Relationship of baseline ovarian volume to ovarian response in World Health Organization II anovulatory patients who underwent ovulation induction with gonadotropins.

Objective: To assess whether ovarian volume of World Health Organization II anovulatory patients in the early follicular phase predicts the response to ovulation induction with gonadotropins.

Design: Retrospective data analysis of two prospective, randomized, multicenter studies.

Setting: Clinical development unit of biotechnology company.

Patient(s): Four hundred sixty-five World Health Organization II anovulatory patients undergoing ovulation induction.

Main Outcome Measure(s): Ovarian response to stimulation, ovulation (mid-luteal serum progesterone > 30 nmol/L), cancellation rate, pregnancy rate, and incidence of the ovarian hyperstimulation syndrome (OHSS) according to baseline ovarian volume (day 2-5) before stimulation.

Result(s): Mean ovarian volume was 11.55 +/- 6.0 cm(3) (range, 0.8-49.3 cm(3)). Small ovarian volume was associated with lower rates of cycle cancellation owing to risk for OHSS (3 vs. 29 patients [2.8% vs. 9%]). Patients with small ovarian volume (<7.25 cm(3)) required fewer ampules of FSH (1373 IU vs. 1629 IU) and shorter duration of stimulation (16 vs. 18.1 days) and had higher ovulation rate than did patients with mid-range and larger ovarian volume (84.3% vs. 69.1% and 68.8%, respectively). The clinical pregnancy rate per cycle of hCG administration was similar in the three groups (25.8%, 28.1%, and 27.5%).

Conclusions: World Health Organization II anovulatory women with medium-sized or large ovaries who are undergoing low-dose gonadotropin stimulation for ovulation induction may have higher risk for OHSS than do women with small ovaries. Women with small ovaries who meet criteria for administration of hCG respond better to ovulation induction and have a similar likelihood of conceiving compared with women with larger ovaries.