Coagulation Disorders USMLE Step 1 Practice Question
A 52-year-old woman with a history of iron deficiency anemia receives a packed red blood cell transfusion for gastrointestinal bleeding. Minutes into the transfusion, she develops fever (38.9°C), flank pain, hypotension (BP 88/52), tachycardia (HR 118), and dark urine. Laboratory studies show elevated creatinine (2.1 mg/dL), decreased haptoglobin, and elevated indirect bilirubin. Urinalysis reveals hemoglobinuria without red blood cells. She denies prior transfusions. Which of the following is the most likely cause of this reaction?
Answer choices
- ARecipient antibodies against donor ABO antigens causing complement-mediated hemolysisCorrect answer
- BDonor lymphocytes attacking recipient tissues
- CDelayed formation of anti-Rh antibodies
- DCytokine release from donor leukocytes during storage
- EPreformed IgE against donor plasma proteins
- FRecipient antibodies against donor HLA antigens causing immune complex deposition in the lungs
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