Serological diagnosis of syphilis in pregnancy. Experiences at King Edward VIII Hospital, Durban.

Three different serological screening tests for syphilis were performed at the 'booking' visit of 500 antenatal patients at the King Edward VIII Hospital, Durban. The prevalence of active syphilis was 7,4%. The rapid plasma reagent test not only had a high biological false-positive rate at 11,8%, but also failed to detect 18,9% of the 37 patients diagnosed as having syphilis by means of the IgM-specific fluorescent treponemal antibody absorption (FTA-ABS) test. The Treponema pallidum haemagglutination (TPHA) test had a similarly high biological false-positive rate of 15,8%, but did not miss any of the 37 cases of active syphilis. The TPHA test is therefore advocated for screening patients for syphilis.