The impact of examining the meiotic spindle by polarization microscopy on assisted reproduction outcomes.

To examine the effect of submitting oocytes to polarization microscopy (PM) before intracytoplasmic sperm injection (ICSI).Retrospective observational study.University hospital in Brazil.Couples undergoing ICSI.PM before ICSI (PM group) compared with no PM before ICSI (No-PM group)Fertilization and cleavage rates, formation of top-quality embryos (TQEs), and implantation, clinical pregnancy, miscarriage, and live-birth rates.The PM group consisted of 1,000 consecutive oocytes from 201 couples submitted to PM during the year of 2008. The No-PM group consisted of 1,400 oocytes from 249 couples: 700 consecutive oocytes were retrieved before we started using PM and 700 consecutive oocytes were retrieved after we stopped using PM. In the PM group, we observed an increased fertilization rate (79.7% vs. 72.5%, PM group vs. No-PM group, respectively) but reduced cleavage rate (86.2% vs. 92.5%) and TQE formation (33.1% vs. 49.9%). Implantation (18.7% vs. 20.6%), clinical pregnancy (31.8% vs. 33.3%), miscarriage (21.9% vs. 15.7%), and live-birth (24.9% vs. 28.1%) rates were not significantly different between groups.Use of PM was associated with increased fertilization rate but reduced cleavage rate and TQE formation; no significant difference was observed for implantation, clinical pregnancy, or live-birth rates.