Comparison of vitrification and conventional slow freezing for cryopreservation of ovarian tissue with respect to the number of intact primordial follicles: A meta-analysis. Issue 39 (September 2016)

• Record Type: Journal Article
• Authors: Zhou, Xin-Hui; Zhang, Dan; Shi, Jin; Wu, Yi-Jun
• Editors: Omboni., Stefano
• Is Part Of: Medicine. Volume 95:Issue 39(2016)
• Page Start: e4095
• Publication Date: 2016-09
• Subjects: cryopreservation -- follicle -- freezing -- ovary -- vitrification; Medicine -- Periodicals; Medicine -- Periodicals; Médecine -- Périodiques; Geneeskunde; Medicine; Periodicals; Periodicals; 610.5
• DOI: 10.1097/MD.0000000000004095
• Languages: English
• ISSNs: 0025-7974

Abstract

Abstract: Background: Vitrification is the standard method for cryopreserving human oocytes and embryos, but its effects on ovarian tissue are uncertain. The purpose of this meta-analysis was to compare the proportion of intact primordial follicles in ovarian tissue cryopreserved with vitrification versus slow freezing. Methods: Medline, Cochrane, EMBASE, and Google Scholar databases were searched until November 11, 2014 using combinations of the search terms: ovarian tissue, cryopreservation, vitrification, follicle, follicles. Inclusion criteria were randomized controlled trails, two-arm prospective studies, and retrospective studies in which ovarian tissues were preserved by vitrification or conventional slow freezing. The primary outcome was the proportion of intact primordial follicles. Results: Six studies were included in the meta-analysis. The number of patients ranged from 3 to 20, and age ranged from 20 to 43 years. Total number of morphologically intact follicles ranged from 14 to 2058, among which 6 to 724 were primordial. The pooled odds ratio (OR) showed no significant difference in the proportion of intact primordial follicles after slow freezing or vitrification (OR = 1.228, 95% confidence interval [CI]: 0.769–1.961, P = 0.390). Sensitivity analysis using the leave-one-out approach indicated no considerable changes in the direction and magnitude of the pooled estimates when individual studies were excluded one at a time, indicating good reliability of the current analysis. Conclusions: Vitrification and slow freezing produce equivalent results with respect to intact primordial follicles for the cryopreservation of human ovarian tissue. However, the included studies varied in the cryopreservation protocols used.