Vitrification of human blastocysts using the cryoloop method: successful clinical application and birth of offspring.

PURPOSE: The purpose was to investigate vitrification of human blastocysts using the cryoloop. METHODS: Thirteen couples elected to have blastocysts cryopreserved via vitrification (N = 54 blastocysts). Embryos were exposed to two vitrification solutions, pipetted onto the cryoloop then plunged into liquid nitrogen. On the day of embryo replacement, blastocysts were warmed by passage through three dilution media, and rinsed into culture medium. RESULTS: Four couples returned for cryopreserved embryo replacement. Fifteen blastocysts were warmed; all 15 (15/15; 100%) were recovered. Fifteen (15/15; 100%) blastocysts were deemed viable, and 13 were replaced. Two replacements did not result in pregnancy; one resulted in clinical pregnancy with a blighted ovum; one resulted in clinical pregnancy with the live, term birth of a healthy male infant. Two of 13 embryos implanted yielding an implantation rate of 15.4%. CONCLUSIONS: These preliminary data suggest that blastocysts can be successfully vitrified using the cryoloop method.