Coombs Test - Indirect
Understanding Coombs Test - Indirect
What is Coombs Test - Indirect?
The Indirect Coombs Test (ICT) is also called as Indirect Antiglobulin Test. It is performed to identify the presence or absence of antibodies in blood directed against antigens found on red blood cells.
ICT test is done at the time of donating blood, tissue, or organ, before receiving blood during the transfusion to determine the compatibility with donated blood, and during pregnancy to determine the risk of incompatibility between mother and fetus.
The Indirect Coombs Test is performed on the principle of the antigen-antibody reaction. It is used to detect very low concentrations of antibodies present in a patient’s plasma. The ICT can also be used for compatibility testing, antibody identification, RBC phenotyping, and titration studies.
What is Coombs Test - Indirect used for?
· At the time of donating blood, tissue, organ, or bone marrow or while getting registered as a potential donor
· Before receiving a blood transfusion or blood components transfusion to determine compatibility with donated blood
· Before pregnancy and during pregnancy to determine the risk of incompatibility between the mother and fetus
· To determine if hemolytic anemia is caused due to an autoimmune disorder
Interpreting Coombs Test - Indirect results
Agglutination: Positive result, antibodies present
No agglutination: Negative result, antibodies absent
No antibodies detected
Positive in undiluted serum up to 1:16 titre
Positive in titre of 1:32 or above
Positive in increasing titre in subsequent tests
Antibodies are produced in the blood upon exposure to incompatible antigens as during a blood transfusion. Antibodies produced in the first incompatible transfusion produce severe reactions upon subsequent transfusions of the same blood type.