Congenital syphilis laboratory findings
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Kalsang Dolma, M.B.B.S.[2]; Aditya Govindavarjhulla, M.B.B.S. [3]
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Laboratory Findings
- Blood tests
- Complete blood count
- Differential count
- Platelet count
- CSF analysis
- VDRL tests
- Cell counts
- Protein
Serology
The diagnosis of congenital syphilis is complicated by the transplacental transfer of maternal nontreponemal and tre-ponemal IgG antibodies to the fetus. This transfer of antibodies makes the interpretation of reactive serologic tests for syphilis in infants difficult.
All infants born to mothers who have reactive nontreponemal and treponemal test results should be evaluated with a quantitative nontreponemal serologic test (RPR or VDRL) performed on infant serum because umbilical cord blood can become contaminated with maternal blood and could yield a false-positive result. Conducting a treponemal test (i.e., TP-PA or FTA-ABS) on a newborn’s serum is not necessary. No commercially available immunoglobulin (IgM) test can be recommended.
Dark Microscopic Examination
Darkfield microscopic examination or DFA staining of suspicious lesions or body fluids (e.g., nasal discharge) also should be performed.
Standard Tests
- Antibody Screening Tests (nontreponemal)
- Rapid plasma reagin (RPR)
- Venereal Disease Research Laboratory (VDRL)
- Unheated serum reagin (USR)
- Reagin screen test (RST)
- Antibody Confirmatory Tests (treponemal)
- Fluorescent treponemal antibody absorption (FTA-ABS)
- Fluorescent treponemal antibody absorption double staining (FTA-ABS DS)
- Microhemagglutination assay for antibody to T. pallidum (MHA-TP)
- Hemagglutination treponemal test for syphilis (HATTS)
- Bio-enzaBead Test (ELISA)
- Direct Examination of Lesion or Tissue
- Darkfield microscopy
- Direct fluorescent antibody test for T. pallidum (DFA-TP)
- Silver stains (modified Steiner)
- Hematoxylin and eosin (H & E) stains
Experimental Tests
- FTA-ABS immunoglobulin (IgM)
- FTA-ABS 19S IgM
- IgM capture ELISA