Oocyte donation: not all oocyte cryobanks are the same

Is the efficacy of imported vitrified oocyte donation affected by the cryobank of origin?

Longitudinal cohort study, including 249 completed oocyte warming cycles from 200 recipients (January 2016-July 2020). No severe male factor was included. Vitrified oocytes were provided by three Spanish cryobanks. Primary outcome was cumulative live birth delivery rate (CLBR) per completed oocyte warming cycle.

After warming 1535 oocytes, 1244 survived (81.0%) and 945 fertilized (76.0%); embryo utilization rate was 65.3%. The overall CLBR per completed cycle was 47.0% but was lower in cryobank 1 (31.2%) versus cryobank 2 (56.0%, P = 0.0010) and cryobank 3 (50.8%, P = 0.0241). Multivariate logistic regression analysis identified survival of four or more oocytes as the strongest predictor for delivery (P = 0.0282). Only 202 out of 249 oocyte warming cycles had four or more survived oocytes in a proportion that was significantly lower in cryobank 1 versus cryobank 2 (70.1% versus 89.0%, P = 0.0020); comparison with cryobank 3 (81.0%) was not significant. In the 202 oocyte warming cycles, CLBR in cryobank 1 (37.0%) was lower versus cryobank 2 (58.8%, P = 0.0115) and cryobank 3 (60.8%, P = 0.0019), suggesting a reduced viability in oocytes from cryobank 1 that survived warming.

Differences were found in the efficacy of imported vitrified oocytes in relation to the cryobank of origin. Each centre needs to evaluate the results internally when starting a collaboration with an oocyte cryobank to establish the necessary measures to maximize treatment efficacy.