Transfusions

Question 1

What is the minimum criteria that blood donors must meet?

Answer 1

Hb 135g/l in men and 125g/l in women

Weight at least 50kg

Question 2

How is the safety of blood donations ensured?

Answer 2

Donor selection questionnaire

Take contact details in case donor becomes unwell after donation

Question 3

Where are all the blood donations taken in Scotland processed?

Answer 3

SNBTS headquarters in Edinburgh

Question 4

How is blood processed when it is taken to the blood labs?

Answer 4

Bag of whole blood centrifuged to separate into component parts
Undergo microbiological testing = HIV, Hep B/C/E, HTLV, syphilis

Question 5

What components is blood separated into?

Answer 5

Red cell = stored at 4 degrees for 35 days
FFP = stored at -30 degrees for 3 years
Platelets = stored at 22 degrees for 7 days with agitation (shaken gently)

Question 6

What blood products are available from the transfusion lab?

Answer 6

Blood components = red cells, FFP, platelets, cryoprecipitate
Blood products = anti-D Ig, prothrombin complex concentrate
Pharmacy products = IV Ig, human albumin, specific Ig

Question 7

What determines blood groups?

Answer 7

Red cell antigens = contained within cell membrane

Question 8

What are the two most important blood group systems?

Answer 8

ABO system = encoded by ABO gene

Rh system = encoded by RhD and RhCE genes

Question 9

Where is the ABO gene located?

Answer 9

On chromosome 9

Question 10

What is the inheritance of the ABO gene?

Answer 10

Receive one from each parent

Question 11

What do A and B genes code for?

Answer 11

Transferases = modify precursor called H substance on the red cell membrane

Question 12

What does inheritance of a B gene cause?

Answer 12

Expression of a B antigen

Question 13

What is the expression of different ABO groups?

Answer 13

A and B are dominant over O but are co-dominant with each other
O is silent = no O antigen (merely lack of A or B)

Question 14

What is the phenotype of a blood group?

Answer 14

Which antigens are expressed (e.g group A)

Question 15

What is the genotype of a blood group?

Answer 15

Which genes are present (e.g AA or AO)

Question 16

What genotypes are the different ABO phenotypes?

Answer 16

Group O = OO
Group A = AA or AO
Group B = BB or BO
Group AB = AB

Question 17

What is Landsteiner’s law?

Answer 17

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

Question 18

What does Landsteiner’s law cause in practice?

Answer 18

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

Question 19

What are the antibodies associated with different ABO blood groups?

Answer 19

Group A = anti-B antibody
Group B = anti-A antibody
Group AB = neither
Group O = anti-A and anti-B antibodies

Question 20

If a blood donor is group O, which recipient blood groups will it be compatible with?

Answer 20

Groups O, A, B and AB

Question 21

What is the only blood group that a donor sample that is blood group AB will be compatible with?

Answer 21

Group AB

Question 22

What are blood groups will a donor sample that is group A be compatible with?

Answer 22

Groups A and AB (group B is compatible with B and AB)

Question 23

How common is RhD+ status in the population?

Answer 23

Occurs in 85% of the population

Question 24

What are the alleles of the Rhesus system?

Answer 24

2 alleles = D and d
One inherited from each parent
d is silent

Question 25

What are the genotypes associated with the different Rh system phenotypes?

Answer 25

``` Rh+ = DD or Dd Rh- = dd ```

Question 26

Why is the Rh system important?

Answer 26

RhD antigen is very immunogenic

Question 27

What is the clinical relevance of anti-D antibody?

Answer 27

Can cause transfusion reactions and haemolytic disease of the newborn

Question 28

What kind of blood should RhD- patients receive?

Answer 28

RhD- blood = must avoid exposing them to D antigens

Question 29

What are the aims of pre-transfusion testing?

Answer 29

Identify ABO and RhD group of patient | Identify presence of clinically significant red cell antibodies

Question 30

How is ABO grouping carried out?

Answer 30

Using forward and reverse testing

Question 31

What occurs in forward ABO grouping?

Answer 31

Reagents called antisera with known specific antibody used to identify antigens present on red cells

Question 32

What occurs in reverse ABO grouping?

Answer 32

Reagent red cells with known antigen specificity used to identify antibodies present in plasma

Question 33

How are the antigens present on red cells identified?

Answer 33

Test patient's red cells using anti-A, B and D antisera = IgM reagents cause direct agglutination

Question 34

How are the antigens present in plasma identified?

Answer 34

Test patient's plasma against reagent red cells of groups A and B

Question 35

How is a patient's blood group defined?

Answer 35

By identifying the red cell and plasma antigens present

Question 36

How are antibodies screened for in blood?

Answer 36

Test patient's plasma against several reagent red cells which express a known range of antigens

Question 37

What test is used to screen for antibodies in blood?

Answer 37

Indirect anti-globulin test = anti-human globulin added to plasma to facilitate red cell agglutination

Question 38

What does agglutination in the indirect anti-globulin test indicate?

Answer 38

Presence of an antibody

Question 39

How is blood selected for transfusion?

Answer 39

Blood is match, or compatible, with patient's ABO and RhD group and donor cells are compatible with patient plasma

Question 40

How is the compatibility of donor cells with patient plasma checked?

Answer 40

By performing a cross match

Question 41

What occurs in an IAT crossmatch?

Answer 41

Patient plasma and anti-human globulin are added to donor cells = agglutination means donor cells are incompatible

Question 42

What are the indications for red cell transfusion?

Answer 42

Symptomatic anaemia = Hb <70g/l or <80g/l if cardiac disease Major bleeding

Question 43

How are patients assessed during a red cell transfusion?

Answer 43

Transfuse single unit of red cells then reassess patient

Question 44

What are the indications for platelet transfusion?

Answer 44

Prophylaxis in bone marrow failure + very low platelets Treatment of bleeding in thrombocytopenic patient Surgery prophylaxis in thrombocytopenic patient

Question 45

What are the indications for FFP transfusion?

Answer 45

Treatment of bleeding in coagulopathy ( PT ratio >1.5) Surgery prophylaxis in coagulopathy (PT ratio >1.5) Management of massive haemorrhage

Question 46

How should FFP transfusions be used?

Answer 46

Transfuse early in trauma | Never use in absence of bleeding or planned procedure

Question 47

How must blood sample labels be filled in?

Answer 47

Fill in at bedside and must be done correctly with no corrections

Question 48

When are observations taken during a transfusion?

Answer 48

Before blood is commenced, at 15 minutes into transfusion and within 60 minutes of completion

Question 49

What is the full transfusion procedure?

Answer 49

Request - sample - sample receipt - testing - component selection - labelling - collection - prescription - administration

Question 50

What steps of the transfusion procedure take place in the lab?

Answer 50

Sample receipt - testing - component selection - labelling