Multinucleation of a sibling blastomere on day 2 suggests unsuitability for embryo transfer in IVF-preimplantation genetic screening cycles

Objective: To evaluate the impact of multinucleation of a sibling blastomere of day 2 embryos on the rate of aneuploidy detected by day 3 preimplantation genetic screening (PGS) biopsy and the effect on subsequent implantation and pregnancy rates. Design: Retrospective cohort study. Setting: University-based IVF center. Patient(s): A total of 141 couples undergoing their first IVF-PGS cycle for idiopathic recurrent pregnancy loss (RPL) or multiple failed IVF implantations. Intervention(s): Biopsy of single-nucleated blastomeres for PGS analysis of chromosomes X, Y, 13, 15, 16, 17, 18, 21, and 22 by fluorescence in situ hybridization. Main Outcome Measure(s): Aneuploidy, implantation, and pregnancy rates. Result(s): PGS revealed an increased incidence of aneuploidy when comparing multinucleated day 2 embryos with single-nucleated embryos (85% vs. 78%; relative risk 0.92 (95% confidence interval 0.84-1.00). Transfer of single-nucleated euploid embryos resulted in clinical pregnancy and implantation rates of 28% and 24%. Transfer of multinucleated euploid embryos resulted in no implantations. Conclusion(s): The presence of multinucleated blastomeres on day 2 of embryo development, 1 day before biopsy, predicts an increase of aneuploidy and poor pregnancy outcomes in IVF-PGS cycles.