Diagnostic tests for syphilis are classified into treponemal tests (TT) and non-treponemal tests (NTT).
NTT include the VDRL (Venereal Disease Research Laboratory), USR (VDRL modified for unheated serum), and RPR (Rapid Plasma Reagin, involving the addition of carbon particles and macroscopic reading). These tests measure antibodies produced in response to the infection.
A negative NTT result rules out syphilis; however, if there is suspicion of recent primary syphilis, treatment should be initiated, a TT performed, and the NTT repeated in 2–4 weeks.
If an NTT results positive in a pregnant woman, treatment should be initiated while awaiting confirmatory test results.
To confirm the infection, it is necessary to quantify antibody titers (quantitative VDRL) and perform a TT, without delaying the first dose of treatment.
A negative TT result rules out infection (consider a false-positive NTT result).
A positive TT result confirms the diagnosis of syphilis. In this case, the disease must be staged, the appropriate treatment completed, and the administered treatment recorded; having this information is crucial for evaluating the newborn at delivery.
It is important to note that whenever a pregnant woman is screened, diagnosed, and treated during prenatal care, her newborn must eventually be treated (depending on the maternal diagnosis) and, crucially, must be monitored during the first year of life.
You can find the algorithms for syphilis in pregnancy diagnosis and treatment in the link below.
