Unequal pronuclear size - A powerful predictor of embryonic chromosome anomalies

Purpose: Our purpose was to evaluate whether pronuclei of unequal size, obs erved in 13.7% of zygotes evaluated after in vitro fertilization (IVF), are predictive of chromosome anomalies in the developing embryo. Methods: The ploidy of 38 embryos grown from zygotes with unequal-sized pro nuclei was assessed by fluorescent in situ hybridization (FISH). Twenty-six embryos developed after intracytoplasmic injection of sperm (ICSI) and 12 embryos were derived from conventional IVF: Results: Chromosome anomalies were documented in the ICSI and IVF groups in 88.5 and 50% of cases, respectively. Conclusions: We suggest that FISH should be employed to examine the ploidy of zygotes with unequal pronuclei, prior to embryo transfer.