The Blood Transfusion Laboratory Flashcards
1
Q
- ALL blood cells have antigens , what part of the cell are they found?
A
Cell surface
2
Q
- What type of molecules are antibodies? What are they more broadly classed as?
A
Antibodies are PROTEIN molecules
-> Immunoglobins
3
Q
- What are the two main immunoglobin classes?
A
IgG and IgM
4
Q
- Why are antibodies produced?
A
o Produced by the immune system following exposure to a foreign antigen and found in the plasma
5
Q
- How many known blood group systems are there?
A
26
6
Q
- Out of the 26 blood group systems, which 2 are most clinically important
A
ABO
Rh/D
7
Q
- 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).
8
Q
- 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
9
Q
- How does pregnancy stimulate antibody production?
A
Foetal antigen entering maternal circulation during pregnancy or at birth.
10
Q
- Can environmental factors affect antibody production?
A
YES
ie naturally acquiring anti-A and anti-B
11
Q
- 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).
12
Q
- How is an antibody-antigen reaction in vitro?
A
reactions are normally seen as agglutination tests
13
Q
- 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.
14
Q
- 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.
15
Q
- 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.
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
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%
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
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
20
Q
- 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
21
Q
- 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
22
Q
- 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
23
Q
- 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
24
Q
- 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
25
25. The Rh blood grouping system has 50+ antigens, which one is the most important?
D antigen
85% of Uk is D+
15% of Uk is D-
26
26. Besides D antigen , whats the 4 other main antigens in the Rh group ?
C
c
E
e
27
27. Is Rh (D) testing more important than ABO?
Nope
| but its most important after ABO
28
28. What is the clinical significance of Rh for transfusion?
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
29. What is the clinical significance of Rh in pregnancy?
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
30. What is HDN?
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
31. How can HDN occur?
- 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
32. What is the purpose of HDN lab testing?
• 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
33. At how many weeks pregnant is a blood group and antibody screen?
28 Weeks
34
34. What the progress throughout pregnancy is atypical antibodies are present?
•Atypical antibodies are quantified periodically to assess their potential effect on the foetus
35
35. What is the RAADP injection?
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
36. What are the two ways to receive RAADP?
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
37. Why else would a pregnant women be giving RAADP other than the baby being Rh+ and the mum being Rh-???
• 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
38. Explain the process of an antibody screening?
* 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
39. How would you identify an antibody?
* 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
40. Can IgM antibodies span the gap between RBC's?
yes
41
41. Can IgG antibodies span the gap between RBC's ? If not, why?
They cant
| -They're too small to overcome the zeta potential(very + charge)
42
42. What can allow IgG's to span the gap between RBC's?
LISS (low ionic strength saline) is negatively charged, so neutralises positive ZETA potential.
Therefore IgG can now span the gap.
43
43. What is the indirect Anti-globulin test (IAT) used for?
•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
44. What is an immediate spin cross match?
-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
45. What is a Full Indirect Antiglobulin test (IAT) cross-match
* 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
46. What does a Negative ISX look like ? What about Positive ISX?
Negative ISX - just regular plasma
Positive ISX - yellowish liquid with a red dot in it (agglutination)
47
47. 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?
- 2 MILL donations per year
- Eligible if 17-65 yrs old and over 50kg
- Only 4-6% of eligible people donate
48
48. What is the Uk Blood establisment?
MHRA licensed manufacturer of blood and products
49
49. How are donors selected for?
Questionnaire on lifestyle, health, not previously transfused
50
50. What is the collection procedure for donor blood testing?
- Arm Cleansing
| - Diversion Pouch
51
51. What do we have to test donor blood for before it can be used on a recipient?
Viral:
HIV 1+2, Hepatitis B/Hepatitis C, Syphilis, HTLV
Platelets:
-Bacteria
• ABO, RhD, K, antibody screen (compatibility).
52
52. How many cases is there believed to be of infections with vCJD from blood transfusion?
4
53
53. What is the risks of getting:
- Hep B
- Hep C
- HIV Infection
- HTLV Infection
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
54. How is Donor red cells stored?
| * not sure if this is what the lecturer meant*
Concentrated red cells (packed cells) in a suspension of SAGM
55
55. What can we use donor red cells for?
* Red cells oxygen carrying capacity
* Symptomatic anaemia
* Exchange transfusion
* If significant bleeding anticipated, activate the major haemorrhage protocol
56
56. What does FFP contain? What is to given to patients for?
Fresh Frozen Plasma:
• FFP contains all clotting factors
• Given for coagulopathy with associated bleeding
57
57. 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?
• Only has 24 hour life after thawing (five days for major haemorrhage)
58
58. How are donor platelets given and for what?
* Adult pool of platelets from 4 donors (suspended in plasma from 1 donor)
* Platelets required to create clots to reduce bleeding (coagulation factors).
59
59. Why is patient history important for a platelet transfusion?
• Some drugs given to reduce efficacy of platelets (anti-platelet agents e.g. aspirin) so patient history important.
60
60. Why would you give Cryoprecipitate , how much should you give , how do you monitor it?
* Contains Factor VIII, VWF and fibrinogen
* 2 units usually given at one time
* Monitor fibrinogen levels by clotting screens
61
61. What are some regulations in place for blood transfusions/donors?
* EU Blood Safety Directive
* Blood Safety Quality Regulations
* Better Blood Transfusion 3
* MHRA inspections
* CPA inspections
62
62. What is Haemovigilance
set of surveillance procedures covering the entire blood transfusion chain
63
63. Explain the procedural aspects of haemovigilance?
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.
