Comparison of maternal and newborn serologic tests for syphilis

S. A. Rawstron and K. Bromberg
Department of Pediatrics, Children's Medical Center of Brooklyn, Kings County Hospital Center, NY.

OBJECTIVE--To compare the cord blood, newborn serum, and maternal serum for the diagnosis of congenital syphilis. DESIGN--Retrospective chart review. SETTING--Kings County Hospital Center, Brooklyn, NY. PATIENTS--Three hundred forty-eight mother-newborn pairs with positive syphilis serology. MEASUREMENTS AND RESULTS--One hundred fifteen newborns (33%) had rapid plasma reagin tests of cord blood that were nonreactive. Their mothers had positive serologic findings. There were 10% false-positive cord blood samples (cord blood rapid plasma reagin tests reactive, newborn serum rapid plasma reagin tests nonreactive) and 5% false-negative cord blood samples (cord rapid plasma reagin tests nonreactive, newborn serum rapid plasma reagin tests reactive). Thirty-three newborns had congenital syphilis. Seven newborns had cord titers fourfold higher than their mothers'; only four of these newborns had congenital syphilis. Maternal serology is superior to cord blood analysis for identifying newborns at risk of congenital syphilis.