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.