Vitrification of human early cavitating and deflated expanded blastocysts: clinical outcome of 474 cycles.

PurposeThe present study was undertaken to evaluate and compare the post thaw survival, implantation and pregnancy rates of vitrified human early cavitating blastocysts with deflated expanded blastocysts.Material and methodsSupernumerary blastocysts were vitrified in 30% ethylene glycol-dimethyl sulphoxide based solution using cryoloop. Fully expanded blastocysts were deflated by gentle aspiration of the blastocoelic fluid using a micromanipulator until the cavity collapses prior to vitrification.ResultsOf the 576 vitrified blastocysts, 545 (94.61%) survived thawing in the early cavitating blastocyst group which was significantly higher than deflated expanded blastocyst group, in which only 370 survived thawing out of 459 (80.62%). However, no significant difference was observed in implantation and pregnancy rates between early cavitating and deflated expanded blastocyst groups.ConclusionsEarly cavitating blastocyst would be the ideal stage for cryopreservation of human blastocysts as it has higher survival rate and avoids additional invasive procedures like deflation of the blastocoele.