Background: In vitro fertilization (IVF) data suggest improved live birth rates for embryos transferred at the blastocyst versus the cleavage stage. Embryos that have not reached the blastocyst stage by day 5 postthaw have diminished potential for implantation and live birth. Few data exist regarding embryogenesis and optimal timing of transfer for embryos derived from previously cryopreserved oocytes, but we report the case of 100% implantation following transfer of 3 developmentally-delayed embryos derived from cryopreserved oocytes.
Case: A 38-year-old woman cryopreserved 20 oocytes for the purpose of future childbearing. At age 42 she returned to thaw and fertilize 8 oocytes using donor sperm. Embryos were cultured to day 5 postthaw, at which time 1 morula and 2 cleavage-stage embryos were available for transfer. Three-embryo transfer resulted in a heterotopic tubal pregnancy and twin intrauterine gestation. Laparoscopic salpingectomy was performed for the ectopic gestation. The twin intrauterine pregnancy spontaneously reduced to singleton, and the patient delivered a live-born infant.
Conclusion: While heterotopic and multifetal pregnancy are known risks of multiembryo transfer, 3 lesser-quality embryos derived from cryopreserved oocytes would be unlikely to have high implantation potential. Future studies are needed to delineate timing of embryogenesis events in previously cryopreserved oocytes.