Efficacy of oocyte vitrification combined with blastocyst stage transfer in an egg donation program

Abstract

BACKGROUND A successful oocyte vitrification program is important for women with various indications for assisted reproduction technology. The objective of this study was to report the outcome of vitrification of oocytes, obtained through an oocyte donation program, by evaluating the embryo development, pregnancy and implantation rates (IRs) after blastocyst transfer. METHODS A total of 1098 oocytes were obtained from 78 donors. There were 312 oocytes used in the study group (vitrified oocytes) and 786 used in the control group (fresh oocytes). There were 34 recipients who received blastocysts obtained from vitrified oocytes and 58 recipients who received blastocysts from fresh oocytes. The fertilization rate, cleavage rate, embryo quality, pregnancy rate (PR) and IR were compared between groups. RESULTS Vitrified oocytes showed a survival rate of 89.4%. There was no difference in the fertilization rate (76.1 and 87.5%), Day 2 cleavage rate (96.3 and 98.0%) or blastocyst formation rate (41.3 and 45.3%) for the study and control groups, respectively. PRs, IRs and miscarriages rates (MRs) were similar for the study group compared with the control group (PR: 61.8 versus 60.0%; IR: 43.9 versus 42.9%; MR: 9.5 versus 5.9%). CONCLUSIONS The developmental competence of embryos obtained from vitrified oocytes is not affected by the vitrification procedure, since they preserve the potential to be fertilized and to develop into high-quality blastocysts, similar to embryos from fresh oocytes. The successful clinical outcome indicates the use of this procedure for oocyte donation programs and for oocyte storage in general.

Closed vitrification of human oocytes and blastocysts: outcomes from a series of clinical cases

“…Oocyte survival using the closed Rapid-i tool was similar to reports for open systems using the same cryoprotectants [4,[29][30][31][32][33][34]. Limited previous experience with a variety of closed systems (not Rapid-i) has generated survival rates ranging from 60 to 90 % [18,24,35,36].…”

Oncofertility in Canada: cryopreservation and alternative options for future parenthood

“…Cobo et al 22 randomized 600 patients to receive either fresh donor oocytes or frozen oocytes post vitrification and found no difference in the pregnancy rate per transfer (55.4% vs. 55.6%) or ongoing pregnancy rate per transfer (49.1% vs. 48.3%). Those results have been replicated in multiple other retrospective studies [23][24][25] . Other authors have also commented on the lack of differences noted in embryo quality between fresh and frozen oocytes from the same donor 26,27 .…”

Effect of vitrification procedure on chromosomal status of embryos achieved from vitrified and fresh oocytes

“…Since the first pregnancy achieved with a vitrified/warmed human oocyte [83] and the first birth of a healthy baby [84], vitrification results have improved significantly during the last decade [17][18][19][20][21][22][23][24][25][26][85][86][87][88]. Vitrification is the glass-like solidification of a solution at low temperature, without ice crystal formation.…”

“…Unlike slow freezing, vitrification results in the total elimination of ice crystal formation, within the cells being vitrified and outside the cells in the surrounding solution [78]. Oocyte vitrification avoids meiotic spindle damage and has resulted in survival rates of over 80% [19][20][21]23,48,90]. Additionally, pronuclear zygotes [91], cleavage-stage embryos [82], and blastocysts [92][93][94] have been successfully vitrified.…”

“…As an alternative to slow freezing, the vitrification procedure has been recently applied for human oocytes and embryos [15,16] allowing to improve the percentages of oocyte survival, fertilization, embryo development rates and clinical outcomes [17][18][19][20][21][22][23][24][25][26]. Vitrification is a non-equilibrium method and may be regarded as a radical approach in which ice crystal formation is totally eliminated.…”