Indirect antiglobulin test

No agglutination (i.e., the absence of clumping of red blood cells) is normal.

An abnormal indirect Coombs' test may indicate the presence of an antibody against an antigen that the body views as foreign:

• Antibodies to antigens not present on the individual's red cells, usually caused by prior transfusions
• Erythroblastosis fetalis/hemolytic disease of the newborn
• Incompatible cross-matched blood (when the test is used in the blood bank)

If you have antibodies against your own red cells, the indirect Coombs' test results may be abnormal if there are excess antibodies beyond what your red blood cells can absorb. This may indicate autoimmune hemolytic anemia or drug-induced hemolytic anemia.