Blastocyst cryopreservation using solid surface vitrification: A preliminary study

OBJECTIVE: The objective was to evaluate the effectiveness of a blastocyst cryopreservation program using solid surface vitrification. SETTING: This study took place in a university teaching hospital. STUDY DESIGN: Retrospective observational study. MATERIALS AND METHODS: Women undergoing frozen embryo transfer cycles over a 4-year period between 2006 and 2010 were studied. The cryopreservation policy followed was a vitrification protocol performed at the blastocyst stage, using a solid surface (nonimmersion) method. The post-thaw survival rate, implantation rate, clinical pregnancy rate, live birth rate, and neonatal outcome were recorded. RESULTS: Eighty-one women underwent 86 frozen embryo transfer cycles. Of the 240 blastocysts warmed, 204 survived giving a cryosurvival rate of 85% (204/240). The clinical pregnancy, implantation, miscarriage, ongoing pregnancy, and live birth rates per transfer were 47%, 29%, 12%, 16%, and 23% respectively. Of the 20 live births, there were 16 singletons and 4 twins. Eleven boys and 13 girls were delivered with no major or minor abnormality detected. CONCLUSION(S): The blastocyst vitrification protocol using the solid surface method is effective with results comparable to fresh blastocyst transfers. While retaining the rapid cooling effect, the nonimmersion technique eliminates the risk of contamination and disease transmission. Larger studies with long-term follow-up data would further confirm the efficacy and safety of this method of vitrification.