Evaluation of the role of the Treponema pallidum immobilisation test in Britain.

After specimens of sera from 100000 patients had been screened by a reagin and Treponema pallidum haemagglutination assay (TPHA) 2.7% required further examination. The fluorescent treponemal antibody-absorption (FTA-ABS) test confirmed either a negative or positive TPHA result in 95% of the samples, so that no further investigations were required. This accounted for 99% of the specimens submitted to the laboratory. Repeat tests on a further sample resolved many of the remaining discrepancies. Only 0.05% of patients, in whom repeat tests confirmed a positive TPHA but a negative FTA-ABS result, benefited from a TPI test.