Objective: To provide an in-depth assessment of the effects of the combined oral contraceptive containing 30 microg of ethinyl estradiol and 3 mg of drospirenone (Yasmin, Schering AG, Berlin) on the endometrium by means of endometrial morphometry in comparison to an untreated cycle.
Design: The open, multicenter study consisted of one untreated precycle and 13 treatment cycles.
Setting: Four gynecologic clinics in Belgium, The Netherlands, and Switzerland were involved.
Patient(s): Forty women with a history of regular menstrual cycles.
Intervention(s): Before the commencement of the trial, 3 months without any hormonal intake was obligatory. The first endometrial sample was done in the untreated precycle, adjusted to the day of LH peak plus 5 to 6 days. During the medication phase, endometrial samples were taken at cycle 3, 6 and 13.
Main outcome measure(s): Primary outcome measure of the study was the morphologic assessment of the endometrium with measures such as glandular diameter, glandular epithelial height, and number of vacuolated cells per 1,000 glandular cells. Furthermore, the endometrial thickness was measured by ultrasound.
Result(s): After 13 cycles of medication use the endometrium had an atrophic appearance in 63% of the subjects. The size of the glands, the glandular epithelial height, and the number of glands per square millimeter were already significantly reduced after 3 months' use. Histological and ultrasonographical evaluation of the endometrium indicated a suppression of the proliferative activity of the endometrium.
Conclusion(s): The combination of 30 microg of ethinyl estradiol with 3 mg of drospirenone induces changes of the endometrium that are comparable with other combined oral contraceptives and exhibits a marked antiproliferative effect on the endometrium. The medication was proven to be an effective oral contraceptive and revealed good cycle control characteristics.