antiglobulin test, a test for the presence of antibodies that coat and damage erythrocytes as a result of any of several diseases or conditions. The test can detect Rh antibodies in maternal blood and is used to anticipate hemolytic disease in the newborn. It is also used to diagnose and screen for autoimmune hemolytic anemias and to determine the compatibility of blood types. When exposed to a sample of the patient’s serum, the antiglobulin serum causes agglutination if human globulin antibody or its complement is present. Also called Coombs’ test.