Spindle observation aids decision-making for early rescue ICSI.

Abstract

Objective: To investigate whether spindle visualization using polarized light microscopy (PLM) can assist in identifying unfertilized oocytes prior to early rescue intracytoplasmic sperm injection (R-ICSI).

Methods: This retrospective cohort study included 356 early R-ICSI cycles, of which 24 were excluded from the analysis. The remaining 332 cycles were divided into study group and control group based on whether spindle observation had been performed before early R-ICSI. The fertilization rate, embryo development, and clinical outcome were compared between the two groups.

Results: Of the 356 participants included, 332 completed follow-up analysis. The study group demonstrated a significantly higher normal fertilization rate (82.55% vs. 71.49%, P < 0.01) and a lower 3PN rate (3.17% vs. 8.89%, P < 0.01) after following R-ICSI. For oocytes without visible spindles in the study group or those with fragmented polar bodies in the control group, in vitro fertilization (IVF) was performed, resulting in a higher normal fertilization rate in the study group (53.37% vs. 36.43%, P < 0.01). However, there was no significant difference between the two groups in terms of embryo development and implantation potential. In the high-age subgroup (over 35 years old), the normal cleavage rate was significantly higher in the spindle examination group compared to the non-observation group (38.60% vs. 22.47%, P < 0.05).

Conclusion: Utilizing PLM for spindle observation can effectively identify oocytes suitable for early R-ICSI to improve fertilization outcomes and optimize embryo development in women over 35 years old.