Test Details: Syphilis is a sexually transmitted disease (STD) caused by the bacteria Treponema pallidum. Treponemal tests are usually performed to confirm an infection after a patient has a positive result on a non-treponemal screening test. Treponema pallidum hemagglutination (TPHA) is one of the treponemal tests performed. It helps in the detection of Palladium antibodies via the hemagglutination method. This diagnostic test is used to detect the dissolved amount of antibodies in the serum sample of a patient against the causative agents of syphilis. The process involves sensitizing the red blood cells with T. palladium fragments. When exposed to the serum sample infected with syphilis, the cells aggregate on the surface of the test dish.