A test for the presence in human blood of antibodies. The antibodies present in the blood do not, themselves, cause agglutination. It is the addition of an antibody made in animals (antiglobulin) that stimulates red blood cell clumping. The direct antiglobulin test (DAT) is used to diagnose autoimmune hemolytic anemia and hemolytic disease of the newborn. The indirect antiglobulin test (IAT), or Coomb’s test, is used to identify blood types.