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M103 T2 L8 transfusion Flashcards

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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
What is the most important antigen?
RhD
26
What are the potential effects of haemolytic disease of the newborn for the baby? (JAKern)
jaundice anaemia kernicterus
27
How does the direct anti-globulin test (DAT) work?
detects atbys stuck to the surface of the rbcs | since these atbys sometimes destroy rbcs, this test can help clarify anemia
28
How does the indirect anti-globulin test (IAT) work?
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
29
What is the indirect anti-globulin test used for?
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
30
What is a consequence of Rhesus D sensitisation?
Persons who develop Rh antibodies cannot be given Rh pos blood
31
What steps are taken to prevent haemolytic disease of the newborn?
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
32
What steps are taken if a pregnant woman has already developed Rhesus sensitisation?
the foetus requires monitoring via trans-cranial Doppler scan may require intra-uterine transfusions if signs of anaemia
33
What are the main componenets in a bag of donated blood?
``` Red cells Buffy coat Plasma Water Electrolytes Additives ```
34
What can low albumin levels indicate?
a problem with the liver or kidneys
35
What is the function of albumin?
to keep fluid in the bloodstream so that it doesn't leak into other tissues
36
What is the purpose of apheresis?
to remove one particular component from blood
37
How does apheresis work?
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
What temperature are platelets stored at and for how long do they last?
stored at 22oC for 5 days
39
What temperature are rbcs stored at and for how long do they last?
stored at 4 oC for 35 days
40
What temperature is plasma stored at and for how long do they last?
stored at -30 oC for 12 months
41
What does a junior doctor need to know about blood transfusion?
``` 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
What circumstances should be met to give a blood transfusion?
Severe acute blood loss Elective surgery associated with significant blood loss Medical transfusions Anaemia
43
Which three things constitute to Severe acute blood loss?
Severe trauma e.g., road traffic accident Massive GI blood loss Obstetric blood loss
44
What are examples of medical transfusions that might require a blood transfusion?
Cancer chemotherapy renal failure
45
What circumstances should be met to give a blood transfusion for anaemia?
only for symptomatic anaemia or if refractory to haematinic replacement bone marrow failure haemoglobinopathy
46
What are the components of donated blood?
Red cells Platelets Fresh frozen plasma Cryoprecipitate (fibrinogen)
47
What are the plasma derivatives of donated blood?
Immunoglobulin Coagulation factors Albumin
48
What things must be in place before you can go ahead with transfusion testing?
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
What information must you obtain before you can go ahead with transfusion testing?
``` 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
What information must be put on the blood sample label after performing a blood transfusion test?
ID Signature of phlebotomist (audit trail) Date
51
What information must NOT be put on the blood sample label after performing a blood transfusion test?
do not use addressograph labels | do not pre-label a sample
52
When testing for compatability between a sample blood test and a donor's sample, what must be established?
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
How long does it take to obtain O negative blood and when is it used?
5 mins used in emergencies - referred to as emergency blood is universal with all patients
54
How long does it take to obtain Group Compatible blood?
10 - 15 minutes
55
How long does it take to obtain “Fully screened and cross-matched” blood?
approximately 45 minutes | may be hours if antibodies are found
56
What are the potential reactions to blood transfusions?
``` Major ABO incompatibilities Febrile non-haemolytic reactions Fluid overload Anaphylaxis and severe allergic reactions Minor allergic reactions Delayed transfusion reactions TRALI ```
57
Which three things can major ABO incompatibilities lead to?
Acute renal failure Disseminated intravascular coagulation Death
58
What types of infections can be transmitted through blood transfusions?
Bacterial infections Viral infections Malaria vCJD
59
What are three examples of bacterial infections that can be transmitted through blood transfusions?
syphilis pyogenic infections contamination infections (pseudomonas)
60
What are examples of viral infections that can be transmitted through blood transfusions?
``` hepatitis B, C HIV HTLV CMV West Nile virus ```
61
What are the potential physiological hazards to blood transfusions?
fluid overload | haemosiderosis
62
How can fluid overload be avoided?
do not infuse too quickly | transfuse 1 unit over 4 hrs if elderly or evidence of heart failure
63
What can fluid overload cause?
acute pulmonary oedema
64
How can fluid overload be treated?
``` with diuretics (frusemide) to remove fluid can transfuse 1 unit over 2 hours in younger patients ```
65
How does haemosiderosis occur?
iron is deposited in tissues
66
How is iron deposited in haemosiderosis?
liver heart pancreas skin
67
How is haemosiderosis treated?
can treat by iron chelation
68
What is unique about IgM?
it is the largest ATBY | it's the first ATBY to appear in the response to initial exposure to an antigen.
69
What is the shape of IgM?
pentameric
70
What is the Coombs test otherwise known as?
the anti-globulin test
71
What is the function of the Coombs test?
to detect ATBYs / complement proteins attached to the surface of rbcs
72
Which is more common Rh negative or positive?
positive
73
What does being Rh negative?
is not an illness and usually does not affect health | However, it can affect pregnancy
74
What do Rh antigens seem to be used for?
the transport of CO2 and/or ammonia across the plasma membrane
75
Where are Rh antigens located?
on the surface of RBCs
76
What is the gene that encodes Rh antigens?
the RHD gene
77
What is another term for Rhesus haemolytic disease?
Hemolytic disease of the newborn
78
When does Rhesus D sensitisation occur?
when a woman with RhD negative blood is exposed to RhD positive blood and develops an immune response to it
79
Which virus is associated with AIDS?
HTLV
80
What are the effects of vCJD?
psychiatric problems, behavioral changes and painful sensations
81
What is the function of forward grouping assays?
to test for which antigens are expressed on RBCs
82
What are the four main types of globulins?
alpha 1, alpha 2, beta, and gamma
83
What is the role of gobulins?
maintaining liver function, blood clotting, and fighting infection
84
What are the most significant gamma globulins?
antibodies
85
What is another term for ATBY's?
immunoglobins
86
What substances are contained in the Buffy coat?
WBCs and Rh antigens
87
What is the most common reason for blood transfusion fatalities?
TRALI

M103 T2 (9 decks)

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