Symmetry at the 4-Cell Stage Is Associated with Embryo Aneuploidy

Area of Science:

• Reproductive biology
• Embryology
• Genetics

Background:

• Preimplantation genetic testing for aneuploidy (PGT-A) is crucial for in vitro fertilization (IVF).
• Time-lapse imaging (TLI) offers non-invasive embryo assessment.
• Identifying reliable markers for aneuploidy beyond morphokinetics is essential.

Purpose of the Study:

• To investigate the association between quantitative morphometric parameters from TLI and embryo aneuploidy.
• To determine if specific morphometric measurements can predict aneuploidy.

Main Methods:

• Retrospective analysis of 182 embryos from 21 patients undergoing TLI and PGT-A.
• Morphokinetic analysis of cell division timing.
• Quantitative morphometric measurements including polar body distance, zona pellucida thickness, blastomere area, and 2-cell/4-cell stage symmetry.
• Receiver operating characteristic (ROC) curve analysis for aneuploidy prediction.

Main Results:

• While maternal age and blastocyst grade were associated with ploidy, 4-cell stage symmetry also showed a significant association (p=0.01).
• Euploid and aneuploid embryos exhibited similar morphokinetics and most morphometric parameters.
• An optimized ROC cutoff of 21% asymmetry at the 4-cell stage predicted high rates of aneuploidy.

Conclusions:

• Cleavage-stage morphometrics, particularly 4-cell stage symmetry, are valuable predictors of embryo aneuploidy.
• Embryo selection models utilizing TLI parameters can be enhanced by incorporating these quantitative morphometric measurements.
• This approach may improve IVF success rates by better identifying euploid embryos.