Transfusion Medicine I Flashcards
What are all transfusion diseases associated with?
Antigen-antibody reactions
What test will be positive with transfusion diseases?
All immune hemolytic states are associated with a positive AHG (Coombs’) Test
Isoagglutinins
- normally circulate and do not cause disease
- they are expected, “naturally-occurring”
Ex: A/B antibodies
Alloantibodies
- Ab against own species but not self
What are the most important aspects of blood transfusion?
- Specimen Identification
* Patient Identification
What is the Coombs’ test?
Detects Ig or complement proteins on red blood cells with visible RBC agglutination used to observe proteins
attached to the RBCs
Anti-Human Globulin
AHG is a serum made by purposely immunizing non-
human animals to human Ig and/or complement proteins
Indirect Antiglobulin Test
Detects Ig or complement proteins attached to RBCs in vitro. It is positive when IgG from the patients serum attaches to human RBCs which is visualized with the addition of the Coombs’ (AHG) reagent
What is blood typing?
The determination of the type of blood (A/B/O) and the Rh factor of the blood.
What is blood screening?
Test for unexpected clinically significant red blood cells antibodies
The screen is the admixture of patient’s unknown plasma with RBCs of a known phenotype.
How is blood type determined?
“Reactivity” is physically visually assessed by agglutination with admix patient’s RBCs with known typing reagents (anti-A, anti-B and anti-D)
What is the usual result of a blood screen?
They are usually negative.
What must be done with a positive blood screen result?
A positive screen result requires an antibody identification
for specificity
What is a crossmatch?
Admix patient’s plasma with blood donor’s red blood cells
When is a typing and screen done?
When the need for transfusion is remote
Ex: Surgical patients with low risk of bleeding
