Comparison of the quality of ovarian tissue cryopreservation by conventional slow cryopreservation and vitrification-a systematic review and meta-analysis

BackgroundOvarian tissue cryopreservation is increasingly applied in patients undergoing gonadotoxic radiotherapy or chemotherapy treatment or other patients who need to preserve their fertility. However, there is currently limited evidence to know which type of ovarian tissue cryopreservation is better. The advantages and disadvantages of conventional slow cryopreservation and vitrification are still controversial. The purpose of this meta-analysis was to analyze the ovarian tissue quality of ovarian tissue cryopreservation by conventional slow cryopreservation and vitrification.MethodsAccording to the keywords, Pubmed, Embase, and Cochrane Library were searched for studies to January 2024. Studies comparing the follicular viability of conventional slow cryopreservation versus vitrification were assessed for eligibility. The meta-analysis was performed using Stata software (Version 12.0) and Review Manager (Version 5.2).ResultsA total of 18 studies were included in this meta-analysis. The pooled results of the primary outcomes indicated that there was no difference between the two approaches for follicular viability (RR = 0.96, 95% CI: 0.84-1.09, P = 0.520, I2 = 95.8%, Random-effect), the proportion of intact primordial follicles (RR = 1.01, 95% CI: 0.94-1.09, P = 0.778, I2 = 70.6%, Random-effect). The pooled results of the secondary outcomes indicated that there was no difference between the two approaches for the proportion of DNA fragmented follicles (RR = 1.20, 95% CI: 0.94-1.54, P = 0.151, I2 = 0.0%, Fixed-effect), and the proportion of stromal cells (RR = 0.58, 95% CI: 0.20-1.65, P = 0.303, I2 = 99.7%, Random-effect).ConclusionsConventional slow cryopreservation and vitrification appear to provide comparable outcomes. The heterogeneity of the literature prevents us from comparing these two techniques. Further high-quality studies are needed to enhance this statement. This meta-analysis provides limited data which may help clinicians when counselling patients.