Coombs' test

In medicine, the Coombs' test is a "hemagglutination test in which Coombs' reagent (antiglobulin, or anti-human globulin rabbit immune serum) is added to detect incomplete (non-agglutinating, univalent, blocking) antibodies coating erythrocytes. The direct test is applied to red cells which have been coated with antibody in vivo (e.g., in hemolytic disease of newborn, autoimmune hemolytic anemia, and transfusion reactions). The indirect test is applied to serum to detect the presence of antibody (e.g., in detection of incompatibility in cross-matching tests, detection and identification of irregular antibodies, and in detection of antibodies not identifiable by other means).'