Successful birth after transfer of vitrified human blastocysts with use of a cryoloop containerless technique

Objective: Clinical application of vitrification for the cryopreservation of human blastocysts. Design: Clinical trial of vitrification of human blastocysts. Setting: Private assisted reproductive technology clinic. Patient(s): Supernumerary blastocysts after fresh blastocyst transfer were vitrified for subsequent transfer. Intervention(s): Culture of pronuclear embryos to the blastocyst stage in sequential media and subsequent vitrification of supernumerary blastocysts using a cryoloop technique. Main Outcome Measure(s): Clinical outcome after transfer of vitrified blastocysts. Result(s): A total of 60 vitrified blastocysts from 21 patients were warmed, and the survival rate at 2 hours after warming was 63%. Six clinical pregnancies were achieved after 19 transfers. One healthy baby was born, four pregnancies are ongoing, and one ended in miscarriage. Conclusion(s): Human blastocysts can be Successfully vitrified by suspension on a small nylon loop and a direct plunge into liquid nitrogen. A delivery and ongoing pregnancies prove the safety of this method. This report documents the first successful pregnancy and delivery achieved by blastocyst vitrification using the cryoloop containerless technique. (Fertil Steril(R) 2001;76:618-20. (C) 2001 by American Society for Reproductive Medicine).