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MBBS QUESTION #10228
Question 1
A patient receiving a transfusion of ABO-incompatible blood develops fever, flank pain, and hemoglobinuria within minutes. This acute hemolytic transfusion reaction is primarily mediated by:
  • Pre-formed recipient IgM antibodies binding donor RBC antigens and activating complement, causing intravascular hemolysis✔️
  • A delayed T-cell mediated response developing over several days
  • Bacterial contamination of the transfused unit
  • Simple volume overload from the transfusion
Correct Answer Explanation
ABO antibodies are naturally occurring IgM antibodies that, upon encountering mismatched donor red cells, rapidly fix complement and cause intravascular hemolysis, releasing free hemoglobin (hemoglobinuria) and triggering fever, flank/back pain, and potentially disseminated intravascular coagulation and renal failure — a medical emergency requiring immediate transfusion cessation.