Coombs' test, indirect

Normal values:

No agglutination (clumping of cells) is normal.

What abnormal results mean:

• antibodies to antigens not present on the individual's red cells, usually caused by prior transfusions
• erythroblastosis fetalis
• incompatible cross-matched blood

If there are excess antibodies (over and above what the person's red blood cells can absorb):

• autoimmune hemolytic anemia
• drug-induced hemolytic anemia

Additional conditions under which the test may be performed:

• amebiasis
• amebic liver abscess
• congenital Spherocytic Anemia