Use of metaphase I oocytes matured in vitro is associated with embryo multinucleation

Objective: To evaluate the impact of oocyte maturational stage at retrieval on embryo multinucleation. Design: Retrospective study. Setting: Private institution for assisted reproduction. Patient(s): A total of 412 patients undergoing 500 intracytoplasmic sperm injection (ICSI) cycles between August 2006 and September 2010. Intervention(s): Routine ICSI laboratory procedures. Main Outcome Measure(s): Normal and abnormal fertilization; embryo development; arrest at pronuclear stage; failure to undergo first mitotic division; presence of embryo multinucleation; embryo quality; pregnancy, implantation, and miscarriage rates. Result(s): A significantly lower percentage of multinucleation was found in embryos originating from metaphase II (MII) oocytes when compared with MI-II- and MI-derived oocytes. Significantly fewer multinucleated cells per embryo were observed in MII-derived oocytes. Clinical pregnancy and implantation rates were significantly higher when only embryos derived from MII oocytes were transferred. Conclusion(s): Embryo multinucleation rate increases when in vitro-matured (2-5 hours incubation) MI (MI-II) oocytes are used instead of in vivo-matured oocytes in ICSI. Furthermore, all other ICSI outcome parameters are also compromised. The use of donated gametes does not modify these results. (Fertil Steril (R) 2013; 99: 414-21. (C) 2013 by American Society for Reproductive Medicine.)