Transfusion

Question 1

What is the minimum criteria required in healthy, volunteer donors?

Answer 1

Hb 135g/L men

Hb 125g/L women

Weight 50kg

Question 2

What is checked to further improve the safety of the blood?

Answer 2

Donor health check

Contact details if becomes unwell post donation

Question 3

What is involved in blood processing and testing?

Answer 3

Bag of whole blood centrifuged to separate into component parts

Samples undergo microbiological testing HIV, Hep B, Hep C, Hep E, HTLV, Syphilis

Red cells- stored at 4°C for 35 days

FFP (fresh frozen plasma) - stored -30°C for 3 years

Platelets- stored 22°C for 7 days with agitation

Question 4

What are the products available from a blood donation?

Answer 4

Blood components
Red cells, FFP, platelets, cryoprecipitate

Blood products
Anti-D immunoglobulin, prothrombin complex concentrate

Blood products from pharmacy
Iv immunoglobulin, human albumin, specific Ig

Question 5

How are blood groups influenced?

Answer 5

Membranes of red cells contains many different antigens.

The antigens that are expressed is determined by which blood group antigen genes we inherit from our parents.

38 different families of blood group systems have been identified.

Question 6

What chromosome is the ABO gene located on?

Answer 6

Chromosome 9

Question 7

What is phenotype vs genotype?

Answer 7

• Phenotype - which antigens are detected
• Genotype - which genes are present

Question 8

What is Landsteiner’s law?

Answer 8

When an individual lacks A or B antigen the corresponding antibody is produced in their plasma

Naturally occurring antibodies cause haemolysis of red cells
expressing the specific antigen

Makes ABO the most clinically significant blood group system

Question 9

What blood type is the most compatible?

Answer 9

Blood group O

Donor blood O is compatible with recipient type O blood and groups A, B and Ab as well.

Question 10

Donor group A is compatible with recipient group B. True/false?

Answer 10

False

Donor group A only compatible with recipient types A and AB.

Donor group B only compatible with recipient types B and AB.

Question 11

Donor group AB is only compatible with recipient group AB. True/false?

Answer 11

True

Question 12

What % of the population are RhD positive?

Answer 12

85%

Question 13

What alleles are inherited for RhD?

Answer 13

2 alleles D and d, inherit one from each parent, can also be 2 alleles D and D.

d is silent so 2 alleles d and d genotype would cause RhD negative phenotype.

Question 14

What can the anti-d antibody cause?

Answer 14

Can cause transfusion reactions and haemolytic disease of the foetus and new-born.

Avoid exposing RhD negative people to D antigen through transfusion. RhD negative blood should be given to RhD negative people.

Question 15

What is the aim of pre-transfusion testing?

Answer 15

Identify ABO and RhD group of patient

Identify presence of clinically significant red cell antibodies

This allows for selection of appropriate blood for transfusion

Question 16

What is antisera?

Answer 16

Using reagents with known antibody specificity to identify antigens present on red cell.

Question 17

What are reagent red cells?

Answer 17

Using reagents with known antigen specificity to identify antibodies present on red cell.

Question 18

What are the indirect and direct antiglobulin tests?

Answer 18

The direct and indirect Coombs tests, also known as antiglobulin test (AGT), are blood tests used in immunohematology.

The direct Coombs test detects antibodies that are stuck to the surface of the red blood cells.

The indirect Coombs test detects antibodies that are floating freely in the blood.

Question 19

Stages of indirect antiglobulin test?

Answer 19

Reagent red cells expressing known antigen(s)

Add patient plasma

Add anti-human globulin

Look for agglutination

(Agglutination indicates the presence of an antibody)

Question 20

What are the points to consider for selecting blood for transfusion?

Answer 20

Matched for, or compatible with patient’s ABO and RhD group

Consider presence of red cell antibodies

Perform crossmatch to check donor cells are compatible with patient plasma, uses indirect anti-globulin (agglutination indicates donor cells are incompatible with patient plasma).

Agglutination = firmly stick or be stuck together to form a mass

Question 21

Indications for red cell transfusion?

Answer 21

Symptomatic anaemia Hb<70g/L (80g/L if cardiac disease)

Major bleeding

Always consider cause before transfusion
* Is there an alternative?

Transfuse a single unit of red cells and then reassess patient 9in stable, non-bleeding patients).

Question 22

Indications for platelet transfusion?

Answer 22

Prophylaxis in patients with bone marrow failure and very low platelet counts

Treatment of bleeding in thrombocytopenic patient

Prophylaxis prior to surgery/ procedure in thrombocytopenic patient

Always consider the cause before transfusion

Question 23

Indication for FFP transfusion?

Answer 23

Treatment of bleeding in patient with coagulopathy (PT ratio >1.5)

Prophylaxis prior to surgery or procedure in patient with coagulopathy (PT ratio >1.5)

Management of massive haemorrhage

Transfuse early in trauma

Not in absence of bleeding/ planned procedure

Question 24

When is monitoring required during transfusion?

Answer 24

Observation before blood is commenced

Observation at 15 minutes

Observations within 60 mins of completion