Impact of embryo quality in fresh versus vitrified oocytes in an egg donation program

Abstract

OBJECTIVE: The objective of this study was to compare the embryo quality and gestational results in an egg donation program using fresh and vitrified/thawed oocytes, previously stored in an oocyte bank. DESIGN: Retrospective, comparative, observational and transversal study. MATERIALS AND METHODS: A total of 43 patients who underwent 49 embryo transfers from January 1st to December 31st 2009 were analyzed. Group I involved 27 patients whose treatment was carried out using fresh oocytes, while group II involved 16 patients using vitrified/thawed oocytes by Cryotop method. Endometrial preparation consisted of increasing doses of estradiol valerate and micronized progesterone. Recipients with ovarian function were down-regulated with GnRH agonist in the lutheal phase of the previous cycle. Donor stimulation was performed with recombinant FSH (starting dose from 150 to 300 UI/day, according to antral follicle account) and GnRH antagonist. RESULTS: Mean age of the patients was 41 ± 4,0 (group I) and 42,06 ± 2,9 (group II). Survival rate of vitrified oocytes was 86,6%. Fertilization rate after ICSI was 75,7% and 67,0%, respectively. Embryo development was similar in both groups, as well as top quality embryo (29,2% and 31,9% respectively). Pregnancy and implantation rates were 47,1% and 24,02% in group I; 46,7% and 28,8% in group II. There were no statistically significant differences in none of the outcomes analyzed. CONCLUSION: Vitrification preserves oocyte potential to fertilize and further development. Our results show that oocyte vitrification procedure is equal to fresh egg donation with regard to embryo development and gestational results. This technique provides an excellent tool to establish an oocyte bank which in turn optimizes egg donation programs.