Blood transfusion 1 Flashcards
- Describe how the consequences of rhesus incompatibility are different from ABO incompatibility in a patient receiving a blood transfusion
ABO – immediate haemolytic transfusion reaction (can be fatal)
Rhesus – delayed haemolytic transfusion reaction
- What is a dangerous consequence of rhesus incompatibility in a pregnant woman?
Haemolytic disease of the newborn
- How is the patient’s blood group tested?
Anti-A, anti-B and anti-D reagents are mixed with the patient’s red blood cells
NOTE: a positive result means that the red cells will float to the top of the vial
- How can the types of red blood cell antibodies in the patient’s serum be identified?
Known A and B group red blood cells are mixed with the patient’s plasma (which contains IgM antibodies)
- What must be done before every transfusion?
Group and screen
- Describe how the antibody screen of a patient’s plasma works.
Conducted using the indirect antiglobulin test (IAT)
2 or 3 reagent red blood cells are used which contain all the important red cell antigens
The patient’s serum is incubated with these screening cells
Anti-human immunoglobulin is added to the solution which allows bridging of red cells that are coated with IgG
This results in the formation of a visible clump
This is a group and screen
- What labels are included on issued blood?
ABO and D type
Kell
Other Rh antigens
- Which patient group should receive K negative blood?
Women of childbearing potential
- What is a full crossmatch?
Uses indirect antiglobulin test
Patients plasma is incubated with DONOR red cells at 37 degrees for 30-40 mins
Anti-human immunoglobulin is added to allow cross-linking of antibodies
Formation of a clump would suggest that antibodies against donor red cell antigens are present in the patient’s plasma
- What is an immediate spin?
Incubate patient’s plasma and donor red cells for 5 mins and spin
This will only detect ABO incompatibility
Used in emergency situations
IgM anti-A or anti-B will bind to donor RBCs, fix complement and lyse cells
- What is an electronic crossmatch?
Also called electronic issue (EI)
Compatibility is determined by an IT system without physical testing of donor cells against plasma
NOTE: this is quick, requires fewer staff and allows better stock management
- How long do red cells survive in storage?
35 days in 4 degrees
- How soon after leaving storage do red cells need to be transfused?
4 hours
NOTE: red cells can be returned to the fridge within 30 mins of leaving storage
- Describe how platelets are cross-matched.
They do NOT need cross-matching because the antigens are weakly expressed
- Which antigens are important when considering plasma transfusion?
Only ABO
- If group O blood is given to A, B or AB patients, what precaution should you take?
Use high titre negative blood (i.e. plasma contains low levels of anti-A and anti-B antibodies)
- What is the universal donor for:
a. Red blood cells
b. Plasma
a. Red blood cells
O-
b. Plasma
AB (contains no anti-A or anti-B antibodies)
- What should you do if a patient receiving a platelet transfusion develops a fever?
Stop the platelets and take blood cultures
Platelets should be sent back to the lab for microbiological testing
- If a patient develops a reaction to a plasma transfusion, what is the most likely cause?
Allergic reaction
NOTE: plasma is frozen so it is unlikely to get contaminated by bacteria
List some indications for transfusion.
Major blood loss
Peri-operative care
Post-chemotherapy
Symptomatic anaemia
- List some methods of transfusing your own blood.
Pre-operative autologous deposit (not available in the UK)
Intra-operative cell salvage (blood is collected during surgery, centrifuged, filtered and reinfused)
Post-operative cell salvage (blood that is lost post-operative is collected via a wound drain, filtered and re-infused – usually for orthopaedic operations)
NOTE: all coagulation factors and platelets are removed in cell salvage
- Which patient groups require CMV-negative blood?
For intra-uterine and neonatal transfusions
Elective transfusion in pregnancy
- Which patients require irradiated blood and why?
Highly immunosuppressed patients
These patients cannot destroy donor lymphocytes and the presence of lymphocytes in donated blood can cause graft-versus-host disease
- Which patients require washed blood?
Patients who have severe allergic reactions to donors’ plasma proteins
This takes 4 hours so must be requested in advance
NOTE: IgA deficient patients are more likely to need washed blood
