Oocyte diameter as a predictor of fertilization and embryo quality in assisted reproduction cycles

ObjectiveTo assess the impact of the mean oocyte diameter (MOD) on occurrence of fertilization and embryo quality in assisted reproduction cycles.DesignProspective observational study.SettingSector of Human Reproduction of the University Hospital, Faculty of Medicine of Ribeirão Preto, University of São Paulo (HCFMRP-USP).Patient(s)Thirty-five women undergoing intracytoplasmic sperm injection (ICSI) at the University Hospital of Ribeirão Preto from May to October 2007.Intervention(s)MOD assessment.Main Outcome Measure(s)Occurrence of fertilization and qualitative embryo classification on 2nd and 3rd day after ICSI.Result(s)We divided 160 metaphase II oocytes according to MOD into groups A (MOD below the 25th percentile), B (MOD between 25th and 75th percentile), and C (MOD above the 75th percentile). There was no statistically significant association between MOD and the occurrence of fertilization or the qualitative embryo classification on days 2 and 3. There was no statistically significant difference between groups regarding number of cells or the qualitative embryo classification on days 2 and 3.Conclusion(s)The MOD of mature oocytes does not seem to be related to the occurrence of fertilization or to the developmental quality of human embryos on days 2 and 3 after ICSI.