A 38-year-old woman with fever, confusion, Hb 8.7 g/dL, platelets 25,000/µL, fragmented RBCs, renal failure. Most likely pathogenesis?

Correct Answer: C

Rationale: The correct answer is C: Failure to cleave von Willebrand factor multimers. This patient's presentation is consistent with thrombotic thrombocytopenic purpura (TTP), caused by a deficiency of ADAMTS13 leading to the accumulation of ultra-large von Willebrand factor multimers. This results in platelet aggregation, microthrombi formation, hemolytic anemia, and renal failure. A is incorrect because DIC typically presents with bleeding manifestations. B is incorrect as antiplatelet antibodies would not lead to the specific findings in this case. D is incorrect as verotoxin-induced endothelial damage is associated with hemolytic uremic syndrome, which typically presents with bloody diarrhea.

Correct Answer: B

Rationale: The correct answer is B: Myeloproliferative syndrome. Given the patient's symptoms (fatigue, itching, splenomegaly) and lab results (elevated Hb and platelets), it suggests an overproduction of blood cells, characteristic of myeloproliferative syndromes. Myelodysplastic syndrome (choice A) presents with cytopenias, not elevated blood counts. Paraneoplastic syndrome (choice C) is associated with malignancies, not blood disorders. Cushing syndrome (choice D) is characterized by hypercortisolism, not blood abnormalities.

Correct Answer: B

Rationale: The correct answer is B: Donor antibodies vs. recipient. Since the woman developed pulmonary edema post-transfusion, it suggests an immune reaction due to donor antibodies targeting recipient antigens, leading to inflammation and increased vascular permeability. This immune response results in fluid leakage into the lungs, causing pulmonary edema. Volume overload (A) is unlikely as the patient had pulmonary edema, not generalized edema. Recipient antibodies vs. donor (C) is incorrect as the recipient's antibodies would not cause immediate pulmonary edema post-transfusion. Bacterial contamination (D) can lead to septic reactions but is less likely to cause pulmonary edema in this context.

Correct Answer: C

Rationale: The correct answer is C because priming the transfusion set with dextrose in lactated Ringer solution can cause hemolysis of the red blood cells due to the incompatibility between the solution and PRBCs. This can lead to serious complications for the patient. Choice A is incorrect because waiting 20 minutes before starting the infusion is a standard practice to allow for compatibility checks and patient assessment. Choice B is incorrect because starting an IV with a 22-gauge catheter is appropriate for blood transfusions. Choice D is incorrect because informing the patient about potential reactions is an essential part of the consent process and patient education.

Correct Answer: D

Rationale: The correct answer is D because a patient with neutropenia and fever is at high risk for infection, which can quickly become life-threatening. Assessing and addressing this patient's condition promptly is crucial for preventing sepsis. Choices A, B, and C, although important, do not pose an immediate threat to the patient's life like neutropenia with fever does. Thalassemia with low Hb, sickle cell crisis, and emotional distress in lymphoma are important but do not require immediate assessment compared to a potentially septic patient.