This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Direct Coombs test is positive in all the following except: 
Select and explain. 
A. Hemolytic anemia due to transfusion, B. Hemolytic anemia due to transfusion, C. Aplastic anemia, D. Drug-induced AIHA
C: Aplastic anemia
Answer: C: Aplastic anemia 
Explanation: Ans: C. Aplastic anemia(Ref: Robbins 9/e p643).Direct Coomb's test is negative in aplastic anemia.Direct Coomb's testAlso known as direct antiglobulin testdegDetect antibodies of complement bound to RBC surfaceantigens in vivodeg.It is used for:Immune-mediated hemolytic anemia degHemolytic disease of the newborndegRh D-hemolytic disease of the newborn degABO hemolytic disease of the newborndegDrug-induced immune-mediated hemolysisdegMismatch transfusion reactiondeg.