Blood groups and transfusions Flashcards

1
Q

where are the blood groups located on the red cell

A

 Located on the surface of the red cell

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2
Q

what blood group system do sugar residues form

what blood group system to proteins for

A

 Sugar residues form one type of blood group system e.g. ABO - ABO polysaccharide antigens
 Proteins form another type of blood group system e.g. Rhesus (Rh)

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3
Q

what determines the blood group

A

 Genes determine what particular sugar or protein is produced and thus the blood group

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4
Q

what are antibodies

A
  • Antibodies are immunoglobulins in plasma which react specifically with their antigens e.g. the anti-A antibody reacts with the A antigen
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5
Q

what are autoantibodies

A
  • Can have autoantibodies – react with antigens present on the persons own red cells
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6
Q

what are alloantibodies

A

produced by person against antigens not present on persons own red cells

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7
Q

what are the two types of alloantibodies

A

naturally occurring (exposure to environment)

immune (contact with antigen)

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8
Q

what is agglutination

A

antibody binds to antigen and clumps stuff together

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9
Q

what antigens are in the ABO system

A
  • A and B polysaccharide antigens
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10
Q

what are the naturally occurring antibodies against the ABO system

A
  • Anti-a

- Anti-b

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11
Q

what are the immune antibodies agains the ABO system

A

IgM

IgG

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12
Q

what does IgM do

A
  • Cold-acting (bind at room temperature)

- Activate complement

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13
Q

what happens if there is an ABO mismatch transfusion

A

ABO antibodies can be IgG or IgM, if there is an ABO mismatch transfusion and this will activate haemolysis of red blood cells,

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14
Q

name the blood groups and what antibody they have in there plasma

A

 A (has anti-B in plasma)
 B (has anti-A in plasma)
 O (has anti-A and anti-B in plasma)
 AB (has no ABO antibody in plasma

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15
Q

what will the ABO blood groups be agglutinated by

A
  • Blood of group A will be agglutinated by anti-A
  • Blood group B will be agglutinated by anti B
  • Blood of group AB will be agglutinated by anti-A and anti-B
  • Blood group O will not be agglutinated by anti-a or anti-b
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16
Q

name the phenotypes of the blood groups and what there genotypes could be

A

A - AA or AO
B - BB or BO
AB - AB
O - OO

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17
Q

for each blood group name

  • blood group repent
  • antigen present
  • antibodies present
  • can receive blood groups
A

Blood group A

  • antigen present = A
  • antibodies present = B
  • can receive blood groups = A and O

Blood group B

  • antigen present = B
  • antibodies present = A
  • can receive blood groups = B and O

Blood group AB

  • antigen present = AB
  • antibodies present = None
  • can receive blood groups = A or B or O

Blood group O

  • antigen present = H
  • antibodies present = A and B
  • can receive blood groups = O
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18
Q

describe the rhesus blood group system

A

 3 pairs of proteins, inherited as triplet:
 D or no D (written as d)
 C or c
 E or e

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19
Q

what can antibodies against rhesus blood groups form

A

Can form only following exposure:
 Transfusion
 Pregnancy
 Transplantation

20
Q

describe Rh genotype and phenotype

A
  • Genes are in triplets
  • Depending on the phenotype you can try and predict the genotype
  • Inherit one triplet from each parent
  • Alleles are co-dominant
21
Q

how can phenotype and genotype of rhesus groups be determined

A
  • Phenotype can be determined serologically
  • CcDE red cells will agglutinate with anti-C, anti-c, anti-D, antiE, but not anti-e

genotype can be determined by molecular techniques

22
Q

if you are RhD positive what blood can you get

if you are RhD negative what blood can you get

A

RhD positive = RhD positive or RhD negatie

RhD negative = only RhD negative

23
Q

what happens if you are given the wrong RhD positive or RhD negative in a blood transfusion

A
  • can lead of haemolytic disease of the foetus and newborn
  • this is because the mother can form RhD antibodies which cause haemolysis
  • leads to fatal anaemia and neonatal jaundice which can cause brain damage
24
Q

how do you prevent haemolytic disease of the foetus

A

 Prophylaxis after a sensitising event during pregnancy Prophylactic anti-D Ig all D negative mothers in third trimester
 Postnatally if baby D positive
 Free fetal DNA testing for RHD typing of of fortus from maternal sample now available to help targeted Anti D prophylaxis

25
Q

what are the blood components and what can they be transfused as

A
  • Red cells for transfusion
  • Platelets – low platlet count
  • Plasma - uses fresh frozen plasma, cryoprecipitate plasam, fractionation – factor
26
Q

what are the three different types of plasma that can be used

A
  • fresh frozen plasma
  • cryoprecipitate
  • fractionation factor concentrates, immunoglobulin, albumin (non UK plasma)
27
Q

what are the conditions that red blood cells are stored at

A

 Stored at 4 deg C, Shelf life 35 Days,

28
Q

when should a red cell blood transfusion be sued

A

Blood loss
- Surgery, Trauma
 Obstetric haemorrhage

Bone marrow failure
 Leukaemia, cancer, drugs

Haemolysis
 Malaria, sepsis, immune, haemolytic disease of newborn

Inherited haemoglobin disorders
 Thalassaemia
 Sickle cell anaemia

29
Q

when should you avoid transfusion

A

Anaemia due to Iron, B12 or folate deficiency

- give haematinic replacement therapy instead.

30
Q

what are the complications of adverse effects of transfusion

A

non infectious
immune
• Acute Haemolytic transfusion reaction –ABO incompatible transfusion
• Delayed Haemolytic transfusion reaction
• Febrile non haemolytic
• Allergic - urticatial rash,
anaphylaxis
• Post transfusion purpura
• Transfusion related acute lung injury (TRALI)
• TA-GVHD

non immune
• Fluid overload (TACO)
• Iron overload (in multi-transfused)

infectious 
•	Viral (HBV, HCV, HIV, HepE  HTLV, CMV, EBV, parvovirus etc)
•	Bacterial
•	Syphilis
•	Parasites (malaria, trypanosomiasis)
•	Prions
31
Q

How do you take blood from a patient

A

 confirm identification by speaking to them (use wrist-band if unconscious)
 label tube after filling with blood with full name, date of birth and hospital record number
 ensure that no discrepancy between details on bottle and form
 sign both form and tube to confirm

32
Q

what are ABO incompatible transfusions all due to

A

all due to human error:
 Patient wrongly identified (unconscious)
 Patient wrongly identified (no wristband)
 Patient wrongly identified (human error)
 Patient wrongly identified (pre-transfusion sample from wrong patient)

33
Q

how does an indirect antiglobulin test work

A
  • Patietns serum with IgG
  • Incubation with reagent RBC
  • Binding to the IgG to reagent RBCs
  • Incubation with antibodies to human Ig
  • Agglutination (positive indirect coombs test)
34
Q

what do you do if the antibody screening is negative

A

 Electronic ‘crossmatch’
 If antibody screen negative can give ABO and Rh D compatible units without serological crossmatch – strict criteria apply
 95% of the blood issued is done this way

35
Q

how does serological cross matching work

A

 mix donor red cells and patient serum to check compatible
 Must do if antibody screen positive or not eligible for electronic ‘crossmatch’
 If red cell antibodies then select units negative for those antigens and serologically crossmatch to check compatibility

36
Q

how do you give a transfusion

A
  • Positively identify the patient by name and DOB and hospital number
  • Before transfusing must confirm
    o Identity of patient
    o Blood group of patient
    o Blood group of the unit of blood
    Start transfusion
    Monitor closely (especially initially)
    o Pulse, blood pressure and temperature
37
Q

what is the possible transfusion reaction

A
  • Restlessness,
  • Flushing
  • Anxiety
  • Abdominal pain
  • Nausea
  • Diarrhoea
  • Abdominal pain
  • Pain at venepuncture site
38
Q

what are the signs of a transfusion reaction

A
  • Fever
  • Hypotension
  • Haemoglobinguria
39
Q

what should you do if a transfusion reaction happens

A

Stop transfusion

- Maintain access with saline commence resuscitation

40
Q

How do you investigate a transfusion reaction

A

Take samples for
 full blood count, renal and liver function tests
 blood cultures,
 coagulation screen,

repeat compatibility testing
 pre and post transfusion plasma

 Direct Antiglobulin Test
 assessment of urine for haemoglobin
 High dependency management – renal support, DIC

41
Q

what is a delayed haemolytic transfusion reaction due to

A

Due to red cell Ab’s - IgG
 Rh system/ Kell/ Fya/ Jkb etc

  • might have already been exposed in the past therefore IgG is present, If the antibody goes below the point of detection the test might be negative
  • then if it is exposed again then you get an delayed haemolytic transfusion reaction
  • then the haemoglobin fails to rise and you get jaundice as a by product
42
Q

when does a delayed haemolytic transfusion reaction happen

A

 7 to 10 days post transfusion
 Failure of haemoglobin to rise
 Jaundice

43
Q

what test is used to test to see if a delayed haemolytic transfusion reaction has happened

A

 Direct Antiglobulin Test

44
Q

how common are delayed haemolytic transfusion reactions

A

 How common are red cell Abs?
 ~2-5% of transfused patients
 Much higher rates allo-immunisation in patients with Sickle Cell Disease ~ 20%
 give extended Rh(DCcEe) and K matched blood

45
Q

how does a direct antiglobulin test work

A
  • RBC with IgG or CS bound to membrane ( already coated with antibodies)
    incubation with antibodies to human ig and C3
  • Agglutination (positive-direct coombs test)
46
Q

where do you report transfusion adverse events

A

SHOT (Serious Hazards of Transfusion)
 Collects information on adverse events and feedbacks to hospitals to improve transfusion overall safety

 MHRA (Medicines and Healthcare products Regulatory Agency)
- SABRE (Serious Adverse Blood Reactions and Events