Final answer:
The indirect Coombs' test or indirect antiglobulin test (IAT) is a diagnostic lab assay used to detect unbound antibodies in a patient's serum targeting red blood cell antigens excluding A and B antigens. It is significant in assessing conditions that may lead to hemolytic disease of the newborn and in ensuring blood transfusion compatibility.
Step-by-step explanation:
Indirect Coombs' Test Overview
The indirect Coombs' test, also known as the indirect antiglobulin test (IAT), is a laboratory assay performed in vitro. This test screens for unbound antibodies in a patient's serum that are directed against red blood cell antigens, excluding the A and B antigens. The presence of these antibodies can indicate conditions such as hemolytic disease of the newborn or compatibility issues before blood transfusions. A few drops of a special Coombs' reagent, containing antihuman antibodies are mixed with the patient’s blood sample to facilitate the test.
The test can also help determine the cause of jaundice in newborns, which is a yellowing of the skin caused by high bilirubin levels due to the breakdown of hemoglobin. Disorders leading to a positive indirect Coombs' test may include autoimmune hemolytic anemia, certain infections, and allergic reactions to drugs, such as penicillin.
While the indirect Coombs' test looks for unbound antibodies in serum, the direct Coombs' test detects antibodies or complement proteins directly attached to red blood cells in vivo. The direct test is often used to diagnose diseases causing antibody-related agglutination of red blood cells, such as in autoimmune disorders or following a blood transfusion reaction.
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