Screening for Syphilis in Pregnant Women

The US Preventive Services Task Force (USPSTF) has recently published recommendations on screening for syphilis infection in pregnant women.

Syphilis is a sexually transmitted infection caused by bacteria called Treponema pallidum. There are different stages of syphilis, and each stage has different symptoms. Primary syphilis occurs 2 or 3 weeks after infection, with symptoms of small, painless lesions called chancres in areas of sexual contact. Because chancres are painless and go away on their own, many people do not seek treatment. This can lead to secondary syphilis a few weeks to months later. Symptoms of secondary syphilis include flu-like symptoms, fever, a widespread rash, and swollen lymph nodes. If still untreated, these symptoms resolve and a period of latent syphilis follows, during which people may have no symptoms and which can last for several years. Finally, symptoms of tertiary syphilis (late-stage syphilis) can arise, which include serious damage to many organs, such as the heart, brain, spinal cord, and bones.

At any stage of syphilis infection, the infection can be transmitted to a fetus during pregnancy and can result in miscarriage, stillbirth, or severe birth defects. Syphilis is treatable at any stage with antibiotics (usually penicillin).

Screening for syphilis is done by blood tests. These blood tests are usually done in a 2-step process, with the second test acting as a confirmatory test if the first test result is positive. These tests look for the presence of antibodies in the blood against syphilis, not the syphilis bacterium itself.

This USPSTF recommendation applies to all pregnant women.

There is convincing evidence that the benefits of early detection and treatment of syphilis in pregnant women are substantial, namely curing the infection and preventing harmful pregnancy outcomes including fetal and neonatal death. Treatment earlier in pregnancy is more effective than later; therefore, screening is recommended early in pregnancy. Potential harms of screening are likely to be small and include false-positive results that lead to further testing, anxiety, and possible stigma. Potential harms of treatment are also small, as penicillin is safe during pregnancy.

Based on current evidence, the USPSTF concludes with high certainty that the benefits of screening for syphilis in pregnant women substantially outweigh the harms.

Source: US Preventive Services Task Force. Screening for syphilis infection in pregnant women: US Preventive Services Task Force reaffirmation recommendation statement [published September 4, 2018]. JAMA. doi:10.1001/jama.2018.11785