A double-blind randomized study of the effect of erythromycin in preventing pelvic inflammatory disease after first trimester abortion.

OBJECTIVE

To assess the prophylactic use of erythromycin in prevention of post-abortal pelvic inflammation disease (PID) in first trimester abortion.

DESIGN

Double-blind, randomized controlled trial.

SETTING

Department of Surgery, County Hospital, Denmark.

SUBJECTS: Four hundred and thirty two women who were to undergo induced abortion before 12 weeks gestation were randomized to be treated either with prophylactic erythromycin or a placebo.

INTERVENTION: The women were randomized to receive a placebo or erythromycin, 500 mg twice a day for 7 1/2 days starting the evening before the abortion. All the women were investigated for Chlamydia trachomatis and Neisseria gonorrhoea before the abortion.

MAIN OUTCOME MEASURES: Frequency of cervical C. trachomatis and N. gonorrhoea and frequency of PID after abortion.

RESULTS

Fifty four women were excluded after randomization. The frequency of PID was 11% (20/189) in the erythromycin group and 16% (30/189) in the placebo group (P = 0.13, chi 2-test). The prevalence of C. trachomatis was 19% (15/78) in women less than or equal to 20 years of age, 13% (14/109) in women between 21 and 25 years and 2% (5/241) in women greater than or equal to 26 years of age. In women positive for C. trachomatis erythromycin prophylaxis significantly reduced the frequency of PID to 8% (1/13) compared with 43% (6/14) in the placebo group (P = 0.051, logistic regression analysis). Erythromycin had no effect on other potential high risk groups (first pregnancy, nulliparous, less than 20 years of age, and women with previous PID).

CONCLUSION

Prophylactic erythromycin is not warranted for all women having an abortion. Cervical C. trachomatis is a risk factor for postabortal PID, and prophylaxis with erythromycin significantly reduces the frequency of PID. However, only a few women with PID had cervical C. trachomatis, and the prevention of post-abortal PID remains a major challenge requiring further studies.