blood tranfusion

Question 1

define blood group system

Answer 1

Collection of one or more RBC antigens under the control of a single gene or a cluster of closely linked homologous genes

Question 2

what factors determine the RBC antigens structure

Answer 2

specific sequence of oligosaccharides (3-10 monosaccharides in a chain)
specific sequence of amino acids

Question 3

how many blood group systems are there?

Answer 3

43

Question 4

43 blood group systems contains … antigens

Answer 4

345 red cell

Question 5

Which blood group systems are most clinically relevant

Answer 5

ABO and Rh

Question 6

Antibodies against RBC antigens cause haemolysis resulting in: (2)

Answer 6

haemolytic transfusion reactions (HTRs)

haemolytic disease of the foetus and newborn (HDFN)

Question 7

what are HTRs

Answer 7

where incompatible red cells are transfused i.e. transfused RBC has antigen that corresponds to patients plasma antibodies

Question 8

what is HDFN

Answer 8

where the foetus has a different RBC antigen to it’s mother where mother produces antibody to that RBC crossing the placenta.

Question 9

what are the two different types of antibodies?

Answer 9

naturally occurring antibodies

acquired alloantibodies

Question 10

describe ABO antibodies

Answer 10

.naturally occuring
.Their production is stimulated when the immune system encounters the ‘missing’ ABO blood group in foods or in microorganisms.
.ABO antibodies are mostly IgM antibodies that remain as IgM antibodies

Question 11

describe IgM antibodies

Answer 11

pentameric
The interaction between the pentameric IgM antibody and RBC antigens in vitro produces direct easily visualised clumping (agglutination) of red cells

Question 12

what can igM antibodies cause

Answer 12

acute HTRs through activation of the complement system resulting in massive intravascular haemolysis

Question 13

can igM antibodies cause HDFN?

Answer 13

No-igM can’t cross the placenta

Question 14

what causes acquired antibodies to form

Answer 14

.vaccination
.exposure from mother to foetus
.incompatiable blood transfusion

Question 15

what antibodies are associated with being acquired

Answer 15

IgG antibodies

Question 16

describe the structure of IgG antibodies

Answer 16

Y shaped

Question 17

true or false: IgG antibodies interaction with RBC antigens can’t be visualised in vitro

Answer 17

true

Question 18

what causes does IgG antibodies have

Answer 18

delayed HTR
Extravascular haemolytic
HDFN

Question 19

why can IgG antibodies cause HDFN but IgM cannot

Answer 19

IgG antibodies can cross the placenta in contrast to IgM which cannot.

Question 20

what does the A gene code for?

Answer 20

an enzyme that adds N-acetyl galactosamine (GalNac) to the common H antigen resulting in the A antigen

Question 21

what does the B gene code for?

Answer 21

enzyme that adds galactose (Gal) to the common H antigen resulting in the B antigen

Question 22

why can a transfusion of blood from the wrong ABO group be fatal

Answer 22

the PATIENT has anti A or anti B antibodies which activate complement to hamolyse the red cells

Question 23

what blood group is given in transfusion if type of patient is unknown and why?

Answer 23

O NEGATIVE- lacks both A or B antigens, therefore there is no risk of acute HTR occurring even if a patient has anti-A or anti-B antibodies.

Question 24

what is Landsteiner’s law

Answer 24

whichever ABO antigens are lacking on a given person’s RBCs, that person will always have the corresponding antibody. e.g B antigen patient has anti A (as there was no A in blood)

Question 25

when can platelets not of the same ABO blood group be given to a patient

Answer 25

when they are high-titre negative, (don't have a high concentration of anti A or Anti B antigens)

Question 26

A patient requires FFP or cyropercipitate but ABO is unknown. Which type may be given AND WHY

Answer 26

AB-HAS NO ANTIBODIES

Question 27

Which Rh antigen is most significant

Answer 27

D

Question 28

RhD, the D allele is recessive: true or false?

Answer 28

False-D allele is dominant

Question 29

Anti-D antibodies are clinically significant as they can cause:

Answer 29

``` Delayed HTRs (extravascular haemolysis) - if RhD positive red cells are transfused (resulting in anaemia, high bilirubin, jaundice) HDFN - if a RhD negative mother is carrying a RhD positive fetus as the IgG anti-D antibodies can cross the placenta and haemolyse the RhD positive fetal RBCs. ```

Question 30

how can we prevent formation of anti D antibodies

Answer 30

ensuring transfusions to RhD negative patients receive RhD negative red cells and platelets transfusions

Question 31

How are RhD pregnant women with RhD positive babies treated

Answer 31

Anti D-immunoglobulin which works by destroying any RhD positive fetal RBCs in the maternal (mum's) circulation before she can make her own anti-D antibodies (known as 'sensitisation')

Question 32

true or false: Red cells for transfusion should be of the same RhD type as the patient i.e. RhD negative RBCs for RhD negative patients.

Answer 32

true

Question 33

true or false: It is harmful to give a RhD positive patient RhD negative blood

Answer 33

False- no harm, just wasteful

Question 34

Group O RhD positive RBCs are used as emergency blood when a patient’s needs emergency transfusion: true or false?

Answer 34

false: Group O RhD NEGATIVE RBCs are used as emergency blood when a patient’s needs emergency transfusion

Question 35

define alloimmunity

Answer 35

Alloimmunity is an immune response to nonself antigens from members of the same species,

Question 36

true or false:Platelets for transfusion should be of the same RhD type as the patient i.e. RhD negative platelets for RhD negative patient

Answer 36

true

Question 37

FFP or cryoprecipitate of any D type can transfused regardless of the patients RhD type. Why?

Answer 37

These plasma components do not contain any RBCs.

Question 38

what is the forward group

Answer 38

ABO antigens on their RBCs

Question 39

what is the reverse group

Answer 39

ABO antibodies in their plasma

Question 40

define agglutination

Answer 40

formation of clumps of cells or inert particles by specific antibodies to surface antigenic components

Question 41

All blood donations undergo two types of testing:

Answer 41

group and screen | infection testing

Question 42

which tests are mandatory for donor blood

Answer 42

HIV,hep B,hep C, hepE,HLTV and syphillis

Question 43

what ADDITIONAL tests may be performed on donor blood

Answer 43

malaria, T.Cruzii, CMV (virus)

Question 44

what is the purpose of antibody screening

Answer 44

detect the presence of any acquired alloantibodies the patient may have developed. (antibodies produced from exposure to foreign RBC antigen)

Question 45

name two methods of blood donation

Answer 45

whole body donation | aphaeresis (machine collects and separates blood)

Question 46

what are the 4 main blood components?

Answer 46

Red cells (‘packed red cells’) Platelets Fresh Frozen Plasma (FFP) Cryoprecipitate

Question 47

what is fractionation

Answer 47

the pooling of plasma donations to form medicinal products

Question 48

what can plasma be fractioned into?

Answer 48

Human albumin solution Immunoglobulins Clotting factor concentrates

Question 49

what is FFP

Answer 49

FFP contains all the coagulation factors. Transfusions of FFP are required for treatment of bleeding or to reduce the risk of bleeding in patients with coagulopathies (multiple blood clotting factor deficiencies)

Question 50

what causes coagulopathies

Answer 50

.dilution ( massive bleeding) | consumption e.g Diseminated intravascular coagulation

Question 51

what is in cyroprecipitate?

Answer 51

contains fibrinogen, Factor VIII, von Willebrand factor and Factor XIII.

Question 52

clinical needs for Human albumin solution include:

Answer 52

To replace plasma volume in patients with plasma volume loss e.g. due to burns or trauma To replace plasma in plasma exchange e.g in the treatment of autoimmune disorders To initiate diuresis in patient with low albumin e.g. due to liver or kidney disease

Question 53

What do prothrombin complex concentrates contain

Answer 53

Factors II, VII, IX and X.

Question 54

PCCs can be used to reverse the effect of warfarin by replacing these deficient coagulation factors: true or false

Answer 54

True: PCCs can be used to reverse the effect of warfarin by replacing these deficient coagulation factors:

Question 55

PCC's can be used to treat:

Answer 55

major bleeding and haemorrhage