Embryo evaluation by analysing blastomere nuclei

Area of Science:

• Reproductive biology
• Embryology
• In vitro fertilization (IVF)

Background:

• Developing improved embryo selection standards is crucial for enhancing IVF success rates.
• Conventional methods rely on morphological evaluation, which has limitations in predicting implantation potential.
• A novel approach combining morphological assessment with blastomere nuclei analysis was developed.

Purpose of the Study:

• To evaluate a new embryo grading system that integrates conventional morphological assessment with blastomere nuclei analysis.
• To determine if nuclei counting method offers superior prediction of implantation rates compared to conventional methods.
• To refine embryo selection criteria for improved IVF outcomes.

Main Methods:

• Retrospective analysis of 744 embryos from 459 IVF cycles, including day 2 and blastocyst transfers.
• Embryo evaluation involved conventional morphological assessment (blastomere size, fragmentation) and nuclei counting (multinucleation, anucleation).
• Implantation rates were examined for each transferred embryo and blastocyst based on the grading methods.

Main Results:

• The nuclei counting method demonstrated a better prediction of implantation rates than the conventional method.
• Embryos classified as high quality by conventional but low quality by nuclei counting had a significantly lower implantation rate (6.3%).
• For blastocyst transfers, high-quality embryos identified by nuclei counting had the highest implantation rate (25.5%), while low-quality ones rarely implanted (3.2%).

Conclusions:

• Normality of blastomere nuclei is a more critical indicator of embryo quality than fragmentation or blastomere uniformity.
• When nucleic status is similar, embryos with less fragmentation should be prioritized.
• For blastocyst transfers, selecting embryos with normal nuclei on day 2 is recommended for day 5 transfer.