Treatment with gonadotropin-releasing hormone (GnRH) antagonists in women suppressed with GnRH agonist may avoid cycle cancellation in patients at risk for ovarian hyperstimulation syndrome.

Forty-seven patients at high risk for ovarian hyperstimulation syndrome because of markedly elevated serum E2 levels on either long-luteal or microdose flare leuprolide acetate regimens were treated with ganirelix acetate. Despite being pretreated with GnRH agonist and without withholding gonadotropins, serum E2 decreased by 49.5% and 41.0% of pretreatment values (long luteal and microdose flare, respectively) after initiation of ganirelix, and 68.1% of the patients became pregnant.