Efficacy of ovarian tissue cryopreservation for fertility preservation: lessons learned from 545 cases.

STUDY QUESTION: How effective is ovarian tissue cryopreservation (OTC)?

SUMMARY ANSWER: In our cohort of patients who underwent OTC, premature ovarian failure (POF) rates, return rates and pregnancy rates after autotransplantation were 31.5, 4.4 and 33%, respectively.

WHAT IS KNOWN ALREADY: OTC for fertility purposes has been performed for >20 years now. With over 86 live births reported worldwide and success rates of ~30% after autotransplantation of frozen-thawed ovarian cortex, the procedure should no longer be considered experimental. However, very few publications report the efficacy of this procedure.

STUDY DESIGN, SIZE, DURATION: Cases of ovarian tissue cryobanking for fertility preservation performed between 1997 and 2013 in a single institution were reviewed by analysis of the cryobank database and a prospective questionnaire sent out in March 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS: There were 545 patients who underwent OTC during this period. The analysis included indications for OTC, survival rates, ovarian function and spontaneous pregnancies after OTC, come-back rates for ovarian tissue transplantation, pregnancy rates after transplantation, and complication and satisfaction rates.

MAIN RESULTS AND THE ROLE OF CHANCE: OTC was performed in this cohort at a mean age of 22.3 ± 8.8 years for oncological indications (79%), benign gynecological pathologies (17.5%) and genetic risks of POF (3.5%). Of the 545 patients, 29% were under 18 years of age at the time of OTC and 15% were prepubertal. While 10% of patients died from their disease, 21 patients (3.9%) underwent autotransplantation, 7 of whom delivered a healthy baby, yielding a post-transplantation live birth rate of 33%. Of 451 patients who were sent the questionnaire, 143 agreed to respond (32%). Nevertheless, ovarian function could not be evaluated in 36% of those who answered. Of 92 evaluable patients, 31.5% were menopausal and 68.5% showed persistent ovarian function. Of 52 women who attempted to conceive naturally, 37 were successful (71%). Among 140 patients who answered the questionnaire, 96% were satisfied with the procedure and only 1 major complication (intra-abdominal hemorrhage) was encountered. Among all the patients, 12% have donated their ovarian cortex for research purposes or have had it destroyed.

LIMITATIONS, REASONS FOR CAUTION: The questionnaire participation rate (32%), limited follow-up (mean 7.6 ± 3.5 years) and use of only clinical criteria for evaluation of ovarian function made it difficult to accurately assess the risk of POF and efficiency of OTC.

WIDER IMPLICATIONS OF THE FINDINGS: Our findings confirm a 30% pregnancy rate after ovarian cortex autotransplantation but also stress the difficulties of evaluating the real efficacy of OTC.

STUDY FUNDING/COMPETING INTEREST(S): No funding was sought for this study and none of the authors have any conflict of interest.

TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registration ID: CRYOFONOV01.