Preliminary studies indicate that hemagglutination tests for Treponema pallidum antibodies compare favorably with the fluorescent treponemal antibody absorption (FTA-ABS) test for serodiagnosis of syphilis. Hemagglutination tests appear to be as sensitive as the FTA-ABS test in all phases of syphilis except primary syphilis and they are probably more sensitive in treated syphilis. These tests possess a high degree of specificity but as with the FTA-ABS test, they give falsepositive results in a small percentage of cases. Hemagglutination tests are much easier to perform and are more economical than other available treponemal tests. Several laboratories are now considering use of hemagglutination tests for routine confirmation and screening of syphilis.
Shore RN. Hemagglutination Tests and Related Advances in Serodiagnosis of Syphilis. Arch Dermatol. 1974;109(6):854-857. doi:10.1001/archderm.1974.01630060032008