This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hemolytic Anemias: Basic concepts and classification, Subject name: Pathology
[{'content': "A 56-year-old man presents with a 2-week history of fatigue. The patient's past medical history is significant for aoic and mitral valve replacement 5 months ago. A CBC shows moderate anemia with an increased reticulocyte count. Which of the following best explains the pathogenesis of anemia in this patient? \nSelect and explain. \nA. Complement-mediated hemolysis, B. Decreased blood flow, C. Direct red cell trauma, D. Sludging of erythrocytes", 'role': 'user'}, {'content': 'Answer: C \nExplanation: - Features given in the question point towards Macroangiopathic hemolytic anemia; most commonly results from direct red cell trauma d/t abnormal vascular surface (e.g., prosthetic hea valve) - Red cell fragmentation syndromes: Disorders in which erythrocytes are subjected to mechanical disruption as they circulate in the blood (intravascular hemolysis). Classified as macroangiopathic (large vessels), as in this case; microangiopathic (capillaries), according to site of hemolysis. Caused d/t alteration of endothelial surface of blood vessels or disturbances in blood flow patterns resulting in turbulence & increased shear stress.', 'role': 'assistant'}]