Theme 2: Lecture 8 - Principles of blood transfusion

Question 1

What is the fundamental problem with blood transfusion

Answer 1

• Red cells have antigens on their surface
• Human plasma may contain antibodies to these antigens
• These can cause reactions - sometimes fatal

Question 2

Agglutinins

Answer 2

Naturally occurring pentameric IgM antibodies in the plasma

Question 3

What does transfusion of ABO incompatible blood cause

Answer 3

intravascular lysis (red blood cells rupture)

Question 4

What can intravascular lysis due to transfusion of incompatible blood cause

Answer 4

• shock, hypotension, tachycardia
• renal failure, loin pain, haemoglobinuria
• disseminated intravascular coagulation
• death

Question 5

haemoglobinuria

Answer 5

presence of excess haemoglobin in the blood

Question 6

Blood group A

Answer 6

If you belong to the blood group A, you have A antigens on the surface of your red blood cells and B antibodies in your blood plasma.

Question 7

Blood group B

Answer 7

If you belong to the blood group B, you have B antigens on the surface of your red blood cells and A antibodies in your blood plasma

Question 8

Blood group AB

Answer 8

If you belong to the blood group AB, you have both A and B antigens on the surface of your red blood cells and no A or B antibodies at all in your blood plasma.

Question 9

Blood group O

Answer 9

If you belong to the blood group 0 (null), you have neither A or B antigens on the surface of your red blood cells but you have both A and B antibodies in your blood plasma.

Question 10

What is cross matching by forward grouping

Answer 10

Determining what antigens are present on the RBCs by mixing a patient’s RBCs with known anti serum

Question 11

What is cross matching by reverse grouping

Answer 11

Determines what antibodies are present by mixing patient’s plasma with known RBCs

Question 12

Who can blood group AB give blood to

Answer 12

Blood group AB

Question 13

Who can blood group AB receive blood from

Answer 13

AB, A, B, O

Question 14

Who can blood group A give blood to

Answer 14

A and AB

Question 15

Who can blood group A receive blood from

Answer 15

A and O

Question 16

Who can blood group B give blood to

Answer 16

B and AB

Question 17

Who can blood group B receive blood from

Answer 17

B and O

Question 18

Who can blood group O give blood to

Answer 18

AB, A, B, O

Question 19

Who can blood group O receive blood from

Answer 19

O

Question 20

% of people with blood group O in the UK

Answer 20

46%

Question 21

% of people with blood group A in the UK

Answer 21

42%

Question 22

% of people with blood group B in the UK

Answer 22

9%

Question 23

% of people with blood group AB in the UK

Answer 23

3%

Question 24

What does the lad do when you send a blood sample

Answer 24

• Test the ABO group of red cells

- Screen for atypical antibodies

Question 25

What are atypical antibodies

Answer 25

- These arise due to sensitisation with foreign red cell antigens - Atypical antibodies can cause blood transfusion reactions if the patient is transfused with incompatible blood in the future

Question 26

What causes atypical antibodies

Answer 26

- previous blood transfusion | - pregnancy

Question 27

Anti-globulin or Coombs test

Answer 27

It uses anti-immunoglobulin antibody to agglutinate red cells

Question 28

What are the two types of anti globulin or Coombs test

Answer 28

- Direct antiglobulin test (DAT) | - Indirect antiglobulin test (IAT)

Question 29

What does the DAT tell us

Answer 29

The DAT tells us if red cells are coated with antibody

Question 30

When is the DAT positive

Answer 30

- It is positive after a transfusion reaction and in HDN | - It is also positive in autoimmune haemolytic anaemia

Question 31

IAT

Answer 31

- The IAT is used in the lab for testing blood group antigens - It can tell us if a patient is positive for Rhesus and other blood groups

Question 32

Can Rhesus positive people develop antibodies

Answer 32

No

Question 33

When can Rhesus negative people develop antibodies

Answer 33

- they are transfused with Rh pos blood | - pregnant with a Rh pos baby

Question 34

What antibody is generated in Rhesus sensitisation

Answer 34

IgG type antibodies

Question 35

What is Rhesus sensitisation

Answer 35

When Rhesus negative people develop antibodies

Question 36

Haemolytic disease of the newborn (HDN)

Answer 36

If a mother, who is Rh neg is pregnant with an Rh pos fetus, she may produce antibodies that can cross the placenta and harm the baby

Question 37

Can a Rh negative person who develops Rh antibodies be given Rh positive blood

Answer 37

No

Question 38

Which antigens does the Rhesus system comprise of

Answer 38

C, D and E (only need to know D)

Question 39

What can HDN cause in the baby

Answer 39

- Anaemia - Jaundice - Kernicterus

Question 40

Kernicterus

Answer 40

brain damage due to high levels of bilirubin in the blood

Question 41

How is HDN prevented

Answer 41

- Rh-ve women (15%) receive anti-D antibody i.m. injection at 28 and 34 weeks to prevent sensitisation - Baby tested at birth and if Rh+ve, mother receives further anti-D until Kleihauer test (foetal cells) becomes negative - If already sensitised, then the foetus requires monitoring via trans-cranial Doppler scan and may require intra-uterine transfusions if signs of anaemia

Question 42

What is in a bag of donated blood

Answer 42

- Red cells - Buffy coat (white cells, platelets) - Plasma (albumin, gamma globulins, coagulation factors) - Water, electrolytes, additives

Question 43

What is the process that blood goes through to be separated into its different parts

Answer 43

Fractionation

Question 44

Apheresis

Answer 44

A medical procedure that involves removing whole blood from a donor or patient and separating the blood into individual components so that one particular component can be removed. The remaining blood components then are re-introduced back into the bloodstream of the patient or donor.

Question 45

When do you give a blood transfusion

Answer 45

- Severe acute blood loss - Elective surgery associated with significant blood loss - Medical transfusions (cancer, chemotherapy, renal failure) - Anaemia

Question 46

When do you give a blood transfusion in anaemia

Answer 46

- Only for symptomatic anaemia or if refractory to haematinic replacement - Bone marrow failure e.g., myelodysplasia or aplastic anaemia - Haemoglobinopathy - thalassaemia major and sickle cell disease

Question 47

Cryoprecipitate

Answer 47

plasma but enriched with fibrinogen

Question 48

What type of transfusion is cell salvage

Answer 48

blood lost during operation is reinfused into the patient (rarely done)

Question 49

What is an autologous transfusion

Answer 49

store blood from somebody to be given back to them at a later date (very rarely done)

Question 50

What other transfusion reactions are there (excluding transfusion of ABO incompatible blood)

Answer 50

- Febrile non-haemolytic reactions - Fluid overload - Anaphylaxis and severe allergic reactions - Minor allergic reactions - Delayed transfusion reactions - TRALI (transfusion related acute lung injury

Question 51

What are the broad transfusion transmitted infections that you could get

Answer 51

- Bacterial infections - Viral infections - Malaria - vCJD

Question 52

What are the bacterial infections you could get from blood transfusions

Answer 52

- syphilis - pyogenic infections - contamination infections (pseudomonas)

Question 53

What are the viral infections you could get from blood transfusions

Answer 53

- hepatitis (B,C) - HIV - Others - HTLV (Human T-lymphotropic virus), CMV - Emerging - West Nile virus

Question 54

Haemosiderosis

Answer 54

iron overload

Question 55

How is iron overload treated

Answer 55

by iron chelation

Question 56

What can happen if you transfuse too quickly

Answer 56

fluid overload

Question 57

What can fluid overload cause

Answer 57

acute pulmonary oedema

Question 58

Frusemide

Answer 58

A diuretic drug

Question 59

How is fluid overload treated

Answer 59

with diuretics to remove fluid