Evaluating the role of first polar body morphology on rates of fertilization and embryo development in ICSI cycles

ABSTRACT

Recent studies have demonstrated that morphology of the first polar body [1st PB] is related to oocyte viability, which can be used as a prognostic tool to predict oocyte performance and pregnancy outcomes in an intracytoplasmic sperm injection [ICSI] program. According to some studies, there is a correlation between oocyte performance and 1st PB morphology, while others have not reported any correlation. The objective of this study is to evaluate the role of 1st PB morphology on rates of fertilization and embryo development in ICSI cases. In this prospective study morphological characteristics of 470 metaphase II [MII] oocytes were assessed in 80 ICSI cycles. The women were ages 21-42 years [mean 32.6 +/- 0.2]. Their oocytes were retrieved after a hyperstimulation protocol. After denudation, all oocytes were evaluated for 1st PB morphology. The oocytes were divided into two groups of A [normal 1st PB] and B [abnormal fragmented 1st PB]. In addition, other abnormalities, such as refractile bodies [RF], wide previtelline space [wPVS], central and general granulation, bull's eye, vacuole, smooth endoplasmic reticulum cluster [SERc], debris in PVS, shape and dark oocyte were checked. For verifying of fertilization, about 18-19 hours post-ICSI, oocytes were checked for two-pronuclear. Assessments of embryo quality, development and embryo transfer were done at day two. Chisquare, Fisher's exact and independent sample t tests were chosen for statistical analysis. Twenty-seven percent of oocytes had fragmented 1st PB, while the remainder was associated with other morphological abnormalities. A total of 46.1% and 26.9% of oocytes showed double and multiple defects, respectively. RF was the most common abnormality observed in group B. No significant differences in women's' ages between groups A and B were noted [p=0.3]. A total of 179 and 107 oocytes [61.5% vs. 59.8%] were fertilized in groups A and B, respectively [p=0.7]. The rates of good embryo formation for A and B groups were 66. 5% and 55. 6% [p=0.07], and cleavage rates were 77. 7% and 68.5%, respectively [p=0.09]. The data demonstrated that 1st PB morphology does not appear to be a prognostic factor for rates of fertilization and embryo development in ICSI cycles