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NBME 22 Answers

nbme22/Block 2/Question#9

A 26-year-old woman develops hypotension and ...

Antibody, complement C5-9

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Diagnosis: Acute Hemolytic Transfusion Reaction


Type II hypersensitivity reaction. Intravascular hemolysis (ABO blood group incompatibility) or extravascular hemolysis (host antibody reaction against foreign antigen on donor RBCs).


Fever, hypotension, tachypnea, tachycardia, flank pain, hemoglobinuria (intravascular hemolysis), jaundice (extravascular). Within 1 hour.

This is acute hemolytic transfusion reaction, I believe. Type II HSR so she’s forming antibodies against the ABO groups on the blood cells. Complement is induced by antibodies.

kfratta1  But with hypotension in the stem I thought more of anaphylaxis due to IgA def. Why would a T2 HSR give you hypotension? +1  
2ndmedschool  I think the hemoglobinuria is the key. As I’m looking at it it seems that anaphylaxis would cause hypotension, urticaria, itching, wheezing. ABO incompatibility is the only one that mentions hemoglobinuria. +2  
hyperfukus  abo incompatibility and rh incompatibility with mom blood rxns are gonna TYPE 2 no matter what it looks like +