The effects of GnRH antagonist on the endometrium of normally menstruating women.

PURPOSE: To study the effects of GnRH antagonist (ganirelix-Orgalutran) on the endometrium of regularly menstruating women.

MATERIALS AND METHODS: Prospective, self-controlled study. The thirty-five volunteers were studied for two cycles: one as a control and the other, GnRH antagonist-treated cycles in which ganirelix 0.25 mg/d was given daily for 3 days, starting when the largest follicle reached 15 mm. In both cycles, serum estradiol, LH and endometrial thickness were measured when the largest follicle was > or =18 mm. Endometrial biopsy was performed on day 6 after ovulation for histological dating and morphometric study.

RESULTS: No statistical differences between histological dating and the endometrial thickness in the control and GnRH antagonist-treated cycles. All morphometric parameters were also not different. Serum estradiol and LH levels were significantly lower in GnRH antagonist-treated cycles.

CONCLUSION: GnRH antagonist has no effect on the endometrium of regularly menstruating women as assessed by either histological dating or morphometric analysis.