Final answer:
The indirect Coombs' test or indirect antiglobulin test (IAT) is used to detect antibodies against red blood cell antigens in a patient's serum, which are not the A and B antigens. This test is crucial for evaluating the risk of hemolytic disease in newborns and ensuring the safety of blood transfusions. The presence of such antibodies can be indicative of various medical conditions.
Step-by-step explanation:
Indirect Coombs' Test: Understanding the Process
The indirect Coombs' test, also known as the indirect antiglobulin test (IAT), is a laboratory procedure used to screen for the presence of antibodies against red blood cell (RBC) antigens in a patient's serum. These antibodies are not the common A and B antigens associated with blood types but rather other antigens that could trigger adverse reactions such as hemolytic disease of the newborn or complications during blood transfusions. To perform the test, a few drops of the patient's blood serum are mixed with a Coombs' reagent, which contains antihuman antibodies. If antibodies against RBC antigens are present in the serum, they will bind to the reagent, indicating a positive result. The indirect Coombs' test is particularly important for pregnant women and in pre-transfusion testing.
The presence of antibodies in the serum can lead to conditions such as hemolytic transfusion reactions, autoimmune hemolytic anemia, and may also play a role in reactions to infections, certain drugs, and even some cancers. While the indirect Coombs' test focusses on unbound antibodies in vitro, its counterpart, the direct Coombs' test, detects antibodies or complement proteins already adhere to red blood cells in vivo.