Blood Transfusions

Question 1

What surface antigen is A, B & O? [3]

Answer 1

A = N-acetyl-galactosamine
B = Just Galactose
O = No antigen (it's gene is a non-functional allele)

Question 2

How are blood groups inherited? [2]

Answer 2

O is recessive

A & B are dominant

Question 3

How do you decide which blood group to give when giving red cells?

Answer 3

The donor musn’t have any antigens (A or B) that the recipient doesn’t have or the host will attack the donor cells

Question 4

So who can give/receive group A red cells?

Answer 4

A can give to A or AB (as they won’t react to the donor A antigen)

The can only receive from A or O

Question 5

Who can give/receive group B red cells?

Answer 5

B can give to B or AB

Can only receive from B or O

Question 6

Who can give/receive group O red cells?

Answer 6

Can donate to anyone (as no antigens)

But can’t receive from anyone but O

Question 7

Who can give/receive group AB red cells?

Answer 7

Only donates to AB and can take from anyone

Question 8

The rules for donating fresh frozen plasma are different to red cells. How do blood groups affect FFP donation? [2]

Answer 8

With FFP donor must have all the antigens the recipient has (can also have extra.) But it won’t work if the recipient has antigens not present in the donor

Question 9

So who can give/receive group A FFP?

Answer 9

Can give to A or O

Receive from A + AB

Question 10

So who can give/receive group B FFP?

Answer 10

Can give to B or O

Can only receive from B or AB

Question 11

So who can give/receive group AB FFP?

Answer 11

Give to A, B, AB or O (so anyone)

Can receive from AB

Question 12

So who can give/receive group O FFP?

Answer 12

O can only donate to O but they can receive from anyone

Question 13

Other than the ABO blood groups the other main grouping is RhD +ve vs RhD -ve. What’s the danger of RhD? [2]

Answer 13

If RhD -ve people receive RhD +ve blood they will create Anti-D antibodies –> Transfusion reaction

Question 14

How is RhD involved in maternity? [2]

Answer 14

An RhD -ve mother can pass on anti-D antibodies to their newborn.
If they’re RhD +ve the newborn will develop haemolytic disease

Question 15

What do we test a blood donor for before using their blood? [3]

Answer 15

Behavioural screen (sex, age, travel, tattoos etc)
ABO & RhD group testing
Inf screening (HEP B,C,E, HIV & syphilis)

Question 16

Which group is the universal plasma donor?

Answer 16

AB

Question 17

Blood products: how are they obtained?

Packed red cells
Platelets
FFP
Cryoprecipitate

Answer 17

Packed red cells - obtained by centrifugation of whole blood
Platelets - pooled donation or aphaeresis
FFP - whole blood or aphaeresis
Cryoprecipitate - pooled donation

Question 18

Which blood product has highest risk of bacterial contamination?

Answer 18

Platelets: Highest risk of bacterial infection AS STORED AT ROOM TEMP

Question 19

Symptoms of Transfusion Reaction

Symptoms of mild transfusion reaction

Answer 19

Urticaria
Flushing
Temperature rise of <2oC

Question 20

Symptoms of Transfusion Reaction

Moderate symptoms

Answer 20

Wheezing
Angioedema
Hypotension
Temperature rise of >2oC

Question 21

Symptoms of Transfusion Reaction

Severe Symptoms:

Answer 21

Hypotension with evidence of shock
Respiratory compromise such as stridor or anaphylaxis
Temperature rise of >2oC

Question 22

Management of Transfusion Reaction

Mild

Answer 22

Paracetamol
Antihistamines

Question 23

Management of Transfusion Reaction

Moderate

Answer 23

Stop transfusion immediately
Assess whether pyrexia is in keeping with the patient’s clinical history
If not, send unit of blood for culture and take blood cultures from the patient

Question 24

Management of Transfusion Reaction

Severe

Answer 24

Acute management of airway, breathing, and circulation
Specific measures such as adrenaline IM 1:1000 are needed if there is evidence of anaphylaxis
Same as for moderate symptoms

Question 25

Acute haemolytic transfusion reactions, e.g. ABO blood group incompatibility

Immunology pathogenesis, timing of reaction

Answer 25

Happens immediately. IgM mediated; intravascular haemolysis secondary to activation of complement.

Question 26

Delayed haemolytic transfusion reactions

Immunology pathogenesis, timing of reaction

Answer 26

Between 1-14 days after transfusion. IgG mediated; extravascular haemolysis;
due to the development of clinically significant alloantibodies which may not have been detected during pre- transfusion testing.

Question 27

Non haemolytic allergic reactions vs febrile non-haemolytic reactions

Difference in pathogenesis and prevention methods

Answer 27

Non haemolytic allergic reactions - pruritus, urticaria. occur due to reactions to plasma protein and are prevented by leucodepletion.
Febrile non-haemolytic reactions occur o antibodies against human leucocyte antigens (HLA). Can be prevented by pre-medication with paracetamol.

Question 28

TACO - Transfusion associated circulatory overload

Signs, risk factors, management

Answer 28

• Excessive rate of transfusion, pre-existing heart failure
• Pulmonary oedema, hypertension
• Use of diuretics; slowing the rate of transfusion; reassessing clinical need for each subsequent unit of transfusion.