A new day 4 embryo evaluation system to predict the formation of transferable blastocyst

Abstract

Purpose To explore a day 4 embryo evaluation system based on the potential for the embryo to develop into a transferable blastocyst. Methods We observed the outcome of blastocyst culture for 1235 embryos from 199 patients. We considered the developmental stage, fragmentation, whether it was in a stage-specific cleavage pattern, and normal fertilization to formulate scoring criteria, based on whether they developed into transferable blastocysts. The receiver operative characteristics(ROC) curve was used to compare the predictive abilities of four criteria for day 4 evaluation to develop into transferable blastocysts and high-quality blastocysts. Results The developmental stage, fragmentation, normal fertilization and stage-specific cleavage pattern had the greatest impact on the formation of transferable blastocysts. There were significant differences in the formation rates of transferable blastocysts and high-quality blastocysts among different embryo grades. The areas under ROC curves of the day 4 embryo evaluation criteria constructed in this study was the highest in predicting transferable blastocyst formation, relative to the other three evaluation criteria. Conclusion This study observed the presence of pseudo-compacted embryos similar to cleavage-stage embryos. The Day 4 embryo evaluation criteria constructed in this study can effectively predict the formation of transferable blastocysts.