Treponema pallidum hemagglutination assay (TPHA) a treponemal antigen serologic test for syphilis using tanned sheep red blood cells that have been coated with antigen from a strain of Treponema pallidum and treated patient serum. This test is similar in sensitivity and specificity to the FTA-ABS test , but is not useful for persons who have had syphilis in the past.
