Blood group typing for transfusion (cells & products) Flashcards
1
Q
What anaemias are treatable by transfusion (11)
A
- Trauma
- Surgery
- GIT bleeding (ulcer; NSAIDs)
- Reproductive - Menorrhea, pregnancy, miscarriage, birth
- Haemolytic disorder
- G6PD-haemolysis
- HDNB
- Haemoglobinaemias
- Sickle Cell Disease, SCD
- Thalassemia
- Malignancy/chemotherapy
2
Q
What anaemias are treatable by supplements (4)
A
- Hematinic deficiencies
- iron deficiencies
- B12 deficiencies
- folate deficiencies
3
Q
What is used to remove excess iron from multiple transfusions
A
Chelation
4
Q
What is the immunological basis of compatibility for transfusion (2)
A
- Erythrocyte antigens
- plasma antibodies
5
Q
What are the common blood types based on ABO & Rh (+/-) (D-antigen) (5)
A
- A
- B
- AB
- O
- with +/− or Null denoting RhD status
6
Q
What are the rare (>200) but can complicate transfusion (reactions) blood types (4)
A
- Oh
- Anti-D
- Anti-c (‘little c’)
- anti-K (Kell)
7
Q
How is enzymatic formation of H; B & A antigens achieved (5)
A
- RBC membrane proteins “derive” from the H antigen of the O-group, via enzymatic PTModification that alters antigenicity:
- Fucosyl transferase 1 (FUT1) adds Fucose to D-Galactose to create the H-antigen of O-group
- A/B-antigens enzymatically derived from H-antigen, if relevant ABH transferases present on Chromosome 9:
- The A gene codes for N-acetylgalactosaminyl transferase to convert H to A.
- The B gene codes for D-galactosyl transferase to convert H to B.
8
Q
What is agglutination (2)
A
- If an antibody in plasma binds to antigens on a red cell it causes agglutination
- This is different from “coagulation” due to soluble blood factors
9
Q
How do blood groups affect donation (4)
A
- Group O can donate red blood cells to anybody. It’s the universal donor.
- Group A can donate red blood cells to A’s and B’s.
- Group B can donate red blood cells to B’s and AB’s
- Group AB can donate to other AB’s, but can receive from all others
10
Q
Who is the “universal” blood (cell) donor? (3)
A
- Those belonging to the O- blood group are calleduniversal blood [cell] donors.
- The red blood cells of a universal blood [cell] donor may be transfused to anyone regardless of their [Major] blood type.
- O Rh- is considered “universal”.
11
Q
Who is the “universal” plasma donor? (3)
A
- Those belonging to the AB blood group (positive or negative) are calleduniversal plasma donors.
- The plasma of those belonging to the AB blood group may be transfused to anyone regardless of blood type.
- AB Rh+ is considered “universal”.
12
Q
What is the significance of plasma antibodies (5)
A
- Antibodies are high titer & avidity; react at 37oC
- Antibodies activate complement/other reactions:
- Antibodies activate haemolysis (anaemia)
- Antibodies activate cytokine disturbance (shock, organ failure)
- Antibodies activate immune precipitation (kidney failure)
13
Q
What is the significance of antigens in blood groups (2)
A
- Antigens present on red cells in large amounts
- Knowledge of Ag and Ab enables matching of donor blood to the recipient – increasing the chance of success
14
Q
What is the significance of adverse transfusion reactions (4)
A
- There have been reports of deaths after transfusion of 30ml of ABO-incompatible blood.
- More usually around 200ml will be enough to cause a severe reaction
- This is why patients should be closely monitored for the first 15 minutes of the transfusion/regularly
- Delayed transfusion reactions beyond 24hr are also possible
15
Q
Why can’t babies be reverse-typed (2)
A
- Antibodies present in baby serum have crossed the placenta from the mother.
- Babies do not make detectable antibody in their serum until 3 to 6 months of age.
16
Q
What is the secretor gene (2)
A
- 80% of the Caucasian population carry the secretor gene
- This is blood group antigens secreted in saliva, semen etc
17
Q
What is the secretor status (4)
A
- Blood Group A Secretor-saliva = H-antigens & A-Ags
- Blood Group B Secretor-saliva = H-antigens & B-Ags
- Blood Group O Secretor-saliva = H-antigens
- Blood Group AB Secretor-saliva = H-, A- & B-Ags
18
Q
What is the rhesus (Rh) blood group (2)
A
- Second only to ABO system for rbc antigenicity
- Three antigens controlled by two genes
19
Q
What are the two genes controlling the Rh bloog group antigens (5)
A
- one gene for Rhesus(D) antigen
- the other gene (RHCE) controls Rh(CE)
- Most often Rhesus positive – meaning the individual types Rh (D) positive
- Individuals may also be C or c and E or e
- So a very complex Rh profile can be present; driving need for compatibility tests
20
Q
What is haemolytic disease of the newborn
A
Antibodies to RhD are only generated in Rh- individuals through Transfusion reaction or Foetal-maternal contamination in pregnancy = Haemolytic Disease of the Newborn, HDNB
21
Q
What is the prophylactic use of Anti-D
A
Given to Rh (D)-negative mothers following birth of first Rh (D)-positive child. This destroys circulating Rh (D)-positive red cells within the mother’s circulation, thereby preventing alloimmunisation
22
Q
What tests are there to avoid blood grouping reaction
A
immunological matching prior to transfusion
23
Q
What tests is there for blood typing of major ABO/Rh antigens (2)
A
- Forward agglutinin test: cellular antigens
- Reverse agglutinin test: concordance of serum antibodies
24
Q
What tests are there for recipient (serum Ab) incompatibility to donor rbc prior to transfusion & post-transfusion immune-haemolytic Ig testing (2)
A
- Indirect Antiglobulin/Coombs Test, IAT: detects risk of lysis
- Direct Antiglobulin/Coombs Test, DAT: detects acquired lysis
25
What are IAT and DAT tests (4)
1. very important techniques for detecting haemolytic risk/cause:
2. IAT - The potential for creating incompatibility antibodies by immune reactions to transfusion
3. DAT - The existence of alloantibodies previously induced by transfusion or autoantibodies.
4. Identifying the haemolytic antibody – depends upon a screen using commercially typed cells
26
What group of people are able to donate blood (3)
1. Most people between the ages of 17 and 66
2. weigh over 50kg (7st 12lb)
3. have a good level of general health
27
When should people never donate blood (6)
1. had HIV
2. had hepatitis C
3. had syphilis
4. had the human t-lymphotropic virus (HTLV)
5. injected yourself with drugs
6. worked as a commercial sex worker
28
What screening of blood for markers of infectious diseases is there (3)
1. Antigens of infectious pathogens
2. Antibodies to infectious pathogens
3. Nuclear material of infectious pathogens (NAT [nucleic acid amplification test])
29
What are the blood products (4)
1. Red blood cells - carry oxygen to the body’s organs and tissue.
2. Platelets - small blood cells that initiate blood clotting - control bleeding.
3. Plasma - 90% water; 55% of blood vol. Pale yellow mixture of water, salts & proteins, including solvable clotting factors; Fractionable Igs
4. Cryoprecipitated Antihaemophilic Factor - a frozen blood product from plasma - a source of fibrinogen and other clotting factors.
30
How are platelets stored and obtained (3)
1. must be used within five (5) days of collection
2. blood donations are especially needed around 3-day weekends.
3. Obtained by Aphersis to separate out one particular constituent and return the remainder to the circulation.
31
How are red blood cells stored
Must be used within 42 days
32
How is plasma stored
Can be frozen and used for up to a year
33
How is leukoreduced blood products treated
reduces transfusion reactions and tissue type rejection through immune sensitising to HLA
34
How is the risk of serious side effects from blood transfusions kept low (2)
1. X-matching of Recipient/Donor bloods for blood group compatibility.
2. Regular monitoring during transfusion for possible reactions
35
What are the immunological risks associated with blood transfusion (4)
1. Allergic reaction
2. Anaphylaxis – vascular shock – multiple organ failure…
3. Lung injury - Transfusion-related acute lung injury (TRALI)
4. Haemolytic transfusion reaction (HTR)
36
What is the haemodynamic risk associated with blood transfusion
fluid overload
37
What are the infection risks associated with blood transfusion (4)
1. Bacterially contaminated blood
2. Viral contaminated blood
3. Variant Creutzfeldt-Jakob disease (vCJD)
4. Malaria possible as a febrile illness post-transfusion
38
What are the main symptoms of acute haemolytic reaction (13)
1. chills
2. fever
3. hypotension
4. uncontrollable bleeding
5. heat sensation
6. lumbar pain
7. increased heart rate
8. chest constricting pain
9. urinary haemoglobinuria
10. urinary hyperbilirubinemia
11. urinary haemolysis
12. urinary jaundice
13. urinary excretion of Hb and metabolites
39
What objections may there be to blood transfusions (2)
1. May arise for personal, medical, or religious reasons (e.g. Jehovah's Witnesses)
2. Regarding the <18 years - Parental responsibility which can be challenged
