Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of ovulation induction and is a life threatening iatrogenic complication. In patients with GnRH agonist protocol, both withdrawing GnRH agonist and GnRH antagonist administration are associated with a reduction in (E2) levels with subsequent decreasing the incidence and severity of OHSS. This work is to compare the clinical and endocrine outcome response of cycles in which GnRH agonist withdrawing with cycles in which the GnRH antagonist administration in patients at risk of severe OHSS.

Background: Elevated estradiol (E2) levels and multiple folliculogenesis predispose to development of ovarian hyperstimulation syndrome (OHSS). In patients with GnRH agonist protocol, both withdrawing GnRH agonist and GnRH antagonist administration are associated with a reduction in (E2) levels with subsequent decreasing the incidence and severity of OHSS. This work is to compare the clinical and endocrine outcome response of cycles in which GnRH agonist withdrawing with cycles in which the GnRH antagonist administration in patients at risk of severe OHSS.

Purpose: To compare the decreased levels of estradiol (E2), coasting days, severity of OHSS and pregnancy outcomes of cycles in which GnRH agonist withdrawing with cycles in which the GnRH antagonist administration in patients at risk of severe OHSS.

Methods: a prospective randomized study was designed to evaluate clinical and endocrine outcome in two different coasting protocols. Women (n=120) under controlled ovarian hyperstimulation with GnRH agonist protocol at the risk of OHSS (≧20 follicles >12 mm development with E2> 4000 pg/ml) randomized into two groups. Group I (n=60), withdrawing GnRH agonists and continued low dose r-FSH 75 IU. Group II (n=60), GnRH antagonist administration and continued low dose r-FSH 75 IU. When E2< 3000 pg/ml, hCG was given. Oocyte retrieval was performed 36 h after hCG administration. The primary outcome measures were the decreased levels of estradiol (E2) and the days of coasting. The secondary outcome measures were number of oocytes retrieved, pregnancy rate and the incidence of OHSS.

anticipated results: No significant differences were seen in the levels of estradiol (E2) decreased, the days of coasting, number of oocytes, pregnancy rate and the incidence of OHSS. GnRH antagonist is not necessary in coasting treatment while stop GnRH agonist.

Inclusion Criteria:

• the risk of ovarian hyperstimulation syndrome

Exclusion Criteria:

• allergic to GnRH antagonist