Clinical and Experimental Obstetrics & Gynecology (CEOG) is published by IMR Press from Volume 47 Issue 1 (2020). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with S.O.G.
Transfer of refrozen twice-thawed embryos do not decrease the implantation rate
Purpose: To assess the ability of twice frozen/thawed multi-cell embryos to implant in the human uterus. Method: Fourteen frozen embryo transfer (ET) cycles, in which at least one twice-frozen embryo was thawed for transfer, were matched to frozen ET cycles in which no twice-frozen embryos were thawed. The number of embryos thawed at the pronuclear stage and at the multi-cell stage were matched. Results: Multi-cell embryos frozen once had a 76.3% survival rate after thaw and those frozen twice had a 74.0% survival rate. For frozen ET cycles that had no twice-frozen embryos, the viable pregnancy and implantation rates were 58.3% and 29.8%, respectively. The corresponding rates for cycles involving at least one twice-frozen embryo were 50.0% and 25.5%, respectively. Conclusion: The inclusion of twice-frozen embryos in the embryo pool did not reduce the implantation rate.