Survival Rates in Closed and Open Vitrification for Human Mature Oocyte Cryopreservation: A Meta-Analysis

Survival of warmed oocytes is the first part and is one of the most important aspects of in vitro fertilization following oocyte cryopreservation. There is no definite conclusion about the difference in survival rates between closed and open vitrification for oocyte cryopreservation. This study aimed to investigate whether there is a difference in survival rates between closed and open vitrification for cryopreservation of human mature oocytes.

A literature search was performed using the MEDLINE, Cochrane Central Register of Controlled Trials, and Embase databases. A total of 4 studies were included in the meta-analysis.

In the frequentist meta-analysis, the random effects model showed no statistically significant difference in survival rates between closed and open vitrification (risk ratio [RR] 0.8873, 95% confidence interval [CI] 0.7658-1.0280). However, an effect size deviation of the RR from 1.0 and a borderline trend of the 95% CI were noted. In the Bayesian meta-analysis, the posterior probability that closed vitrification would decrease the survival rate when compared to that with open vitrification was 83.04% for the random effects model.

It is not yet possible to conclude that closed vitrification is an aseptic alternative to open vitrification in human mature oocyte cryopreservation.