multiple pregnancies can be minimized by a microscopically confirmed aspiration of oocytes from supernumerary follicles immediately before intrauterine insemination and evaluates the benefit of concomitant excess oocyte cryopreservation for future use. Thirty-four aspirations of supernumerary follicles were performed immediately prior to IUI in 31 patients undergoing ovarian stimulation. sIUI was only performed if cumulus-oocyte complexes were microscopically observed in the aspirated follicular fluid. All collected mature excess oocytes were cryopreserved using the vitrification technique. Only four sIUI procedures had to be cancelled due to failed oocyte retrieval or premature ovulation. IUI treatment resulted in a clinical pregnancy rate of 23.5% per cycle. All were singleton pregnancies. A total of 111 oocytes were cryopreserved. Patients with polycystic ovary syndrome (PCOS) had an average of 6.07 oocytes vitrified, whereas patients without PCOS had 1.3 oocytes vitrified per cycle. Microscopically confirmed collection of excess oocytes prior to stimulated IUI reduced cancellation rates, further reduced the risk for multiple pregnancy and may lead to future additional pregnancies because, based on current information, approximately 5% of the vitrified oocytes could potentially establish a pregnancy.