Key messages
We are uncertain whether routine antibiotics have any effect on the risk of getting a uterine infection (infection in the womb) after surgery to manage a miscarriage, based on the combined results from all six trials.
However, based on the results from only the well-done trials (85% of the total number of women in the studies), we are confident that routine antibiotics reduce the risk of getting a uterine infection after surgery to manage a miscarriage.
We are uncertain whether routine antibiotics have any effect on the risk of vomiting and diarrhoea, but they may increase the risk of an allergic reaction. We are uncertain about other effects of routine antibiotics, such as future treatment and hospitalisation for a uterine infection.
What is miscarriage or early pregnancy loss?
Early pregnancy loss (previously called miscarriage) is the unintended loss of a baby before 24 to 28 weeks of pregnancy. Almost one in six women will lose a baby during pregnancy in their lifetime. Worldwide, it is estimated that 23 million early pregnancy losses occur every year, which equates to 44 early pregnancy losses every minute.
Early pregnancy loss can be managed in three ways: women can wait for the remaining pregnancy tissue to pass by itself, they can take medicine to help expel the tissue, or they can undergo a procedure to remove the pregnancy tissue from the uterus. Procedures to manage early pregnancy loss (previously referred to as surgical management or uterine evacuation) are commonly performed, but increase the risk of women developing an infection in the womb when compared to other ways of treating early pregnancy loss.
Infection after early pregnancy loss has been reported to be as high as 30% in some low-income countries. It can cause death and disability. It can also have long-term consequences for fertility.
Antibiotics are routinely given before or during many surgical procedures to prevent the development of an infection (known as antibiotic prophylaxis). This includes procedures to perform an abortion (also known as a termination of pregnancy).
What did we want to find out?
We wanted to evaluate whether giving antibiotics around the time of the procedure to manage early pregnancy loss would help lower the women's risk of infection, and whether their routine use was associated with any serious side effects.
What did we do?
We collected and analysed all relevant studies from the medical literature to answer this question. We identified six randomised studies (everyone had the same chance of receiving one of the treatments). They were carried out across eight countries, and included 4371 women who had procedures to manage early pregnancy loss. The women were given either antibiotics, a placebo (fake antibiotics), or no treatment.
What did we find out?
When we combined the results from all six studies, we were uncertain whether routine antibiotics made any difference in the risk of getting a uterine infection. However, when we only looked at the combined findings from the three studies that were well conducted, and which included 85% of the women, we are confident that routine antibiotics reduce the risk of infection in the uterus after procedures for early pregnancy loss.
We cannot be certain whether routine antibiotics reduce future hospitalisation for the treatment of infection, or reduce the need for further antibiotics to treat infection.
What are the limitations of the evidence?
Not all the women stayed in their studies until the end; some did not finish their medicine. There was limited information on the side effects of the antibiotics, such as vomiting, diarrhoea, and allergic reactions, both mild and severe.
How up-to-date is the evidence?
The evidence is up-to-date to October 2023.
When all studies were considered, the evidence suggested that routine antibiotic prophylaxis may reduce uterine infection amongst women undergoing uterine evacuation procedures to manage early pregnancy loss (EPL), but the evidence is of low certainty. It is important to note that the quality of the evidence included was seriously affected by poor follow-up and high non-compliance with antibiotic prophylaxis. A sensitivity analysis based on three trials assessed to have low risk of bias (85% of the total participants), demonstrated a larger effect size with high certainty, resulting in a 43% reduction in the risk of uterine infection rates with antibiotic prophylaxis.
Prophylactic antibiotics may reduce hospitalisation for treatment of infection, and may reduce the need for a course of antibiotics to treat infection after uterine evacuation procedures to treat EPL, but this evidence is very uncertain. Data were limited and uncertain with regard to potential adverse effects, such as vomiting, diarrhoea, allergy, and anaphylaxis.
Procedural management of early pregnancy loss (EPL) involves removing any residual pregnancy tissue from the uterus. Clinical evidence and guidance are clear that antibiotic treatment is needed for women experiencing EPL, with signs and symptoms of infection. However, it is less clear whether prophylactic antibiotics are routinely required during procedural management in those without features of infection.
To evaluate the effectiveness of routine antibiotic prophylaxis for women undergoing uterine evacuation procedures to manage early pregnancy loss.
We searched the Cochrane Fertility Regulation Review Group trials register, CENTRAL, MEDLINE, Embase, Global Health (Ovid), Scopus (conference abstracts only), and grey literature in October 2023. We checked references and contacted study authors and experts in the field to identify additional studies.
We included randomised controlled trials comparing prophylactic antibiotics with placebo or no treatment. Trials with a cluster‐randomised design and trials published only in abstract form were also eligible for inclusion. We included all types of EPL managed with surgical uterine evacuation. There was no gestational age limit. We excluded women with signs and symptoms of infection.
Two review authors independently assessed trials for inclusion and risk of bias, extracted and checked data for accuracy, and assessed the certainty of evidence using the GRADE approach. We contacted the authors of the ongoing trial for additional information.
We included six RCTs with a total of 4371 participants undergoing uterine evacuation procedures to manage EPL. Prophylactic antibiotics may have little or no effect on uterine infection after uterine evacuation for EPL compared with placebo or no treatment, but this evidence was uncertain (risk ratio (RR) 0.78, 95% confidence interval (CI) 0.47 to 1.28; I² = 50%; 6 studies, 4371 participants; low-certainty evidence).
Sensitivity analysis of three studies including 3737 participants (85% of total participants) showed that when only studies with low risk of bias were meta-analysed, the effect was larger and of high certainty, resulting in a 43% reduction in the risk of developing a uterine infection (RR 0.57, 95% CI 0.37 to 0.86; I² = 0%; 3 studies, 3737 participants; high-certainty evidence). Both the overall estimate and the sensitivity analysis limited to studies with low risk of bias were consistent with a reduction in uterine infection with prophylactic antibiotics.
A single study reported on adverse effects. Prophylactic antibiotics likely result in little or no difference in the risk of vomiting (RR 1.20, 95% CI 0.61 to 2.38; 1 study, 3404 participants; moderate-certainty evidence), and likely result in little or no difference in the risk of having diarrhoea (RR 0.92, 95% CI 0.51 to 1.65; 1 study, 3404 participants; moderate-certainty evidence). Prophylactic antibiotics may increase the risk of allergy (RR 3.01, 95% CI 0.12 to 73.76; 1 study, 3404 participants; low-certainty evidence); the study reported no cases of anaphylaxis (very low-certainty evidence).
Prophylactic antibiotics may reduce the need for antibiotic treatment to treat infection, but the evidence is very uncertain (RR 0.94, 95% CI 0.54 to 1.64; I2 = 63%; 3 studies, 3574 participants; very low-certainty evidence).
Meta-analysis of three studies also found that prophylactic antibiotics may reduce hospitalisation for treatment of infection, but the effect was very uncertain (RR 0.76, 95% CI 0.40 to 1.46; I² = 0%; 3 studies, 3859 participants; very low-certainty evidence).