Secretion of inhibin B during ovarian stimulation is decreased in infertile women with endometriosis

Objective(s): To determine the levels and pattern of inhibin B secretion during ovarian stimulation in patients with endometriosis and to evaluate the correlation between inhibin B levels and variables of follicular and oocyte development. Design: Retrospective cohort study. Setting: IVF center. Patient(s): Women with endometriosis (n = 20) and tubal factor (n = 10) as the only cause of infertility. Intervention(s): Inhibin B levels were measured during gonadotropin stimulation on day 1, days 8-11, day of hCG administration, and oocyte retrieval. Main Outcome Measure(s): Patterns and levels of inhibin B secretion were compared in the two groups. Other variables analyzed were age, days of gonadotropin stimulation and total ampules used, oocytes retrieved, and the fertilization and pregnancy rate. Result(s): Inhibin B levels and number of oocytes retrieved were significantly lower in patients with endometriosis than in the control group. Two patterns of inhibin B secretion were noted: It peaked in the midfollicular phase or on the day of hCG administration. In contrast, E-2 levels peaked on the day of hCG administration. Inhibin B in the midfollicular phase in both groups correlated positively with number of oocytes retrieved. In addition, E-2 and inhibin B levels in the midfollicular phase correlated positively. Conclusion(s): Decreased inhibin B secretion in patients with endometriosis suggests impaired granulosa cell function. Inhibin B may serve as an alternate marker to assess follicular development or to predict the number of oocytes retrieved. (Fertil Steril(R) 2000;74:35-40. (C) 2000 by American Society for Reproductive Medicine).