Congenital Syphilis

Congenital syphilis is syphilis passed from a mother to her baby during pregnancy or birth. It can cause miscarriage, stillbirth, premature birth and death of the newborn. Babies who survive may have no symptoms at first, or may have a rash, a runny nose, an enlarged liver and spleen, jaundice, anemia, bone problems and low birth weight. Later problems can include damage to the teeth, bones, eyes, ears and brain. Cases have risen sharply in the US in recent years. It is preventable: syphilis testing in pregnancy and treatment with penicillin protect the baby.

Lab tests linked to congenital syphilis:

• RPR and VDRL: quantitative nontreponemal tests for syphilis. The baby's result is compared with the mother's result on the same test, ideally in the same lab. Treponemal tests aren't routinely used to confirm infection in newborns, because the mother's antibodies can persist in the baby.
• Diagnosis is based on the mother's syphilis tests and treatment history, the baby's examination and the baby's RPR or VDRL titer. Doctors may also test the baby's spinal fluid (CSF VDRL, cell count and protein), and do a CBC, liver tests, long-bone X-rays and an eye exam.

How results are read:

• A baby's RPR titer that is fourfold or more higher than the mother's strongly suggests congenital syphilis.
• Antibodies from the mother can cross the placenta, so a reactive test in the baby doesn't always mean infection. Titers that fall to non-reactive over time point to passed-on antibodies.
• Whether and how the mother was treated during pregnancy is key to deciding the baby's risk and treatment.

When to see a doctor:

• Get tested for syphilis during pregnancy. ACOG recommends screening at the first prenatal visit, in the third trimester and at birth.
• If you were treated for syphilis in pregnancy, make sure your baby's doctor knows.
• Get emergency care for a newborn who is floppy, feeding poorly, very sleepy, or has a fever.

Clinical takeaway: congenital syphilis is assessed by comparing the baby's RPR or VDRL with the mother's, together with her treatment history, and is prevented by testing and treatment during pregnancy.