Evaluating the Role of First Polar Body Morphology on Rates of Fertilization and Embryo Development in ICSI Cycles

Abstract

Background: 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 performanceand pregnancy outcomes in an intracytoplasmic sperm injection (ICSI) program. According to somestudies, there is a correlation between oocyte performance and 1st PB morphology, while others havenot reported any correlation. The objective of this study is to evaluate the role of 1st PB morphologyon rates of fertilization and embryo development in ICSI cases.Materials and Methods: In this prospective study morphological characteristics of 470 metaphaseII (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 oocyteswere evaluated for 1st PB morphology. The oocytes were divided into two groups of A (normal 1stPB) 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, smoothendoplasmic reticulum cluster (SERc), debris in PVS, shape and dark oocyte were checked. Forverifying 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.Results: Twenty-seven percent of oocytes had fragmented 1st PB, while the remainder was associatedwith other morphological abnormalities. A total of 46.1% and 26.9% of oocytes showed double andmultiple defects, respectively. RF was the most common abnormality observed in group B. Nosignificant differences in women’s’ ages between groups A and B were noted (p=0.3). A total of 179and 107 oocytes (61.5% vs. 59.8%) were fertilized in groups A and B, respectively (p=0.7). Therates of good embryo formation for A and B groups were 66.5% and 55.6% (p=0.07), and cleavagerates were 77.7% and 68.5%, respectively (p=0.09).Conclusion: The data demonstrated that 1st PB morphology does not appear to be a prognosticfactor for rates of fertilization and embryo development in ICSI cycles.