Blood transfusion 1

Question 1

1. Describe how the consequences of rhesus incompatibility are different from ABO incompatibility in a patient receiving a blood transfusion

Answer 1

ABO – immediate haemolytic transfusion reaction (can be fatal)
Rhesus – delayed haemolytic transfusion reaction

Question 2

3. What is a dangerous consequence of rhesus incompatibility in a pregnant woman?

Answer 2

Haemolytic disease of the newborn

Question 3

4. How is the patient’s blood group tested?

Answer 3

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

Question 4

5. How can the types of red blood cell antibodies in the patient’s serum be identified?

Answer 4

Known A and B group red blood cells are mixed with the patient’s plasma (which contains IgM antibodies)

Question 5

6. What must be done before every transfusion?

Answer 5

Group and screen

Question 6

7. Describe how the antibody screen of a patient’s plasma works.

Answer 6

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

Question 7

8. What labels are included on issued blood?

Answer 7

ABO and D type
Kell
Other Rh antigens

Question 8

9. Which patient group should receive K negative blood?

Answer 8

Women of childbearing potential

Question 9

10. What is a full crossmatch?

Answer 9

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

Question 10

11. What is an immediate spin?

Answer 10

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

Question 11

12. What is an electronic crossmatch?

Answer 11

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

Question 12

13. How long do red cells survive in storage?

Answer 12

35 days in 4 degrees

Question 13

14. How soon after leaving storage do red cells need to be transfused?

Answer 13

4 hours

NOTE: red cells can be returned to the fridge within 30 mins of leaving storage

Question 14

15. Describe how platelets are cross-matched.

Answer 14

They do NOT need cross-matching because the antigens are weakly expressed

Question 15

16. Which antigens are important when considering plasma transfusion?

Answer 15

Only ABO

Question 16

17. If group O blood is given to A, B or AB patients, what precaution should you take?

Answer 16

Use high titre negative blood (i.e. plasma contains low levels of anti-A and anti-B antibodies)

Question 17

18. What is the universal donor for:
    a. Red blood cells
    b. Plasma

Answer 17

a. Red blood cells
O-
b. Plasma
AB (contains no anti-A or anti-B antibodies)

Question 18

20. What should you do if a patient receiving a platelet transfusion develops a fever?

Answer 18

Stop the platelets and take blood cultures

Platelets should be sent back to the lab for microbiological testing

Question 19

21. If a patient develops a reaction to a plasma transfusion, what is the most likely cause?

Answer 19

Allergic reaction

NOTE: plasma is frozen so it is unlikely to get contaminated by bacteria

Question 20

List some indications for transfusion.

Answer 20

Major blood loss
Peri-operative care
Post-chemotherapy
Symptomatic anaemia

Question 21

25. List some methods of transfusing your own blood.

Answer 21

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

Question 22

27. Which patient groups require CMV-negative blood?

For intra-uterine and neonatal transfusions

Answer 22

Elective transfusion in pregnancy

Question 23

28. Which patients require irradiated blood and why?

Answer 23

Highly immunosuppressed patients
These patients cannot destroy donor lymphocytes and the presence of lymphocytes in donated blood can cause graft-versus-host disease

Question 24

29. Which patients require washed blood?

Answer 24

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

Question 25

30. List some indications for platelet transfusions.

Answer 25

Massive transfusion
Prevent bleeding (post-chemotherapy)
Prevent bleeding (surgery) 
Platelet dysfunction

Question 26

31. List some contraindications for platelet transfusion.

Answer 26

Heparin-induced thrombocytopaenia

TTP

Question 27

33. List some indications for FFP transfusion.

Answer 27

Massive transfusion
DIC
Liver disease

Question 28

37. What is the best option for the reversal of warfarin?

Answer 28

Prothrombin complex concentrate (contains 2, 7, 9 and 10)