Oral contraceptives maintain a very thin endometrium before operative hysteroscopy.

OBJECTIVE: To show that early follicular-phase administration of an oral contraceptive pill (OC) consistently provides a thin endometrium, as determined by transvaginal ultrasound. This is an ideal condition when performing operative hysteroscopy.

DESIGN: Retrospective chart review of patients who have undergone ultrasound evaluation of the endometrial thickness under different hormonal conditions. Endometrial measurement was obtained during menstruation, in the late follicular phase, and in the luteal phase in 20 patients. In another group of 100 patients, endometrial measurement was made on the 18th day of OC administration, initiated during menses.

SETTING: A reproductive endocrinology unit in a university-affiliated medical center.

PATIENT(S): Patients undergoing treatment for subfertility of various etiologies.

INTERVENTION(S): Transvaginal ultrasound measurements of the endometrium.

MAIN OUTCOME MEASURE(S): Endometrial thickness by transvaginal ultrasound.

RESULT(S): Combination OCs started on menstrual days 1-3 maintain a uniformly thin endometrium, 4.1 +/- 1.6 mm (mean +/- SD), comparable to menstrual endometrium (3.7 +/- 1.5 mm). This was statistically thinner compared with endometrium observed in the late follicular phase (11 +/- 2.0 mm) or late luteal phase (12 +/- 2.3 mm). Transvaginal ultrasound measurements of the endometrium under different conditions were compared by the unpaired t-test.

CONCLUSION(S): Oral contraceptives maintain a very thin, flat endometrium, such that lesions might be readily identified and treated during operative hysteroscopy procedures. Prevention of pregnancy and endometrial thinning with administration of OCs facilitates procedural scheduling for patients and surgeons.