Clinical Application of Oocyte Cryopreservation I. Pregnancy and Delivery of Vitrified Human Oocytes in ART Program

난자동결보존의 임상적 응용 I. 유리화 난자동결 보존에 의한 임신과 분만

This study was performed to evaluate whether vitrification method using ethyle glycol and eletron microscopic (EM) grid could be used far the cryopreservation of human oocytes in ART program. Surplus oocytes were obtained from consented IVF patients. These surplus human oocytes were frozen with our vitrification method, Oocytes were exposed to 1.5M ethylene glycol (EG) in DPBS far 2,5 minutes, followed by 5.5M EG plus 1.0M Sucrose in DPBS for 20 seconds. Then oocytes were transferred onto the EM grid and the grid was plunged into LN2 for storage. For thawing, oocytes containing EM grid were sequentially transferred in 1.0M, 0.5M, 0.25M, 0.125M and 0 M sucrose in DPBS solution at the intervals of 2.5 minutes. Thawed and survived oocytes were provided for ICSI. Embryos from vitrified oocytes were transferred to uterus of the patient on 4 to 5 days after ovulation in natural cycles of on 15 to 17 day of hormone replacement cycles. A total of 370 oocytes from 26 patients were thawed and 159 (43.0%) of them survived. One hundred thirty four oocytes (84.3%) were fertilized normally and 126 pre-embryos were transferred to 26 patients, resulting in 5 clinical pregnancies. The pregnancy rate per transfer was 19.2% and implantation rate was 4.0%. Among the five pregnant, 4 patients delivered 4 healthy babies and the one patient was 32-week ongoing pregnancy. From this results, vitrification using ethylene glycol as cryoprotectant and EM grid is a rapid and simple method that can be effectively applied for the cryopreservation of human oocytes in ART program.