Congenital syphilis laboratory findings

Diagnosis of congenital syphilis can be done prenatally and after birth. The investigations include serological tests, PCR of the amniotic fluid, long bone radiographs, ultrasound and CSF analysis. PCR of the amniotic fluid and ultrasound are commonly preferred diagnostic modalities in the prenatal period. Long bone radiographs along with serological tests and CSF analysis are preferred after birth.

• Detection of IgM antibodies aganist T.pallidum in the blood collected by chordocentesis.^[1][2]
• PCR of the amniotic fluid to detect T. pallidum DNA.^[3]
• Antenatal ultrasound is commonly done and the findings suggestive of congenital syphilis include: hydrops fetalis characterised by scalp edema, placental thickening, serous cavity effusion, and polyhydramnios. Other additional findings inlcude hepatosplenomegaly, placentomegaly, non-continuous gastrointestinal obstruction and dilatation of the small bowel.^[4][5][6]

• Examination of the placenta or umbilical cord using a silver stain demonstrates spirochetes or a T. pallidum PCR test can be done.
• The use of serological tests to identify the infection in infants less than 15 months of age born to infected mothers is not performed as passive transfer of IgG antibodies to the fetus occurs during the pregnancy.
• Other laboratory findings in the new born include:^[7]
• Elevated liver enzymes
• Leucocytosis
• Coombs negative hemolytic anaemia
• Thrombocytopenia
• Hypoalbuminemia
• Hyperbilirubinemia

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