Assessment of morphometric and morphological blastocyst parameters in relation to clinical outcomes in frozen single blastocyst transfer cycles: A retrospective study

Objective: This study compared the traditional blastocyst grading system with quantitative measurements of blastocyst expansion in relation to total pregnancy rate, implantation rate, and clinical pregnancy rate. Methods: A retrospective analysis was performed using data collected from patients undergoing frozen single embryo transfer cycles between 2021 and 2024. Single vitrified-warmed blastocyst transfers in self-patients were included, whereas cleavage-stage transfers and donor programs were excluded. All blastocysts were morphologically graded using the Gardner grading system. The degree of expansion was assessed morphometrically by measuring the inner diameter of the blastocyst from images obtained at the equatorial plane during embryo transfer, using Hamilton Thorne laser software. Multiple statistical tests were applied to analyze both qualitative and quantitative assessments of blastocysts in relation to clinical outcomes. Results: When comparing morphological parameters such as the quality of inner cell mass (ICM), trophectoderm (TE), and blastocyst expansion level, ICM and TE quality were found to significantly influence clinical outcomes. In comparing qualitative and quantitative (mean diameter) assessments of blastocysts with clinical outcomes, TE grade and blastocyst expansion level assessed qualitatively showed significant effects, whereas ICM quality and quantitative expansion measurements did not demonstrate statistical significance. Conclusion: Qualitative assessments of TE grade and blastocyst expansion level appear to be stronger predictors of clinical outcomes than ICM grade and morphometric assessment of blastocyst expansion. Larger datasets, including morphometric evaluation of ICM and TE cells, are recommended to clarify the predictive value of morphometric parameters.