Question:medium
Which of the following investigations should be done immediately to best confirm a mismatched (non-matched) blood transfusion reaction?
Which of the following investigations should be done immediately to best confirm a mismatched (non-matched) blood transfusion reaction?
Show Hint
You need the test for antibody already bound to red cells in vivo.
Updated On: Jun 24, 2026
- Indirect Coombs test
- Direct Coombs test
- Antibody in the patient's serum
- Antibody in the donor serum
Show Solution
The Correct Option is B
Solution and Explanation
Think about where the action is during an acute mismatched transfusion. The patient's own antibodies coat the donor red cells inside the body, so the evidence of the reaction is sitting ON the red cells in the circulating blood.
The test that looks directly at antibody stuck to red cells is the direct antiglobulin test, the Direct Coombs. It needs no incubation step and gives a quick positive when donor cells are antibody-coated, so it is the best immediate confirmation of an in-vivo haemolytic reaction.
The indirect Coombs works the other way round, detecting free antibody in serum, which is what we do before transfusion during crossmatching, not to confirm a reaction that has already started. Hunting for antibody in patient or donor serum is part of the later investigation to find which antigen was responsible, but it is slower and not the first confirmatory step. So the right immediate choice is the direct test.
\[\boxed{\text{B. Direct Coombs test}}\]
The test that looks directly at antibody stuck to red cells is the direct antiglobulin test, the Direct Coombs. It needs no incubation step and gives a quick positive when donor cells are antibody-coated, so it is the best immediate confirmation of an in-vivo haemolytic reaction.
The indirect Coombs works the other way round, detecting free antibody in serum, which is what we do before transfusion during crossmatching, not to confirm a reaction that has already started. Hunting for antibody in patient or donor serum is part of the later investigation to find which antigen was responsible, but it is slower and not the first confirmatory step. So the right immediate choice is the direct test.
\[\boxed{\text{B. Direct Coombs test}}\]
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