[Prevalence of false seropositivity for syphilis in a population of pregnant women].

A retrospective chart review of 439 pregnant women with positive syphilis serology detected with VDRL was made. One hundred twenty two women (27.7%), aged 17 to 43 years and with a gestational age ranging from 8 to 38 weeks, had false positive VDRL tests. None of these patients had a titer over 1:4 and 65% had a weakly reactive VDRL. Forty percent of women were diagnosed as having an early latent syphilis and 20% as late latent syphilis. Due to the high frequency of these later diagnoses in women with VDRL titers below 1:2, with no risk factors and negative sexual partners, post partum follow up is essential to detect cases with false positive FTA-ABs tests.