Randomised controlled trial of prophylactic antibiotics before insertion of intrauterine devices. IUD Study Group.

BACKGROUND: The value of antibiotic prophylaxis before insertion of an intrauterine device (IUD) remains uncertain. We undertook a triple-masked, randomised, placebo-controlled trial to find out whether such prophylaxis reduces the rate of IUD removal within 90 days.

METHODS: 11 clinic sites in southern California enrolled women who requested IUD insertion and were at low risk of sexually transmitted infection according to self-reported medical history. We randomly assigned 1985 participants either 500 mg azithromycin or placebo capsules of identical appearance taken about 1 h before insertion of a Copper T 380A IUD. 118 women did not have an IUD inserted. We followed up 1833 of the remaining 1867 (98%) participants for at least 90 days after insertion.

FINDINGS: The rate of IUD removal for any reason other than partial expulsion was 3.8% (35/918) in the antibiotic group and 3.4% (31/915) in the placebo group (relative risk 1.1 [95% CI 0.7-1.8]). The two treatment groups sought medical attention with equal frequency (mean 38 visits per 100 women). During the 90 days after IUD insertion, only one woman from each assignment group had salpingitis, as defined by established criteria.

INTERPRETATION: Prophylaxis with azithromycin did not affect the likelihood that a woman would retain her IUD at 90 days or the frequency of postinsertion medical attention. In appropriately screened women, the risk of upper-genital-tract infection is negligible after IUD insertion, with or without the administration of prophylactic antibiotics.