Ovulation inhibition with a combined oral contraceptive containing 1 mg micronized 17 beta-estradiol

Abstract

Objective: To evaluate ovarian function by ultrasonography and endocrine measurements.

Design: Prospective, open study.

Setting: Outpatient clinic of the First Department of Gynaecology and Obstetrics, University of Vienna, Austria.

Participants: Twenty healthy women with regular cycles and established ovulation by ultrasonography.

Intervention: Treatment with a combination of 1 mg micronized E2 with 150 micrograms desogestrel daily for 21 days, followed by 7 pill-free days.

Main outcome measures: Transvaginal ultrasonography and estimation of E2 and P at least twice a week for two consecutive cycles, followed by one after treatment cycle.

Results: Ovulation inhibition was apparent in all cases and no functional ovarian cysts were observed during treatment. On a few occasions a persistent follicle was noted, but in the majority of cases there was total absence of follicular activity. The bleeding pattern showed a tendency toward prolonged and more heavy bleeding when compared with the before treatment situation. Return of ovulation was prompt in all women but one.

Conclusions: Ultrasonographic observations, accompanied by P and E2 measurements, allow us to conclude that the combination of 1 mg E2 with 150 micrograms desogestrel provides complete ovulation inhibition. However, the bleeding pattern does not show an acceptable profile.

PIP: Treatment of 20 women with a combined oral contraceptive (OC) containing 1 mg of micronized 17beta-estradiol and 150 mcg of desogestrel taken for 21 days achieved successful ovulation inhibition in all cases and there was a marked suppression of follicular activity. The study subjects--Austrian women 21-36 years of age--were evaluated during a baseline cycle, two treatment cycles, and one post-treatment cycle. This is the first investigation of a natural estrogen to use ultrasonographic monitoring of ovarian function and hormonal assays. No functional ovarian cysts were detected. Mean estradiol levels during treatment (50-60 pg/ml after extraction adjustment) were almost twice those obtained before and after OC administration. Moreover, these results challenge earlier assumptions that 4 mg of estradiol are necessary for ovulation suppression. This regimen is not considered appropriate for contraception, however, due to erratic and prolonged bleeding. The median number of bleeding days was 9.5 in the first treatment cycle and 8.0 in the second. This estradiol-desogestrel combination was first developed for use as hormone replacement therapy in menopausal women.