Corifollitropin alfa, single dose administered sustains multiple follicular development for 7 days. However, It may induce ovarian hyperstimulation syndrome (OHSS), especially in high responder women such as patients of polycystic ovary syndrome (PCOS). In GnRH antagonist protocol with agonist triggering of final oocyte maturation, following embryo cryopreservation can almost eliminate the risk of OHSS. To decrease the injection burden and prevent OHSS in PCOS patients undergoing IVF treatment, ovarian hyperstimulation with Corifollitropin alfa in GnRH antagonist protocol and GnRH agonist triggering of final oocyte maturation, following elective embryo cryopreservation was designed in this study. The purpose of this trial was conducted to confirmed whether this novel protocol could prevent OHSS, decreased the injection burden of PCOS patients and single dose corifollitropin alfa could support multiple follicular growth for 7 days.

BACKGROUNG: Ovarian hyperstimulation syndrome (OHSS) is the most serious complication of ovulation induction. Therefore, Corifollitropin alfa, long acting recombinant follicular stimulation hormone (rFSH) application in PCOS women is warning. However, corifollitropin alfa could decrease the injection burden of patients undergoing IVF/ICSI treatment. In previous studies, embryo cryopreservation following GnRH agonist triggering final oocyte maturation in GnRH antagonist protocol can almost eliminate the risk of OHSS. This study was designed to analyze whether ovarian hyperstimulation in PCOS women with Corifollitropin alfa in GnRH antagonist protocol and GnRH agonist triggering, following freezing all embryos can decrease the injection burden without OHSS complication.

PURPOSE: To assess whether single dose Corifollitropin alfa sustains multiple follicular growth for seven days in GnRH antagonist protocol application in PCOS women, following embryo cryopreservation after GnRH agonist triggering can decrease injection benefit without OHSS complication.

METHODS: This prospective ,single center, observational study, thirty to fifty PCOS women aged 20-38 years old, In GnRH antagonist protocol, a single dose corifollitropin alfa was administered for ovarian stimulation (S1, stimulation D1). Seven days later, rFSH was daily injected to stimulate follicle development according to the ovarian response. GnRH antagonist was administered daily from S5 until the day of final oocyte maturation. GnRH agonist was given to replace hCG to trigger final oocyte maturation when three follicles reached 17 mm in size. The IVF or ICSI was planned then all embryos were elective cryopreservation. Transfer of embryos was performed in a subsequent frozen-thawed ET cycles. Primary outcome measure was the incidence of OHSS. The secondary outcome measures were numbers of oocytes retrieval, numbers of embryos frozen and pregnancy rate of subsequent FET cycles.

ANTICIPATED RESULTS: Decreasing the injection burden and maximal oocytes were retrieved without severe OHSS complication.

Inclusion Criteria:

The diagnosis of PCOS was according Rotterdam criteria ( twoi of three) included:

• chronic anovulation manifested by the symptoms of oligomenorrhoea
• ultrasonographic evidence of polycystic enlarged ovary with over 10 peripherally located follicles of 3-8mm diameter around a dense central stroma
• hyperandrogenaemia (serum testosterone concentrations over 0.8 ng/ml) or clinical hyperandrogenism.

Exclusion Criteria:

• A diagnosis of congenital adrenal hyperplasia, Cushing's syndrome, androgen-producing tumours, hyperprolactinaemia and thyroid dysfunction were all excluded.
• patients older than 38 years or with serum FSH level over 12 mIU/ml.
• patients wiht previous ovarian surgery
• husband with non-obstructive azoospermia