Screening Pregnant Women for Bacterial Vaginosis: U.S. Preventive Services Task Force Recommendations

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The summary below is from the full reports titled "Screening for Bacterial Vaginosis in Pregnancy to Prevent Preterm Delivery: U.S. Preventive Services Task Force Recommendation Statement" and "Evidence on the Benefits and Harms of Screening and Treating Pregnant Women Who Are Asymptomatic for Bacterial Vaginosis: An Update Review for the U.S. Preventive Services Task Force." They are in the 5 February 2008 issue of Annals of Internal Medicine (volume 148, pages 214-219 and 220-233). The first report was written by the U.S. Preventive Services Task Force; the second report was written by P. Nygren, R. Fu, M. Freeman, C. Bougatsos, M. Klebanoff, and J.M. Guise.

Who developed these guidelines?

The U.S. Preventive Services Task Force (USPSTF) is a group of health experts that makes recommendations about preventive health care.

What is the problem and what is known about it so far?

Bacterial vaginosis is caused by the overgrowth of bacteria that normally live in the vagina. Often, women with bacterial vaginosis have no symptoms, but some women have vaginal discharge, odor, or itching. Studies show that pregnant women with bacterial vaginosis are more likely than women without the condition to have babies that are premature or low birthweight. Doctors can test for the condition by swabbing the cervix during pelvic examination and sending the swabs to the laboratory. To treat bacterial vaginosis, a woman takes an antibiotic either by mouth or by a gel inserted into the vagina. Because poor pregnancy outcomes are associated with bacterial vaginosis and because screening (that is, testing for the condition in people who have no symptoms) and treatment for the condition are easy to perform, some experts favor screening all pregnant women for bacterial vaginosis. However, it is unclear whether screening pregnant women for bacterial vaginosis and treating those with the condition actually improve pregnancy outcomes.

How did the USPSTF develop these recommendations?

The USPSTF reviewed published research to evaluate the benefits and harms of screening and treating asymptomatic pregnant women for bacterial vaginosis. Potential benefits include full-term, normal-birthweight babies and other healthy pregnancy outcomes. Harms include side effects of antibiotic treatment or poor pregnancy outcomes due to treatment. They considered information for women at low risk for poor pregnancy outcomes, such as those who had no previous preterm delivery, and for women at high risk, such as those who had previous premature delivery.

What did the authors find?

No studies directly showed that screening for bacterial vaginosis improves pregnancy outcomes for women at low or high risk for preterm delivery. Good evidence indicated that treating bacterial vaginosis does not benefit pregnant women at low risk for premature delivery. Studies about whether treatment benefits women at high risk for preterm delivery had conflicting results. Although good studies on the harms of screening for bacterial vaginosis are not available, the authors found fair evidence that false-positive results can occur and lead to unnecessary treatment of women who do not really have the condition.

What does the USPSTF suggest that patients and doctors do?

The USPSTF recommends against screening for bacterial vaginosis in pregnant women at low risk for premature delivery. The USPSTF believes that information is insufficient to recommend either for or against screening for bacterial vaginosis in pregnant women at high risk for premature delivery.

What are the cautions related to these recommendations?

These recommendations do not apply to pregnant women who have symptoms of bacterial vaginosis. The recommendations may change as new studies become available.