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.