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Fundamentals of P > The Blood Transfusion Lab > Flashcards

The Blood Transfusion Lab Flashcards

1
Q

Describe characteristics of antibodies

A

Antibodies are protein molecules –immunoglobulins (Ig)
Usually of the immunoglobulin classes: IgG and IgM
Found in the plasma
Produced by the immune system following exposure to a foreign antigen

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2
Q

Reactions to blood usually occurs when?

A

Reactions to blood usually occurs when the antibody in the plasma reacts with an antigen on the cells

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3
Q

Blood group systems - how many and which ones most important

A

There are 26 known blood group systems

ABO and Rh are clinically most important

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4
Q

Effect of antigens in transfused blood on pt

A

Antigens in transfused blood can stimulate a patient to produce an antibody but only if the patient lacks the antigen themselves

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5
Q

Relation of antibody prod with transfusions

A

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

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6
Q

Describe ways to stim antibody prod

A

Blood transfusion
i.e. blood carrying antigens foreign to the patient

Pregnancy
Fetal antigen entering maternal circulation during pregnancy or at birth

Environmental factors
(i.e. naturally acquired e.g. anti-A and anti-B)

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7
Q

Effect of antigen-antibody reactions in vivo

A 
in vivo (in the body)
leads to the destruction of the cell either:

directly when the cell breaks up in the blood stream (intravascular)

indirectly when liver and spleen remove antibody coated cells (extravascular)

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8
Q

Agglutination - define

A

Agglutination is the clumping together of red cells into visible agglutinates by antigen-antibody reactions

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9
Q

Agglutination - cause

A

Agglutination results from antibody cross-linking with the antigens

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10
Q

List what agglutination can identify and what allows it to do this

A

As the antigen-antibody reaction is specific, agglutination can identify:-

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

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

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11
Q

ABO antibodies effect

A

ABO antibodies can activate complement causing INTRAVASCULAR HAEMOLYSIS

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12
Q

Group A -
RBC type
AB present
AT present

A

Group A -
RBC type = A
AB present = anti-B
AT present = A antigen

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13
Q

Group B -
RBC type
AB present
AT present

A

Group B -
RBC type = B
AB present = anti-A
AT present = B antigen

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14
Q

Group AB -
RBC type
AB present
AT present

A

Group AB -
RBC type = AB
AB present = none
AT present = A and B antigens

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15
Q

Group O -
RBC type
AB present
AT present

A

Group O -
RBC type = O
AB present = anti-A and anti-B
AT present = no antigens

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16
Q

Result for testing patient’s red cells with anti-A, anti-B and anti-D

A

agglutination shows that a particular antigen is on the red cells

no agglutination shows the antigen is absent

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17
Q

Result for testing patient’s plasma with A cells and B cells

A

agglutination shows that a particular antibody is in the plasma or serum

no agglutination shows the antibody is absent

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18
Q

ABO Compatibility - recipient blood group O

A

Only compatible with donor red cell O

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19
Q

ABO Compatibility - recipient blood group A

A

Only compatible with donor red cells O and A

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20
Q

ABO Compatibility - recipient blood group B

A

Only compatible with donor red cells O and B

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21
Q

ABO Compatibility - recipient blood group AB

A

Compatible with donor red cells O, A, B + AB

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22
Q

Rh grouping system - characteristics

A

50+ antigens:

Most important antigen is called D.

People with D antigen are D positive (85% of UK)

People who do not produce any D antigen are D negative (15%)

The other 4 main antigens are known as C, c, E and e

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23
Q

Rh (D) typing - conditions and result

A

Must be tested in duplicate (or tested each time and compared to historical result)

Patient / Donor classified as D pos or D neg

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24
Q

Clinical significance of Rh in transfusion

A

Transfusion

D antigen is very immunogenic and anti-D is easily stimulated - PREVENTION!

All Rh antibodies are capable of causing severe transfusion reaction- ANTIBODY DETECTION

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25
Q

Clinical significance of Rh in pregnancy

A

Pregnancy

Rh antibodies are usually IgG and can cause haemolytic disease of the newborn

Anti-D is still most common cause of severe HDN

26
Q

Development of Haemolytic disease of the Newborn (HDN)

A

Rh+ father

Rh- mother carrying first Rh+ fetus
- Rh antigens from developing fetus can
enter the mother’s blood during
delivery

Mother responds w/anti-Rh antibodies

If another Rh+ fetus, her anti-Rh antibodies will cross placenta + damage fetal RBC

27
Q

HDN – laboratory testing and result

A

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

28
Q

Describe quantification of atypical antibodies

A

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

29
Q

RAADP function

A

An injection of anti-D will bind to and remove any fetal D positive red cells in the circulation

30
Q

RAADP doses

A

1500 iu of anti-D is given routinely at 28 weeks and a smaller dose (usually 500 iu) after delivery if baby RhD+

In some hospitals 2 smaller (500 iu) doses are given at 28 and 34 weeks instead of the 1 larger dose

31
Q

List when Anti-D is also given

A

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

32
Q

Importance of screening antibodies that can cause haemolytic transfusion reaction

A

It is important that we screen for these antibodies

so that If detected, antigen negative blood can be provided to avoid causing a immune reaction.

33
Q

Antibody screening - process

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.

34
Q

If an antibody is detected we must:-

A

If an antibody is detected we must:-

Identify the antibody

Assess its clinical significance

  • For transfusion
  • In pregnancy
35
Q

How to 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

36
Q

Describe how IgG spanning the gap between RBCs is made possible

A

IgM antibodies can span the gap between RBCs
IgG can not, because too small to overcome ZETA potential (+ve charge)
LISS (low ionic strength saline) is negatively charged, so neutralises positive ZETA potential.
Therefore IgG can now span the gap.

37
Q

Explain formation of zeta potential

A

RBC surface = -vely charged due to the ionization of the carboxyl group of sialic acid

In saline RBC attract +vely charged Na+, and an ionic cloud will form around each cell

Thus the cells will be repelled and stay a certain distance apart.

ZP = measure of the difference in charge at the surface of the membrane and the outer edge of the ionic cloud (slipping plane).

38
Q

Indirect anti-globulin test (IAT) - describe action

A

LISS counteracts Zeta potential.

Results in agglutination

39
Q

Indirect anti-globulin test (IAT) - describe uses

A

Used for:

Used to detect IgG antibodies
Screening for antibodies
Identifying antibodies
Cross-matching donor blood with recipient plasma when there are known antibodies or a previous history of antibodies.

40
Q

Immediate spin cross-match (ISX) - describe process

A

Checking donor red cells against patients plasma
ABO check
Incubate for 2 – 5 minutes (room temp), spin and read.

41
Q

Immediate spin cross-match (ISX) - purpose

A

used to detect ABO incompatibility between donor red cells (RBCs) and the serum of the intended recipient.

42
Q

Immediate spin cross-match (ISX) - result

A

May be positive in the absence of ABO incompatibility (false positive)

or it may be negative when ABO incompatibility exists (false negative).

43
Q

Immediate spin cross-match (ISX) - used when

A

Antibody screen is negative

44
Q

Full Indirect Antiglobulin test (IAT) cross-match - used when

A

Antibody screen positive or patient has known antibody history.

45
Q

Full Indirect Antiglobulin test (IAT) cross-match - process

A

Select antigen negative donor red cells and incubate with patient serum for 15 minutes at 37oC

46
Q

RBC transfusion in what form

A

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

47
Q

What must be done after significant bleeding

A

If significant bleeding anticipated, activate the major haemorrhage protocol

48
Q

Fresh Frozen Plasma - composition

A

FFP contains all clotting factors

49
Q

Fresh Frozen Plasma - use

A

Given for coagulopathy with associated bleeding

50
Q

Fresh Frozen Plasma - requires what

A

Requires clotting screens to monitor

51
Q

Fresh Frozen Plasma - life length

A

Only has 24 hour life after thawing

five days for major haemorrhage

52
Q

Platelet transfusion in what form

A

Adult pool of platelets from 4 donors (suspended in plasma from 1 donor)

53
Q

Platelet transfusion - use

A

Platelets required to create clots to reduce bleeding

54
Q

Platelet transfusion - why pt history important

A

Some drugs given to reduce efficacy of platelets (antiplatelet agents) so patient history important

55
Q

Cryoprecipitate - composition

A

Contains Factor VIII, VWF and fibrinogen

56
Q

Cryoprecipitate - how many units used

A

2 units usually given at one time

57
Q

Cryoprecipitate - describe monitoring

A

Monitor fibrinogen levels by clotting screens

58
Q

List the aspects of regulation of Blood

A 
EU Blood Safety Directive
Blood Safety Quality Regulations
Better Blood Transfusion 3
MHRA inspections
CPA inspections
59
Q

Serious Hazards of Transfusion (SHOT) - describe action required

A

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

60
Q

Serious Adverse Blood reactions and events (SABRE) - describe action required

A

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

Fundamentals of P (62 decks)

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