Transfusion Medicine Flashcards
Compare the antibody response between ABO and non-ABO antigens.
ABO incompatibility leads to acute hemolytic transfusion reaction, which is brisk, and releases free hemoglobin (anti-A and anti-B strongly activate complement) non-ABO incompatibility leads to delated hemolytic transfusion reaction
Screen for non-ABO antigen is done with which lab test?
indirect antibody test (coombs reaction) where patient plasma is mixed with 2-3 reagent RBC and anti-human globulin (to bridge gap and allow any agglutination- anti IgG directed against Fc of IgG)
Most non-ABO clinically significant antibodies are ____.
IgG
Agglutination in the non-ABO screen should be followed up with what testing?
antibody panel is done to find antibody specificity
Contrast warm reactive and cold reactive antibodies.
Warm reactive: IgG, require exposure, hemolytic disease of newborn, hemolytic transfusion reactions and are “significant” Cold reactive: IgM, naturally occurring, no HDN, no HTRs “insignificant (ABO being the exception)
What is crossmatch?
determines if patient plasma is compatible with specific RBC unit (test by mixing plasma with specific RBC unit)
What are the earliest signs of an acute hemolytic transfusion reaction?
fever and chills, always stop the transfusion to determine the actual cause by calling the blood bank
What is the most fatal consequence of AHTR?
kidneys are at highest risk, use bolus saline and diuretics to keep the kidneys working remember AHTR is dose-dependent
What is the molecular cause of hemolysis in AHTR?
complement activation to C9 causes MAC formation leading to brisk intravascular hemolysis hemolysis leading to increased free Hb leads to depletion of NO and vasoconstriction (kidneys most vulnerable)
Why might you get a “false” negative in testing delayed hemolytic transfusion reaction?
after initial rise in antibodies, antibodies can fall below detectable levels but still go on to cause a secondary response to antigen with significant antibody levels (there may be a long time between testing and first exposure and antibodies have waned)
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