1. A patient develops sudden back pain, fever, and red urine 10 minutes into the transfusion of a unit of RBCs. Which one of the following should be on the top of your differential diagnosis?

2. A stable 35-year-old white male patient develops urticaria and acute dyspnea requiring emergent intubation 15 minutes into the transfusion of 1 U fresh frozen plasma. His pretransfusion vital signs are heart rate (HR), 70 beats/min; respiratory rate (RR), 18/min; blood pressure (BP), 125/80 mm Hg; temperature (T), 36.8°C; and O2 saturation, 99% on room air. Postreaction vital signs are HR, 130 beats/min; RR, 30/min; BP, 90/50 mm Hg; T, 36.8°C; and O2 saturation, 75% on room air. He had a similar reaction to plasma in the past, also requiring intubation. Which of the following should be at the top of your differential diagnosis as a cause of the transfusion reaction?

3. According to expert opinion, which one of the following is the pathophysiology of a febrile nonhemolytic transfusion reaction (FNHTR) after transfusion of a prestorage leukoreduced blood component?

4. Which one of the following is part of the diagnostic criteria for transfusion-related acute lung injury (TRALI)?