Metronidazole prophylaxis before surgical abortion: retrospective review of 51 330 cases

To determine the effectiveness of a simple prophylactic antibiotic protocol in preventing postoperative infections, and to determine the risk factors most effective in predicting the presence of intercurrent Chlamydia infection.

A retrospective cohort review of postoperative infection was carried out among women undergoing surgical abortion at four Canadian clinics from 2001 to 2006. All women received antibiotic prophylaxis using uniform observed single-dose metronidazole, with additional observed single-dose azithromycin for those meeting criteria for higher risk of infection.

The records of 51 330 women who underwent surgical abortion using this protocol were reviewed; 38% met criteria predicting a higher risk of infection, and 3.4% were Chlamydia-positive. Risk-factor screening correctly identified 69% of women with Chlamydia. Follow-up was available for 13 999 women (27%). Among these women, 17 (0.12%) developed postoperative infection requiring hospital admission.

Antibiotic prophylaxis prior to surgical abortion using universal metronidazole, with selective azithromycin for women meeting criteria for a higher risk of infection, was associated with a low rate of postoperative infection among those for whom follow-up information is available. This regimen offers the advantages of observed single-dose treatment. Prospective evaluation including outcome assessment for a higher proportion of the study population is warranted.