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Haematology > Blood Groups and Transfusion > Flashcards

Blood Groups and Transfusion Flashcards

1
Q

ABO in blood are

A

red cell antigens

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2
Q

what chromosome determines the red cell antigens?

A

chromosome 9

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3
Q

what do the gene codes for A and B allow for?

A

code for transferases which modify

precursor called ‘H substance’ on red cell membrane

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4
Q

how are ABO genes inherited?

A

1 from each parent

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5
Q

what is the inheritance pattern of A, B and O genes?

A

A and B are dominant over O
A and B are co-dominant
O is silent

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6
Q

what is landsteiners law?

A

When an individual lacks the A or B antigen the
corresponding antibody is produced in their plasma
Naturally occurring antibodies cause haemolysis of red cells expressing the specific antigen = via gut bacteria similar in structure to A and B antigen,

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7
Q

people with blood group O have genotype…

A

OO

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8
Q

people with blood group A have genotype…

A

AA or AO

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9
Q

people with blood group B have genotype…

A

BB or BO

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10
Q

people with blood group AB have genotype…

A

AB

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11
Q

people with blood group A have which antigen on red cells?

A

A

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12
Q

people with blood group B have which antigen on red cells?

A

B

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13
Q

people with blood group AB have which antigen on red cells?

A

A and B

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14
Q

people with blood group O have which antigen on red cells?

A

Neither

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15
Q

people with blood group A have which antibody in the plasma?

A

anti-B

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16
Q

people with blood group B have which antibody in the plasma?

A

anti-A

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17
Q

people with blood group AB have which antibody in the plasma?

A

neither

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18
Q

people with blood group O have which antibody in the plasma?

A

anti-A and anti-B

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19
Q

people with blood group O can receive blood from which groups?

A

O only

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20
Q

people with blood group A can receive blood from which groups?

A

A and O

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21
Q

people with blood group B can receive blood from which groups?

A

B and O

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22
Q

people with blood group AB can receive blood from which groups?

A

A, B, O, AB

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23
Q

what are the two main blood group systems?

A

ABO, Rh system

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24
Q

what is the genotype of RhD+?

A

DD or Dd

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25
Q

what is the genotype of RhD-?

A

dd

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26
Q

what is the inheritance pattern of RhD?

A
  • 2 alleles D and d, inherit one from each parent
  • d is silent
  • need dd to be negative
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27
Q

when does RhD system cause problems?

A

transfusion reactions and haemolytic disease of the fetus and newborn

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28
Q

how does RhD cause problems?

A

exposing RhD negative people to D antigen (RhD+)

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29
Q

what is the minimum criteria for blood donation?

A

– Hb 135g/L men
– Hb 125g/L women
– Weight 50kg

30
Q

what microbiological testing do blood donations go through?

A

HIV, Hep B, Hep C, Hep E, HTLV, Syphilis

31
Q

how long are red cells stored for?

A

4°C for 35 days

32
Q

how long is FFP stored for?

A

-30°C for 3 years

33
Q

how long are platelets stored for?

A

22°C for 7 days with agitation

34
Q

what blood components are available via donation?

A

– Red cells, FFP, platelets, cryoprecipitate

35
Q

what blood products are available via donation?

A

– Anti-D immunoglobulin, prothrombin complex concentrate

36
Q

what blood products are available via pharmacy?

A

– Iv immunoglobulin, human albumin, specific Ig

37
Q

what is vital in pre-transfusion testing?

A
  1. Identify ABO and RhD group of patient

2. Identify presence of clinically significant red cell antibodies

38
Q

what two tests are used for ABO grouping?

A

Direct Coombs

Indirect Coombs

39
Q

what is direct coombs test?

A

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

40
Q

what is indirect coombs test?

A

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

41
Q

what is the summary of the reaction of a direct coombs test?

A

antigen on red cells + antibody specific for antigen of interest = agglutination of red cells

42
Q

what is the summary of the reaction in a indirect coombs test?

A

Red Cells + Antibody + Sensitisation + AHG = agglutination (indicates presence of antibody)

43
Q

what is the process of a direct coombs test?

A

– Test patient’s red cells with anti-A, anti-B and anti-D antisera
– identify antigens on the red cells
– IgM reagents- direct agglutination

44
Q

what is the process of a indirect coombs test?

A

– Reagent red cells (group B to confirm anti B)

– Addition of anti-human globulin (AHG) to plasma/ red cell suspension facilitates red cell agglutination

45
Q

why is AHG added to plasma/red cell suspension?

A

– IgG only have 2 binding sites (won’t have agglutination) – add anti-globulin – if antibody has bound to red cell, anti-globulin binds and induces agglutination

46
Q

what are the indications for red cell transfusion?

A

Symptomatic anaemia Hb<70g/L (80g/L if cardiac disease)
Major bleeding
Always consider cause before transfusion - alternative?
Transfuse a single unit of red cells and then reassess patient

47
Q

what are the indications for platelet what are the indications for platelet transfusion??

A
  • 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
48
Q

what are the indications for FFP transfusion?

A
  • 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
49
Q

what are the 9 steps in blood transfusion?

A
  1. Request
  2. Sample
  3. Sample Receipt
  4. Testing
  5. Component Selection
  6. Labelling
  7. Collection
  8. Prescription
  9. Administration
50
Q

when is the patient observed during blood transfusion?

A
  • Observations before blood is commenced
  • Observations at 15 minutes
  • Observations within 60 minutes of completion
51
Q

what are the different types of transfusion reactions?

A

Acute Transfusion Reactions (ATR)
Acute Haemolytic Transfusion Reaction (AHTR)
Transfusion Associated Circulatory Overload
Mild Reaction
Delayed Haemolytic Transfusion Reactions
TRALI (transfusion associated lung injury)

52
Q

when do acute transfusion reactions occur?

53
Q

what are the symptoms of ATR?

A

chills, rigors, rash, flushing, feeling of impending doom, collapse, loin pain, resp distress

54
Q

what are the signs of ATR?

A

fever, tachycardia, hypotension, tachycardia

55
Q

what is initial management in all transfusion reactions?

A
  1. Stop the transfusion
  2. Assess the patient urgently ABCDE approach
    – BP, pulse, temp, oxygen sats, clinical examination
  3. Re-check compatibility tag against patient details and inspect pack for evidence of contamination
  4. Document event in medical notes
56
Q

what evidence could point to a severe or life threatening reaction?

A
  • Evidence of life threatening airway/ breathing or circulatory problem
  • Evidence of wrong component transfused/ bacterial contamination
57
Q

what is the management of bacterial contamination of blood component

A
  • Culture patient and remains of unit
  • Treat supportively and with broad spectrum antimicrobials
  • Need to inform transfusion lab so other units can be quarantined
58
Q

what the mechanism of AHTR?

A

ABO incompatibility

59
Q

what is the pathophysiology of AHTR?

A

Binding of IgM anti-A or –B antibodies to their corresponding antigen leads to complement activation and lysis of transfused cells
Release of inflammatory cytokines
intravascular coagulation, renal failure

60
Q

what are the consequences of AHTR?

A

Shock, increased vascular permeability, disseminated intravascular coagulation, renal failure, Often fatal

61
Q

what is the transfusion lab management of AHTR?

A

o Repeat ABO and RhD group of pre and post transfusion samples - Is there a discrepancy?
o Direct antiglobulin test - Is there antibody bound to donor cells?
o Repeat crossmatch - Are the donor unit(s) incompatible?
o Send remains of unit for culture

62
Q

what are the clinical features of Transfusion Associated Circulatory Overload?

A

– Respiratory distress within 6 hours of transfusion
– Raised blood pressure
– Raised JVP
– Positive fluid balance

63
Q

what are the risk factors for Transfusion Associated Circulatory Overload?

A

– Elderly patients, cardiac failure, low albumin, renal impairment, fluid overload

64
Q

what is the management of Transfusion Associated Circulatory Overload?

A

– Oxygen and supportive care as required
– Diuretics - furosemide
– Consider slowing rate of further transfusions
– Consider diuretics with future transfusion
– Only transfuse minimum volume required
– Aim to identify patients at risk before first transfusion

65
Q

what are the causes of mild transfusion reactions?

A

– Febrile non-haemolytic transfusion reaction

– Mild allergic reaction

66
Q

what are the clinical features of mild transfusion reactions?

A

•Isolated temp rise >38 and rise of 1-2 degrees or rash only

67
Q

what is the management of mild transfusion reactions?

A

– Continue transfusion- consider slowing rate
– Close monitoring of patient in case condition worsens
– Consider paracetamol/ anti-histamine

68
Q

when does Delayed Haemolytic Transfusion Reactions occur?

A

Extravascular haemolysis 5-10 days post transfusion

69
Q

what is the pathophysiology of Delayed Haemolytic Transfusion Reactions?

A

Patient mounts delayed immune response to red cell antigen- usually IgG
o Positive DAT

70
Q

what are the features of Delayed Haemolytic Transfusion Reactions seen in blood tests?

A

o Hb may drop, raised bili, LDH

o Positive DAT and detection of alloantibody

71
Q

what is the Resuscitation of Severe Allergic Transfusion Reaction?

A 
Lie patient
Administer adrenaline
Administer chlorpheniramine
Administer salbutamol
Administer corticosteroids

Haematology (13 decks)

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