A deep dive into the morphokinetics and ploidy of low-quality blastocysts

OBJECTIVE: To describe morphokinetic parameters and ploidy among low-quality blastocysts not meeting the criteria for clinical use. DESIGN: Prospective cohort study. SETTING: Academic medical center. PATIENT(S): Two hundred patients undergoing in vitro fertilization between February 2018 and November 2019. INTERVENTION(S): All embryos were cultured in a time-lapse incubator. All expanded blastocysts underwent preimplantation genetic testing for aneuploidy using next-generation sequencing. MAIN OUTCOME MEASURE(S): Static blastocyst morphology grading; morphokinetic parameters, including time to each cell division (2-cell formation to 8-cell formation); time to morula formation; time to the start of blastulation; time to blastocyst formation; and preimplantation genetic testing for aneuploidy results. RESULT(S): A total of 1,306 embryos progressed to the expanded blastocyst stage; of these, 935 embryos met the criteria for clinical use and were designated as high quality, whereas 371 embryos were graded as low quality and did not meet the criteria for use. In morphokinetic evaluation, low-quality embryos developed more quickly to 5-cell formation (t5) 48.4 [42.4–48.7) vs 50.2 [46.3–50.1] hours, but progressed more slowly thereafter with tM 91.5 [85.9–92.3] vs 88.3 [82.1–88.3] and tB 114.0 [106.4–113.9] vs 106.9 [101.3–107.4] hours. Among the low-quality embryos, 75.5% were aneuploid, 22.4% were euploid, and 2.2% had undetermined chromosome copy number results. Morphokinetic parameters did not differ between the euploid and aneuploid low-quality embryos. CONCLUSION(S): Morphokinetic analysis did not distinguish between euploid and aneuploid low-quality embryos.