Effects of initiation day of clomiphene citrate on the endometrium of women with regular menstrual cycles.

Objective: To investigate the effects of initiation time of clomiphene citrate (CC) on the endometrium of women with regular menstrual cycles.

Design: Randomized, double-blind, cross-over study.

Setting: Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.

Patient(s): Thirty-three healthy female volunteers with regular menstrual cycles.

Intervention(s): The volunteers were randomized to receive either 100 mg of CC on days 1-5 and placebo on days 5-9 (study group) or placebo on days 1-5 and CC on days 5-9 (control group). After a wash-out period of 1 month of CC treatment, the medication was switched in each group. Ultrasonography was performed daily after day 10 of the cycle to detect ovulation. Ultrasonography for endometrial appearance and thickness, endometrial sampling, and blood samples obtained for determination of E(2) and P levels were performed 7 days after ovulation in both groups.

Main Outcome Measure(s): Morphometric analysis, histologic dating, and ultrasonographic appearance and thickness of the endometrium.

Result(s): Morphometric parameters, histologic dating, and ultrasonographic appearance and thickness of the endometrium were similar in both groups.

Conclusion(s): Starting CC on either day 1 or day 5 of the menstrual cycle did not have any differential effects on the endometrium of women with regular menstrual cycles, particularly regarding the morphometric analysis, histologic dating, or ultrasonographic appearance.