Maturation arrest of human oocytes as a cause of infertility: case report.

Maturation arrest of human oocytes may occur at various stages of the cell cycle. A total failure of human oocytes to complete meiosis is rarely observed during assisted conception cycles. We describe here a case series of infertile couples for whom all oocytes repeatedly failed to mature during IVF/ICSI. Eight couples, all presenting with unexplained infertility, underwent controlled ovarian stimulation followed by oocyte retrieval and IVF/ICSI. The oocytes were stripped of cumulus cells prior to the ICSI procedure and their maturity status was defined. In each couple, oocyte maturation was repeatedly arrested at the germinal vesicle (GV) (n = 1), metaphase I (MI) (n = 4) and metaphase II (MII) (n = 3) stage. Oocyte maturation arrest may be the cause of infertility in some couples previously classified as having unexplained infertility. The recognition of oocyte maturation arrest as a specific medical condition may contribute to the characterization of the yet poorly defined entity currently known as 'oocyte factor'. The cellular and genetic mechanisms causing oocyte maturation arrest should be the subject of further investigation.