Transfusion Medicine Flashcards
blood antigen vs antibody
antigen is on the blood cell, antibody is in the plasma serum
Blood group O
H antigen, anti-A/B antibodies. O-=universal blood cell donor, universal plasma recipient. can only receive O blood.
Blood group A
A antigen, anti-B serum antibody. can receive A & O blood/plasma
Blood group B
B antigen, anti-A serum antibody. Can receive B & O blood.
Blood group AB
A/B antigens, no serum antibodies. AB+=universal blood recipient, universal plasma donor. can only receive AB plasma
most common blood type?
O
where are ABO antigens located?
on all body tissues. need to be tested before any type of transplant
hemolytic disease of the newborn
Rh- mother has a Rh+ baby. At delivery, she gets exposed to Rh+ red cells of baby and begins producing Rh+ antibodies, which can cause anemia, hepato/splenomegaly, brain damage in next Rh+ baby
treatment for hemolytic disease of newborn?
Rhogam, a concentrated anti-Rh antibody.
dose Rh- mother at 28 weeks and then again at birth if newborn is Rh+. or at any point of trauma during the pregnancy
packed RBC effect
one unit raised Hgb 1-1.5 g/dL
platelet infusion effect
one unit raises count 5-10,000
crossmatch
the final checkpoint in compatibility testing for transfusions. take cells from donation bag and mix with patients serum to ensure no agglutination occurs
top 3 causes of transfusion related fatality
acute hemolytic transfusion run (usually due to clerical error), bacterial contamination of platelets, TRALI (pulmonary edema)
hemolytic transfusion rxn of ABO group
ABO antigens induce naturally occurring IgM antibodies to destroy transfused cells by fixing complement and causing intravascular hemolysis
Rh antibodies
not naturally occurring. only present if Rh- person has been exposed to the antigen through pregnancy or transfusion.
hemolytic transfusion run of Rh(D)
anti-Rh(D) is IgG and destroys transfused RBCs by reticule-endothelial phagocytosis mediated by Fc and complement receptors (extravascular hemolysis)
Coombs tests for blood type
Direct for ABO groups. IgM is large enough to bridge two RBCs.
Indirect for Rh(D0. IgG too small to bridge two RBCs, so patients serum is used and RBCs are added
hemolytic disease of the newborn caused by IgG to Rh(D)
erythroblastosis fetalis
forward typing
test patient’s RBCs for antigen by adding anti-A/B/D.
Reverse typing
test patients serum for antibodies. if anti-A is present, will agglutinate with A cells and patient is either B or O
antibody screen
tests for alloantibodies to RBC antigens. serum from patient is incubated with screening cells that have known antigens and then run through a medium with antigens. if alloantibodies are present, will not move through medium to bottom
direct antiglobulin test (DAT)
Direct Coombs Test. used to detect antibodies that are stuck to the surface of patients red blood cells.
indirect coombs test (IAT)
looks for free-flowing antibodies against certain red blood cells. tests patients serum with reagent red cells.
which blood type is most common?
O
