The indirect Coombs test is used in prenatal testing of pregnant women and in testing blood prior to a blood transfusion. It detects antibodies against RBCs that are present unbound in the patient's serum. In this case, serum is extracted from the blood sample taken from the patient. Then, the serum is incubated with RBCs of known antigenicity; that is, RBCs with known reference values from other patient blood samples. Finally, anti-human globulin is added. If agglutination occurs, the indirect Coombs test is positive.
Also known as: ICT Blood, Indirect Coombs Test, Coombs Indirect Test.