Week 6 HRM - Transfusion

Question 0

What is serum?

Answer 0

The acellular component of blood left behind after clotting has occurred, meaning that it won’t contain fibrinogen or clotting factors

(It will contain nutrients, other proteins, gases, hormones etc)

Question 1

What are the two major blood groups involved in blood typing?

Answer 1

ABO and Rh

Question 2

What are naturally occurring antibodies?

Answer 2

These antibodies are present in a person which act against the antibodies of the blood type which they do not express. This applies to the ABO system
(I.e. Blood type A person will express natural antibodies to blood type B)

Question 3

On a molecular level, what determines s person’s ABO blood type?

Answer 3

The antigen consists of a string of sugars attached to the membrane and the type of sugar on the end of the chain determines what blood type.

Question 4

What antigens will someone with blood type O possess?

Answer 4

Naturally occurring antibodies for both A and B

Question 5

What are immune antibodies?

Answer 5

Develop after introduction of antigen to via transfusion or transplacental passage

Question 6

Why does matching of blood need to occur before transfusion?

Answer 6

So that there isn’t a haemolytic reaction that cause massive destruction of the blood cells, often fatal.

Question 7

What percentage of transfusions are safe purely based on matching the ABO and Rh blood type?

Answer 7

98% (further testing is done to make 100% sure that reaction will not occur)

Question 8

What is the proportion of Rh negative status, and how is Rh blood type determined?

Answer 8

Generally over 90% of Australians are Rh pos.

3 alleles contribute to the Rh group, and only if recessive for all 3 alleles will it be negative

Question 9

What diseases/infections are screened for in blood donations?

Answer 9

Hepatitis, HIV, syphilis, cytomegalovirus and T cell leukaemia virus I

Question 10

What is a direct Coombs test?

Answer 10

It is where RBCs are taken and incubated with anti human globulin, which if it binds and causes agglutination of the RBCs shows that there is antibodies bound to the RBC.

Question 11

What is an indirect Coombs test?

Answer 11

Using antibodies to see if there are any antibodies freely found in serum. Used to test pregnant women to see if they have antibodies for RhD.
Different to direct as it is detecting an immune response on RBC membranes

Question 12

What is anti human globulin?

Answer 12

Made by injecting animals with human globulin. They produce antibodies for human globulins. When you add them to a blood sample, if they bind to the blood cells or the antibodies, it shows that there is an immune reaction taking place.

Question 13

What is cross matching of the blood before transfusion?

Answer 13

Testing the RBCs of donor against the serum of the patient to see if any reaction takes place. Used to ensure no reaction takes place in blood transfusion where the donors have the same ABO and Rh groups.
(This is done after the ABO and Rh blood groups have been matched)

Question 14

What is the cause of the Rh D negative status?

Answer 14

The gene that encodes the Rh D protein may be absent from the genome, leading to an Rh- blood type. This is why when it is exposed to a Rh+ cell, it mounts an immune response against thenRhD antigen and antibodies form against it

Question 15

What is alloimmunisation?

Answer 15

The body’s immune response to interaction with a human cell/tissue. It is essentially immunity against a human derived antigen

Question 16

What is the most common immediate immune complication of blood transfusion?

Answer 16

Haemolytic reaction

Question 17

What are some of the non immunological complications immediately following transfusion?

Answer 17

Bacterial contamination
Circulatory overload
Hyperkalemia
Clotting abnormalities

Question 18

What occurs in a haemolytic reaction?

Answer 18

Intravascular haemolysis due to activation of IgM and IgG antibodies binding to the RBCs
Extravascular haemolysis occurs when Rh antibodies form, which is less severe but still can be life threatening.

Question 19

What are some delayed immunological complications associated with transfusion?

Answer 19

Delayed haemolytic reactions and alloimmunisation

Question 20

How could an allergic reaction occur following a transfusion?

Answer 20

The patient could be hypersensitive to donor plasma proteins which can result in anaphylactic shock

Question 21

What are some delayed non immunological complications following transfusion?

Answer 21

Infectious disease acquired through transfusion, including viruses, bacterial or parasites
Also can cause iron overload (only in repeated transfusion, chronic renal disease)

Question 22

When is transfusion of RBCs indicated?

Answer 22

When there is a need to increase oxygen delivery capacity in a short period of time

Question 23

What conditions usually require RBC transfusion?

Answer 23

Renal failure (lack of EPO)
Bone marrow failure
Some anemias
Thalassaemia
Sickle cell

Question 24

When should you transfuse platelet concentrate?

Answer 24

In severe thrombocytopenia

Question 25

What is cryoprecipitate?

Answer 25

Is frozen blood product prepared from plasma. Centrifuged from freshly thawed plasma. Contains fibrinogen and is used in aiding clotting.

Question 26

What is cryosupernant?

Answer 26

The component of plasma left after the cryoprecipitate is removed. Contains platelets and is also given to thrombytopenic patients. Also contains antibodies and can be used to help with passive immunity.

Question 27

What are the three categories of oxygen carriers that could potentially replace RBCs in transfusions?

Answer 27

1) perfluerocarbons
2) haemoglobin based oxygen carriers
3) engineered red blood cells

Question 28

What is haemolytic disease of the newborn?

Answer 28

The haemolytic reaction produced when the mother is Rh- and the baby is Rh+ leading to the Moree forming IgG antibodies against the baby’s RBCs. These cross the placenta and cause the destruction of the foetal RBCs