Week 4- Blood Transfusion

Question 1

What Ig class are antibodies?

Answer 1

IgM

Question 2

What antigens and antibodies do people with blood group O have? Who can they receive blood from and who can they donate to?

Answer 2

Antigens: none
Antibodies: Anti A+B

Can receive blood from: only group O
Can give blood to: all blood groups

Question 3

What antigens and antibodies do people with blood group A have? Who can they receive blood from and who can they donate to?

Answer 3

Antigens: A
Antibodies: Anti B

Can receive blood from: blood group A, O
Can give blood to: blood group A and AB

Question 4

What antigens and antibodies do people with blood group B have? Who can they receive blood from and who can they donate to?

Answer 4

Antigens: B
Antibodies: Anti A

Can receive blood from: B and O
Can give blood to: B and AB

Question 5

What antigens and antibodies do people with blood group AB have? Who can they receive blood from and who can they donate to?

Answer 5

Antigens: A+B
Antibodies: none

Can recieve blood from: AB, A, B, O
Can donate blood to: AB

Question 6

How do A and B blood antigens arise?

Answer 6

By adding a sugar residue to a glycoprotein on the RBC membrane

Question 7

What sugar residue is on an A antigen?

Answer 7

N acetyl galactosamine

Question 8

What sugar residue is on a B antigen?

Answer 8

Galactose

Question 9

What is the Rhesus system for blood?

Answer 9

There is a gene that codes for a D antigen on RBCs (dominant gene) so people are either rhesus positive (genotype DD or Dd) or rhesus negative (genotype dd)

Question 10

What antigens and antibodies do those who are rhesus positive have?

Answer 10

Antigens: D
Antibodies: none

Question 11

What antigens and antibodies do those who are rhesus negative have?

Answer 11

Antigens: none
Antibodies: none BUT that can make anti D antibodies if exposed to rhesus positive blood eg a rhesus negative mother who has a rhesus positive foetus

Question 12

What Ig class are anti D antibodies?

Answer 12

IgG

Question 13

What complications can arise if anti D antibodies are synthesized? Explain in the cases of future blood transfusions and pregnancy

Answer 13

Future blood transfusions: only rhesus negative blood can be given as positive has an antigen that the antibody will attack

Pregnancy: could be fatal for the foetus if the antibodies get into its blood (it’s blood has antigens the antibody will attack)

Question 14

How do we avoid synthesis of rhD sensitization (anti D synthesis)

Answer 14

In emergencies where blood type is not known transfuse using O neg, and transfuse blood of the same rhesus group if blood type is known

Question 15

What tests do blood samples undergo before transfusion? Describe how these tests are carried out

Answer 15

1. ABO compatibility: add anti A and anti B reagent
2. Rhesus compatibility: add anti D reagent
3. Antibody scan: a sample w all clinically relevant antigens is added, if there is no coagulation then blood is safe to transfuse. In the event of coagulation the antibody present in the blood must be identified and the donors blood should lack the corresponding antigen

Question 16

What antigens are tested for before transfusing a sample?

Answer 16

C, c, E, e and K

Question 17

How is infection avoided during transfusion?

Answer 17

Donors are pre selected to try to ensure they aren’t in the window period of developing an infection

Question 18

How are red cells stored for transfusion?

Answer 18

At 4 degrees in the fridge, with SAGM nutrients and plasma removed

Question 19

How is fresh frozen plasma stored?

Answer 19

At -30 degrees, has a shelf life of 3 years, must be thawed 20/30 mins before use

Question 20

When is fresh frozen plasma given?

Answer 20

Not to replace volume, when abnormal coagulation test results come back with excessive bleeding, reversal of warfarin eg if urgent surgery is required

Question 21

What is cyroprecipitate and how is it stored?

Answer 21

Fresh frozen plasma thawed overnight and just the residue remains stored. At -30 degrees, contains fibrinogen and factor VIII

Question 22

When is cryoprecipitate given?

Answer 22

When fibrinogen levels are low, there’s lots of bleeding

Question 23

What are the 2 ways platelet concentrates can be obtained?

Answer 23

1. Pooled donation from 4 different donors compiled to make one dose
2. A single donor providing the whole unit via attachment to a cell separator machine- this is equivalent to 4 donations

Question 24

How are platelet concentrates stored?

Answer 24

At room temp (22 degrees) and must be constantly agitated, shelf life of 7 days