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Haematology > The Blood Transfusion Laboratory > Flashcards

The Blood Transfusion Laboratory Flashcards

1
Q
  1. ALL blood cells have antigens , what part of the cell are they found?
A

Cell surface

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2
Q
  1. What type of molecules are antibodies? What are they more broadly classed as?
A

Antibodies are PROTEIN molecules

-> Immunoglobins

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3
Q
  1. What are the two main immunoglobin classes?
A

IgG and IgM

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4
Q
  1. Why are antibodies produced?
A

o Produced by the immune system following exposure to a foreign antigen and found in the plasma

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5
Q
  1. How many known blood group systems are there?
A

26

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6
Q
  1. Out of the 26 blood group systems, which 2 are most clinically important
A

ABO

Rh/D

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7
Q
  1. How can a blood transfusion help protect against certain antigens?
A

•Antigens in transfused blood stimulate patients to produce an antibody (only if the patient lacks the antigen).

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8
Q
  1. Is the freq of antibody production in a patient who has received a blood transfusion high or low?
A

•The frequency of antibody production is very low but increases the more transfusions that are given

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9
Q
  1. How does pregnancy stimulate antibody production?
A

Foetal antigen entering maternal circulation during pregnancy or at birth.

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10
Q
  1. Can environmental factors affect antibody production?
A

YES

ie naturally acquiring anti-A and anti-B

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11
Q
  1. How is an antibody-antigen reaction in vivo?
A

destruction of the cell either:
-directly when the cell breaks up in the blood stream (intravascular)
or
-indirectly when liver and spleen remove antibody coated cells (extravascular).

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12
Q
  1. How is an antibody-antigen reaction in vitro?
A

reactions are normally seen as agglutination tests

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13
Q
  1. What is Agglutination?
A
  • Agglutination is the clumping together of red cells into visible agglutinates by antigen-antibody reactions
  • Agglutination results from antibody cross-linking with the antigens.
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14
Q
  1. What can an agglutination test identify?
A

o The presence of a red cell antigen i.e. blood grouping.

o The presence of an antibody in the plasma i.e. antibody screening/identification.

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15
Q
  1. What is the clinical significance of ABO grouping systems?
A
  • A and B antigens very common (55% UK) , Anti-A, anti-B or anti-A,B antibodies very common (97% UK).
  • High risk of A or B cells being transfused into someone with the antibody in a random situation
  • ABO antibodies (worst type of transfusion) can activate complement causing intravascular haemolysis.
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16
Q 
16. For the following phenotypes of blood grouping systems, what are there red cell ANTIGENS:
A
B
O
AB
A

A=A
B=B
O=none
AB=A and B

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17
Q 
17.For the following phenotypes of blood grouping systems, what are there FREQUENCY in the Uk:
A
B
O
AB
A 
A= 43%
B = 9%
O = 45%
AB = 3%
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18
Q 
18.For the following phenotypes of blood grouping systems, what are there GENOTYPES :
A
B
O
AB
A 
A= AA or AO
B= BB or BO
O= OO
AB = AB
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19
Q 
19 ..For the following phenotypes of blood grouping systems, what are there red cell ANTIBODIES :
A
B
O
AB
A

A =B
B = A
O= A and B
AB = none

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20
Q
  1. How would you identify which blood group a patient belongs to?
A

Patients red cells and plasma are both tested:
Test patient’s red cells with anti-A, anti-B and anti-D
o agglutination =particular antigen is on the red cells
o no agglutination = antigen is absent
Test patient’s plasma with A and B cells
o agglutination =particular antibody is in the plasma or serum
o no agglutination =antibody is absent

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21
Q
  1. For blood transfusions it is important to check that the blood groups are compatible:
    For the following DONOR red cells:
    O
    A
    B
    AB
    - Are they compatible with a recipient blood group O
A

O - yes
A- no
B- no
AB- no

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22
Q
  1. For blood transfusions it is important to check that the blood groups are compatible:
    For the following DONOR red cells:
    O
    A
    B
    AB
    - Are they compatible with a recipient blood group A
A

O - yes
A - yes
B - no
AB -no

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23
Q
  1. For blood transfusions it is important to check that the blood groups are compatible:
    For the following DONOR red cells:
    O
    A
    B
    AB
    - Are they compatible with a recipient blood group B
A

O - yes
A- no
B- yes
AB - no

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24
Q
  1. For blood transfusions it is important to check that the blood groups are compatible:
    For the following DONOR red cells:
    O
    A
    B
    AB
    - Are they compatible with a recipient blood group AB?
A

O- yes
A - yes
B- yes
AB -yes

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25
Q
  1. The Rh blood grouping system has 50+ antigens, which one is the most important?
A

D antigen
85% of Uk is D+
15% of Uk is D-

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26
Q
  1. Besides D antigen , whats the 4 other main antigens in the Rh group ?
A

C
c
E
e

27
Q
  1. Is Rh (D) testing more important than ABO?
A

Nope

but its most important after ABO

28
Q
  1. What is the clinical significance of Rh for transfusion?
A

o D antigen is very immunogenic and anti-D is easily stimulated - PREVENTION!
o All Rh antibodies are capable of causing severe transfusion reaction- ANTIBODY DETECTION

29
Q
  1. What is the clinical significance of Rh in pregnancy?
A

o Rh antibodies are usually IgG and can cause haemolytic disease of the newborn.
o Anti-D is still most common cause of severe HDN

30
Q
  1. What is HDN?
A

Haemolytic disease of the newborn (HDN) is a blood problem in newborn babies. It occurs when your baby’s red blood cells break down at a fast rate

31
Q
  1. How can HDN occur?
A
  • Father is Rh+ , mother is Rh- , she’s carrying her first Rh+ baby
  • If during delivery, the foetus’s Rh antigens enter mothers blood = mother will make anti-Rh antibodies
  • If women becomes pregnant again with Rh+ baby, her anti Rh antibodies will cross placenta and damage foetal red blood cells
32
Q
  1. What is the purpose of HDN lab testing?
A

• Blood group and antibody screen at antenatal booking to identify pregnancies at risk of HDN
o D negative women who may need anti-D prophylaxis

33
Q
  1. At how many weeks pregnant is a blood group and antibody screen?
A

28 Weeks

34
Q
  1. What the progress throughout pregnancy is atypical antibodies are present?
A

•Atypical antibodies are quantified periodically to assess their potential effect on the foetus

35
Q
  1. What is the RAADP injection?
A

Routine antenatal anti-D prophylaxis (RAADP)
- injection of anti D will bind and remove any fetal D + red cells in circulation so the mother doesn’t produce a response

36
Q
  1. What are the two ways to receive RAADP?
A

1) 1500 iu of anti-D is given routinely at 28 weeks and a smaller dose (usually 500 iu) after delivery if baby RhD+
2) In some hospitals 2 smaller (500 iu) doses are given at 28 and 34 weeks instead of the 1 larger dose

37
Q
  1. Why else would a pregnant women be giving RAADP other than the baby being Rh+ and the mum being Rh-???
A

• Anti-D is also given after any event that may cause a feto-maternal haemorrhage (bleed between mum and foetus) such as:
o Abdominal trauma, Intrauterine death, Spontaneous or therapeutic abortion.

38
Q
  1. Explain the process of an antibody screening?
A
  • Patients serum is mixed with 3 selected screening cells, incubated for 15 minutes at 37oc and then centrifuged for 5 minutes.
  • Any clinically significant antibodies reacting at body temp should be detected and then identified using panel of known phenotyped red cells.
  • Specific antigen negative blood can then be provided for these patients to avoid stimulating an immune response.
  • When an antibody is detected, we must identify the antibody and assess it’s clinical significance for transfusion and in pregnancy.
39
Q
  1. How would you identify an antibody?
A
  • Compare pattern of reactions with each reagent cell of ID panel with the pattern of antigens on the reagent cells
  • Matching pattern will identify the antibody
40
Q
  1. Can IgM antibodies span the gap between RBC’s?
A

yes

41
Q
  1. Can IgG antibodies span the gap between RBC’s ? If not, why?
A

They cant

-They’re too small to overcome the zeta potential(very + charge)

42
Q
  1. What can allow IgG’s to span the gap between RBC’s?
A

LISS (low ionic strength saline) is negatively charged, so neutralises positive ZETA potential.
Therefore IgG can now span the gap.

43
Q
  1. What is the indirect Anti-globulin test (IAT) used for?
A

•Used to detect IgG antibodies
LISS counteracts Zeta potential= Results in agglutination
Used for:
o Screening for antibodies and Identifying antibodies
o Cross-matching donor blood with recipient plasma when there are known antibodies or a previous history of antibodies

44
Q
  1. What is an immediate spin cross match?
A

-Antibody screen is negative
-Checking donor red cells against patient plasma
o ABO check.
o Incubate for 2 – 5 minutes (room temp), spin and read.

45
Q
  1. What is a Full Indirect Antiglobulin test (IAT) cross-match
A
  • Antibody screen positive or patient has known antibody history.
  • Select antigen negative donor red cells and incubate with patient serum for 15 minutes at 37oC
46
Q
  1. What does a Negative ISX look like ? What about Positive ISX?
A

Negative ISX - just regular plasma

Positive ISX - yellowish liquid with a red dot in it (agglutination)

47
Q
  1. Following questions are about donors:
    - How many donations are collected annually?
    - What makes you eligible to be a blood donor
    - What % of the eligible donors , donate?
A
  • 2 MILL donations per year
  • Eligible if 17-65 yrs old and over 50kg
  • Only 4-6% of eligible people donate
48
Q
  1. What is the Uk Blood establisment?
A

MHRA licensed manufacturer of blood and products

49
Q
  1. How are donors selected for?
A

Questionnaire on lifestyle, health, not previously transfused

50
Q
  1. What is the collection procedure for donor blood testing?
A
  • Arm Cleansing

- Diversion Pouch

51
Q
  1. What do we have to test donor blood for before it can be used on a recipient?
A

Viral:
HIV 1+2, Hepatitis B/Hepatitis C, Syphilis, HTLV

Platelets:
-Bacteria
• ABO, RhD, K, antibody screen (compatibility).

52
Q
  1. How many cases is there believed to be of infections with vCJD from blood transfusion?
A

4

53
Q
  1. What is the risks of getting:
    - Hep B
    - Hep C
    - HIV Infection
    - HTLV Infection
A

1 in 1.2 million for HepB

1 in 28 million for Hep C

1 in 7 million for HIV

1 in 23 million for HTLV infection

54
Q
  1. How is Donor red cells stored?

* not sure if this is what the lecturer meant*

A

Concentrated red cells (packed cells) in a suspension of SAGM

55
Q
  1. What can we use donor red cells for?
A
  • Red cells oxygen carrying capacity
  • Symptomatic anaemia
  • Exchange transfusion
  • If significant bleeding anticipated, activate the major haemorrhage protocol
56
Q
  1. What does FFP contain? What is to given to patients for?
A

Fresh Frozen Plasma:
• FFP contains all clotting factors
• Given for coagulopathy with associated bleeding

57
Q
  1. FFP requires clotting screens to monitor because it doesn’t have long after its thawed, roughly how long after it thaws can you use it and how long until it forms a major haemorrhage?
A

• Only has 24 hour life after thawing (five days for major haemorrhage)

58
Q
  1. How are donor platelets given and for what?
A
  • Adult pool of platelets from 4 donors (suspended in plasma from 1 donor)
  • Platelets required to create clots to reduce bleeding (coagulation factors).
59
Q
  1. Why is patient history important for a platelet transfusion?
A

• Some drugs given to reduce efficacy of platelets (anti-platelet agents e.g. aspirin) so patient history important.

60
Q
  1. Why would you give Cryoprecipitate , how much should you give , how do you monitor it?
A
  • Contains Factor VIII, VWF and fibrinogen
  • 2 units usually given at one time
  • Monitor fibrinogen levels by clotting screens
61
Q
  1. What are some regulations in place for blood transfusions/donors?
A
  • EU Blood Safety Directive
  • Blood Safety Quality Regulations
  • Better Blood Transfusion 3
  • MHRA inspections
  • CPA inspections
62
Q
  1. What is Haemovigilance
A

set of surveillance procedures covering the entire blood transfusion chain

63
Q
  1. Explain the procedural aspects of haemovigilance?
A

Serious Hazards of Transfusion (SHOT):
o Voluntary reporting
o Report all Serious adverse Events (SAE) and Serious adverse reactions (SAR)

Serious Adverse Blood reactions and events (SABRE):
o Mandatory reporting
o Report all SAR and SAE where the root cause error was the Quality system.

Haematology (8 decks)

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