Relative Position of the Meiotic Spindle and Polar Body as a Marker of Oocyte Maturation Improves the Utilization and Pregnancy Rates

Abstract This research demonstrates how a mutual position of the human oocytes meiotic spindle (MS) and the first polar body (PB) correlates with the probability of obtaining high-quality embryos (utilization rates) and high pregnancy rates after intracytoplasmic sperm injection (ICSI). The quality of optically birefringent MS and the angle (α) between MS and PB (evaluated using polarizing microscopy), were used to indicate oocyte maturation and appropriate time for fertilization. In this study, 124 patients undergoing in vitro fertilization (IVF) whose oocytes were evaluated by MS visualization had a significantly higher clinical pregnancy rate (38% vs 26%) and utilization rate (54% vs 38%) when compared to the control group, using one standard IVF cycle without MS visualization. Significantly, in group of 79 patients > 35 years old, 34% became pregnant when α was evaluated and ICSI time adjusted to achieve the full oocyte maturation, compared to only 18% in the control group. The number of high-quality embryos in the MS visualized group was significantly higher compared to the control group, increasing the probability of pregnancy. Based on this research, we propose to incorporate monitoring the mutual position of MS and PB as a valid marker of embryo quality which can significantly improve pregnancy rate.