Oocyte Vitrification Is a Viable Option for Achieving Pregnancies and Preventing Multiple Gestation When Excess Oocytes Develop During Controlled Ovarian Hyperstimulation With Gonadotropins and IUI

Abstract

Background: The vitrification of oocytes for oocyte banking has been proposed as an alternative to embryo cryopreservation in women undergoing future chemotherapy or wanting to postpone child bearing, or as an alternative to collecting fresh donor oocytes in donor-egg IVF cycles. Objective: This study investigates the vitrification of mature MII oocytes to prevent multiple gestations. Materials and Methods: Women undergoing controlled ovarian hyperstimulation with gonadotropins and IUI who developed an excessive number of follicles consented to have excess eggs aspirated and vitrified for future in vitro fertilization in the event they did not become pregnant. Patients' eggs were aspirated using our standard egg retrieval protocol under conscious sedation and cultured for 1 hour in Sage fertilization medium, and the cumulus cells were then removed. Mature oocytes were vitrified using the Cryoleaf Vitrification System from Medicult. Oocytes were stored for at least 1 month after retrieval. If the patient failed to conceive with IUI, then using our standard frozen embryo transfer protocol, she were given endometrial Support with sequential estrogen and progesterone supplementation. Oocytes were warmed using the Medicult warming protocol and were then incubated in Sage cleavage medium for 4 hours before undergoing ICSI. Results: Fifteen patients with an average age of 30.8 years were converted. A total of 152 oocytes were vitrified with an average of 10.1 per patient. Eleven patients returned for a frozen embryo transfer. Eighty-one oocytes were warmed, of which 63 (77.8%) survived. Following ICSI, 43 oocytes (68.3%) fertilized, and 36 of 43 (83.7%) cleaved. Three patients did not have an embryo transfer owing to failed fertilization, no cleavage, or poor embryo quality. Embryos were transfered on day 2 or 3 with a resultant positive pregnancy rate of 62.5% (5/8) overall. Three patients (37.5%) had an ongoing pregnancy at 12 weeks with an implantation rate of 13.6% per embryo transfered. One healthy female has been born to date. Conclusion: The vitrification of oocytes has been successful in establishing reasonable pregnancy rates in patients converted from IUI to prevent multiple gestations. Subsequent studies using donated oocytes are underway.