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.