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

Objective: Clinical application of vitrification for the cryopreservation o f 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 s equential media and subsequent vitrification of supernumerary blastocysts u sing a cryoloop technique. Main Outcome Measure(s): Clinical outcome after transfer of vitrified blast ocysts. 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 preg nancies were achieved after 19 transfers. One healthy baby was born, four p regnancies are ongoing, and one ended in miscarriage. Conclusion(s): Human blastocysts can be Successfully vitrified by suspensio n on a small nylon loop and a direct plunge into liquid nitrogen. A deliver y and ongoing pregnancies prove the safety of this method. This report docu ments the first successful pregnancy and delivery achieved by blastocyst vi trification using the cryoloop containerless technique. (Fertil Steril(R) 2 001;76:618-20. (C) 2001 by American Society for Reproductive Medicine).