Time-lapse analysis of embryos classified as euploid, mosaic, and aneuploid after embryonic trophectoderm biopsy.

PURPOSE

Analyze morphokinetic, morphology, and KIDscore™Day5 in different PGT-A classes, focusing on putative mosaicism level and type.

METHODS

The single-center retrospective study analyzed 832 embryoscope-cultured blastocysts from cycles with at least one putative mosaic, conducted from 2020 to 2022. A P-value < 0.05 was considered statistically significant.

RESULTS

Putative mosaic embryos were significantly delayed compared to euploid in tPNF, t2, t4, t7, and t8 but significantly faster than aneuploid in tPNF, t2, t3, t4, t5, tSC, tM, tSB, and tB. Regarding the level, low-putative mosaic embryos (< 50%) showed significantly earlier tSC, tM, tSB, and tB compared to aneuploid, whereas high-putative mosaic embryos exhibited significantly earlier tSB and tB. Concerning the type of putative mosaicism, segmental aneuploidies reached significantly earlier t8, tM, and tB than complex aneuploidies. The study also investigated the usefulness of KIDscore™Day5 for embryo selection as an additional tool to PGT-A. A significant decrease in KIDscore™Day5 was observed from euploid to low-putative mosaic, from high-putative mosaic to aneuploid, and between segmental and complex-putative mosaic. The observed differences in KIDscore™Day5 were partially confirmed by transfer results: euploid blastocysts showed the most favorable clinical outcomes compared to low- and high-putative mosaics. Additionally, both euploid and segmental putative mosaic embryos exhibited the best clinical results compared to whole chromosome and complex putative mosaic. Moreover, within the same PGT-A class, embryos with the lowest KIDscore™Day5 values had significantly lower clinical results.

CONCLUSIONS

The data highlight that morphology, morphokinetics, and chromosome content in trophectoderm biopsy are closely related, and the KIDscore™Day5 algorithm reflects this interplay.