Vitrification of oocytes produces high pregnancy rates when carried out in fertile women

Abstract

Objective: To determine the efficiency of our vitrification technique when applied in young fertile women.

Design: Clinical research and application.

Setting: In vitro fertilization center.

Patient(s): Twenty-one women were recruited from the navy community with 19 patients finishing the study.

Intervention(s): Vitrified oocytes with use of the electron microscopic grid method were warmed 6 months after vitrification. Surviving metaphase II oocytes were microinjected for fertilization, and clinical results were evaluated.

Main outcome measure(s): Survival, fertilization, and cleavage rate. Pregnancy and implantation rate.

Result(s): Three hundred ninety-five oocytes were warmed, of which 320 oocytes (81.0%) survived. Two hundred eighty-five metaphase II oocytes were microinjected for fertilization; 206 of them (72.3%) fertilized, and 53 embryos were transferred to 19 patients (in 20 warming cycles). Twenty-four of 53 transferred embryos (45.3%) implanted as confirmed by ultrasound examination. Of the 20 transfers, 16 resulted in clinical pregnancy (80%), 3 miscarried (15%), and 13 (65%) went on to produce 20 live births, respectively. This is much higher in comparison with our previous data using supernumerary oocytes where the rates of implantation and pregnancy were 6% and 21%. Live-birth rates per warmed oocyte and per injected oocyte were 5.1% and 7.2%, respectively.

Conclusion(s): High pregnancy and implantation rates were observed after 6 months of cryopreservation by vitrification when oocytes from fertile woman were used. Proper screening of candidates for oocyte cryopreservation is of crucial importance to assure a favorable pregnancy outcome.