Birth of a healthy baby following vitrification of human blastocysts

Objective: To assess vitrification of human blastocysts. Design: Retrospective study of blastocyst vitrification. Setting: A private clinic. Patient(s): Twenty couples with different types of infertility. Intervention(s): Blastocysts were frozen with rapid vitrification and then transferred after thawing. We vitrified blastocysts using a modification of Ishimori’s vitrification solution of ethylene glycol and dimethyl sulfoxide (VSED). Main Outcome Measure(s): After thawing, survival was defined by the embryo’s development morphology after 6 hours or overnight culture. Result(s): Eighteen of 20 patients underwent treatment. Of 45 vitrified blastocysts, 36 survived, for a survival rate of 80% (36 of 45). The implantation rate was 21.9% (7 of 32), and the pregnancy rate (per embryo transfer cycle) was 33.3% (6 of 18). One of the pregnancies resulted in the delivery of a healthy baby. Conclusion(s): Supernumerary embryos were grown in culture to blastocysts, and the survival rate of vitrified-thawed blastocysts was the same as that for slow freezing of early stage embryos. Blastocyst vitrification should prove effective for clinical treatment. The present results strongly suggest that this rapid and successful vitrification procedure will replace conventional cryopreservation in the future.