Antibiotics In Miscarriage Surgery (AIMS) not linked to lesser infection

The risk of getting a pelvic infection is still high even after antibiotic treatment before the miscarriage surgery, says the findings of a multinational trial published in the New England Journal of Medicine.

The annual global burden of miscarriage is estimated to be 33 million out of 210 million pregnancies. Majority of women get their miscarriage managed through surgery which increases the chance of infection. The surgery is often required to remove the contents of the uterus. But whether prophylactic antibiotics help prevent post-surgical infection remains unclear.

The trial was conducted in low-resource countries by a group of investigators, led by David Lissauer, MBChB, Ph.D., of the University of Birmingham in England, to check whether Antibiotics In Miscarriage Surgery (AIMS) is effective in reducing the odds of getting a pelvic infection. The trial enrolled 3412 participants from Malawi, Pakistan, Tanzania, and Uganda. Out of which 1705 patients were assigned to receive either preoperative dose of 400 mg of oral doxycycline and oral metronidazole, the ratio was kept 1:1. 1707 were assigned to receive placebo. The primary outcome was pelvic infection within 14 days after surgery.

At the start of the trial, the initial primary outcome—pelvic infection 14 days after surgery—was defined according to criteria designated by the US Centers for Disease Control and Prevention and the World Health Organization. Under this definition, the diagnosis of a pelvic infection requires two or more of four clinical features.

But during the trial, there was concern that this strict definition could lead to some missed infections. So the criteria were broadened to require only one of four clinical features of infection, along with the clinician's judgment that the patient had a pelvic infection and needed antibiotics for treatment. The initial primary outcome then became the secondary outcome. The changes were made before the data were unblinded.

The researchers found the risk of infection in the antibiotic group was 4.1% which slightly lesser than the group who received a placebo which is 5.3%. Pelvic infection according to original strict criteria was diagnosed in 1.5% in the antibiotic group and 2.6% in the placebo group.

Pelvic infection was identified by the presence of two or more of four clinical features (purulent vaginal discharge, pyrexia, uterine tenderness, and leukocytosis) or by the presence of one of these features and the clinically identified need to administer antibiotics.

Over 33 million women are at high risk of death, serious illness or long term health problem due to the infection. The occurrence is particularly higher in low-income countries due to the limited facility.

Doxycycline and metronidazole are widely available internationally; both are included on the WHO model list of essential medicines and are widely used in cases like this due to their affordability. But, the findings have shown that these two drugs do not provide enough protection against the 14-day risk of pelvic infection as defined by pragmatic broad criteria. However, the investigators also concluded that that results suggested a possible benefit when pelvic infection was defined by strict criteria.