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M103 T2 > M103 T2 L8 transfusion > Flashcards

M103 T2 L8 transfusion Flashcards

1
Q

How do antibodies for ABO antigens occur?

A

naturally

due to cross reactivity with gut bacterial antigens

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2
Q

What are the functions of IgM antibodies?

A

able to fix complement and HEMOLYSIS

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3
Q

What are the four blood groups?

A

A - most common
O - second most common
B - rare
AB - very rare

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4
Q

What are the antigen and atby types for blood group A?

A

A antigens on rbc surfaces, B atbys in blood plasma

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5
Q

What are the antigen and atby types for blood group B?

A

B antigens on rbc surfaces, A atbys in blood plasma

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6
Q

What are the antigen and atby types for blood group AB?

A

both A and B antigens on rbc surfaces, no A or B atbys in blood plasm

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7
Q

What are the antigen and atby types for blood group O?

A

neither A or B antigens on rbc surfaces, both A and B antibodies in blood plasma

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8
Q

What are the antigen and atby types for blood group O?

A

neither A or B antigens on rbc surfaces, both A and B antibodies in blood plasma

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9
Q

What are the genotypes for the different blood groups?

A

OO
AA or AO
BB or BO
AB

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10
Q

How can gel cards be used for blood grouping?

A

blood from the sample is put in a tube and centrifuged
if the blood is at the top of the column, then there has been an agglutination reaction
if the blood is at the bottom, then there has been no reaction
the control should be negative

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11
Q

What is the function of gel cards?

A

for determining the blood type of a blood sample

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12
Q

Which blood group is protective for COVID19 and which is a risk factor?

A

protective - blood group O

rf - blood group A

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13
Q

How does the reverse grouping assay work?

A

by mixing the patients’ blood plasma with RBCs of a known type

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14
Q

What does the lab do when a sample is sent in?

A

they test the ABO group of the rbcs

they screen the plasma for atypical atbys

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15
Q

How do atypical antibodies arise?

A

sensitisation via foreign RBC antigens from blood transfusions or pregnancy

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16
Q

What can cause blood transfusion reactions?

A

Atypical antibodies if the patient is transfused with incompatible blood in the future

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17
Q

How does the Coombs test work?

A

uses anti-immunoglobulin antibody to agglutinate red cells

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18
Q

What are the two types of Coombs (anti-globulin) tests?

A

direct anti-globulin test (DAT)

indirect anti-globulin test (IAT)

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19
Q

What is the direct anti-globulin tests used for?

A

tells us if the rbcs are coated with antibody

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20
Q

In what circumstances does the direct anti-globulin test come back positive?

A

after a transfusion reaction and in HDN

in autoimmune haemolytic anaemia

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21
Q

What is a feature of people that are Rh positive?

A

can’t develop antibodies

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22
Q

What percentage of people are Rh negative?

A

15%

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23
Q

What are the exceptions for Rhesus sensitisation?

A

transfusion of Rh pos blood

pregnant with a Rh pos baby

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24
Q

What type of antibodies are developed by Rh negative people with rhesus sensitisation?

A

IgG-type antibodies

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25
Q

What is the most important antigen?

A

RhD

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26
Q

What are the potential effects of haemolytic disease of the newborn for the baby? (JAKern)

A

jaundice
anaemia
kernicterus

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27
Q

How does the direct anti-globulin test (DAT) work?

A

detects atbys stuck to the surface of the rbcs

since these atbys sometimes destroy rbcs, this test can help clarify anemia

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28
Q

How does the indirect anti-globulin test (IAT) work?

A

patient serum / plasma is incubated with rbcs
antihuman globulin is added
if an atbyis present in the serum, will cause agglutination between the rbcs and their corresponding antigens

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29
Q

What is the indirect anti-globulin test used for?

A

in the lab for testing blood group antigen
it detects antibodies floating freely in the blood
can tell us if a patient is positive for Rhesus and other blood groups b

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30
Q

What is a consequence of Rhesus D sensitisation?

A

Persons who develop Rh antibodies cannot be given Rh pos blood

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31
Q

What steps are taken to prevent haemolytic disease of the newborn?

A

Pregnant women have the ABO + Rh blood group check at 12 weeks
Rh-ve women (15%) receive anti-D antibody i.m. injection at 28 and 34 weeks to prevent sensitisation
Baby tested at birth and if Rh+ve, mother receives further anti-D until Kleihauer test (foetal cells) becomes negative

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32
Q

What steps are taken if a pregnant woman has already developed Rhesus sensitisation?

A

the foetus requires monitoring via trans-cranial Doppler scan
may require intra-uterine transfusions if signs of anaemia

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33
Q

What are the main componenets in a bag of donated blood?

A 
Red cells
Buffy coat
Plasma
Water
Electrolytes
Additives
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34
Q

What can low albumin levels indicate?

A

a problem with the liver or kidneys

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35
Q

What is the function of albumin?

A

to keep fluid in the bloodstream so that it doesn’t leak into other tissues

36
Q

What is the purpose of apheresis?

A

to remove one particular component from blood

37
Q

How does apheresis work?

A

remove whole blood from a donor or patient
separate the blood into individual components
re-introduced the remaining blood components back into the bloodstream of the patient / donor

38
Q

What temperature are platelets stored at and for how long do they last?

A

stored at 22oC for 5 days

39
Q

What temperature are rbcs stored at and for how long do they last?

A

stored at 4 oC for 35 days

40
Q

What temperature is plasma stored at and for how long do they last?

A

stored at -30 oC for 12 months

41
Q

What does a junior doctor need to know about blood transfusion?

A 
When to give a blood transfusion
What type of transfusion to give
How to request blood transfusion
How to monitor a blood transfusion
What are the problems and complications
42
Q

What circumstances should be met to give a blood transfusion?

A

Severe acute blood loss
Elective surgery associated with significant blood loss
Medical transfusions
Anaemia

43
Q

Which three things constitute to Severe acute blood loss?

A

Severe trauma e.g., road traffic accident
Massive GI blood loss
Obstetric blood loss

44
Q

What are examples of medical transfusions that might require a blood transfusion?

A

Cancer
chemotherapy
renal failure

45
Q

What circumstances should be met to give a blood transfusion for anaemia?

A

only for symptomatic anaemia or if refractory to haematinic replacement
bone marrow failure
haemoglobinopathy

46
Q

What are the components of donated blood?

A

Red cells
Platelets
Fresh frozen plasma
Cryoprecipitate (fibrinogen)

47
Q

What are the plasma derivatives of donated blood?

A

Immunoglobulin
Coagulation factors
Albumin

48
Q

What things must be in place before you can go ahead with transfusion testing?

A

Informed consent
Record reason for transfusion in notes
Sampler – ask patient their name and check ID on wristband
Make sure the patient gets the “Right blood at the Right time”
Most errors are caused by failure to follow procedures

49
Q

What information must you obtain before you can go ahead with transfusion testing?

A 
ID (surname, name, DOB, hospital number)
Blood group
Previous transfusions
Reason for request
Type of blood product and amount
Special requests
When and where
Doctor (audit trail)
50
Q

What information must be put on the blood sample label after performing a blood transfusion test?

A

ID
Signature of phlebotomist (audit trail)
Date

51
Q

What information must NOT be put on the blood sample label after performing a blood transfusion test?

A

do not use addressograph labels

do not pre-label a sample

52
Q

When testing for compatability between a sample blood test and a donor’s sample, what must be established?

A

the ABO and Rh groups
if there are atypical antibodies in patient serum
that the appropriate donor blood is chosen
that compatibility testing between donor cells and patient serum determines suitability
that the blood issued has the appropriate label

53
Q

How long does it take to obtain O negative blood and when is it used?

A

5 mins
used in emergencies - referred to as emergency blood
is universal with all patients

54
Q

How long does it take to obtain Group Compatible blood?

A

10 - 15 minutes

55
Q

How long does it take to obtain “Fully screened and cross-matched” blood?

A

approximately 45 minutes

may be hours if antibodies are found

56
Q

What are the potential reactions to blood transfusions?

A 
Major ABO incompatibilities
Febrile non-haemolytic reactions
Fluid overload
Anaphylaxis and severe allergic reactions
Minor allergic reactions
Delayed transfusion reactions
TRALI
57
Q

Which three things can major ABO incompatibilities lead to?

A

Acute renal failure
Disseminated intravascular coagulation
Death

58
Q

What types of infections can be transmitted through blood transfusions?

A

Bacterial infections
Viral infections
Malaria
vCJD

59
Q

What are three examples of bacterial infections that can be transmitted through blood transfusions?

A

syphilis
pyogenic infections
contamination infections (pseudomonas)

60
Q

What are examples of viral infections that can be transmitted through blood transfusions?

A 
hepatitis B, C
HIV
HTLV
CMV
West Nile virus
61
Q

What are the potential physiological hazards to blood transfusions?

A

fluid overload

haemosiderosis

62
Q

How can fluid overload be avoided?

A

do not infuse too quickly

transfuse 1 unit over 4 hrs if elderly or evidence of heart failure

63
Q

What can fluid overload cause?

A

acute pulmonary oedema

64
Q

How can fluid overload be treated?

A 
with diuretics (frusemide) to remove fluid
can transfuse 1 unit over 2 hours in younger patients
65
Q

How does haemosiderosis occur?

A

iron is deposited in tissues

66
Q

How is iron deposited in haemosiderosis?

A

liver
heart
pancreas
skin

67
Q

How is haemosiderosis treated?

A

can treat by iron chelation

68
Q

What is unique about IgM?

A

it is the largest ATBY

it’s the first ATBY to appear in the response to initial exposure to an antigen.

69
Q

What is the shape of IgM?

A

pentameric

70
Q

What is the Coombs test otherwise known as?

A

the anti-globulin test

71
Q

What is the function of the Coombs test?

A

to detect ATBYs / complement proteins attached to the surface of rbcs

72
Q

Which is more common Rh negative or positive?

A

positive

73
Q

What does being Rh negative?

A

is not an illness and usually does not affect health

However, it can affect pregnancy

74
Q

What do Rh antigens seem to be used for?

A

the transport of CO2 and/or ammonia across the plasma membrane

75
Q

Where are Rh antigens located?

A

on the surface of RBCs

76
Q

What is the gene that encodes Rh antigens?

A

the RHD gene

77
Q

What is another term for Rhesus haemolytic disease?

A

Hemolytic disease of the newborn

78
Q

When does Rhesus D sensitisation occur?

A

when a woman with RhD negative blood is exposed to RhD positive blood and develops an immune response to it

79
Q

Which virus is associated with AIDS?

A

HTLV

80
Q

What are the effects of vCJD?

A

psychiatric problems, behavioral changes and painful sensations

81
Q

What is the function of forward grouping assays?

A

to test for which antigens are expressed on RBCs

82
Q

What are the four main types of globulins?

A

alpha 1, alpha 2, beta, and gamma

83
Q

What is the role of gobulins?

A

maintaining liver function, blood clotting, and fighting infection

84
Q

What are the most significant gamma globulins?

A

antibodies

85
Q

What is another term for ATBY’s?

A

immunoglobins

86
Q

What substances are contained in the Buffy coat?

A

WBCs and Rh antigens

87
Q

What is the most common reason for blood transfusion fatalities?

A

TRALI

M103 T2 (9 decks)

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