Clinical validation of the early embryo viability assessment system: Analysis for the blastocyst morphology and pregnancy outcomes

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Objective: To determine the relationship between the early embryo viability assessment (EEVA) and blastocyst morphological parameters and pregnancy outcomes. Methods: This retrospective cohort study was conducted on 291 intracytoplasmic sperm injection cycles including 2 522 embryos with indications of prolonging embryo culture to the blastocyst stage in the Genea embryo review incubator, and 511 single vitrified- warmed blastocyst transfer cycles from January 2020 to June 2023. The EEVA system produced an EEVA score from E1 (best) to E5 (worse) for the potential of blastocyst formation. Blastocyst morphology was evaluated. The association between the EEVA score and each type of blastocyst morphology, implantation rate, clinical pregnancy, and ongoing pregnancy were assessed using generalized estimating equations. Results: The inner cell mass A (ICM A), trophectoderm A (TE A), blastocoele expansion degree of 3, 4, 5, 6, 7 rates were higher with lower the EEVA score. The adjusted odd ratio (aOR) (E5 vs E1) was 0.3 for ICM A, 0.174 for TE A and 0.210 for BL3, 4, 5, 6, 7 (all P<0.001), suggesting a significant association between lower EEVA scores and improved embryo quality. The implantation, clinical pregnancy, and ongoing pregnancy rate were also higher with lower the EEVA score. The aOR of E5 vs E1 was 0.245 for implantation, 0.185 for clinical pregnancy and 0.200 for ongoing pregnancy rate (P<0.001). Conclusions: There were associations between blastocyst morphology, pregnancy outcome and EEVA scores. The good blastocyst morphology and pregnancy outcomes are higher with lower the EEVA score.