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Flashcards in Blood Groups and Transfusion Deck (20)
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1
Q

What are some examples of red cell antigens

A

ABO, Rhesus (which are the most important) and then Kell, Duffy, Kidd, MNS which are less likely to cause clinical issues

2
Q

Describe the mechanism of immune haemolysis for IgM

A

These can be pentameric so have many binding sites that can bind to many cells. They then cause the breakdown of RBC’s rapidly in the circulation

3
Q

Describe the mechanism of immune haemolysis for IgG

A

These antibodies bind to individual cells and then circulate into the liver and spleen where they are recognised by macrophages which can then destroy the cell.

4
Q

What genes code for the H substance and what chromosome are these found on?

A

FUT1 and FUT2 genes which are found on chromosome 19

5
Q

What genes code for glucosyl transferases, what chromosome are these on and what is the function of these?

A

A and B genes found on chromosome 9. The function of glucosyl transferases is to bind to the H substance adding another sugar to the chain, this determines whether the blood is A, B or O

6
Q

What sugars make the blood type B or A

A

B - Galactose

A - N -acetlygalactosamine

7
Q

For each blood group what are the RBC surface antigens and the naturally occurring antibodies

A

Group O no antigens and anti-A and anti-B antibodies. Group A has A antigens and Anti-B antibodies. Group B has B antigens and Anti-A antibodies. Group AB has both A and B antigens so doesn’t produce any antibodies

8
Q

What is the Rhesus system?

A

They are another group of antigens on the surface of the RBC consisting of c, C, D, e, E. People will inherit a triplet of these antigens, eg, cDe

9
Q

What does it mean to be Rhesus positive or Rhesus negative

A

This refers to the D antigen which is the most common. So if you have the D antigen then you are Rhesus positive and if you don’t have the D antigen then you are Rhesus negative.

10
Q

Describe the haemolytic disease of the newborn

A

Foetal red cells carry antigens from the father that the mum does not have, these cells transfer to the mothers circulation and so the mother produced IgG antibodies against the antigen on foetal RBC’s. The antibodies cross the placenta and cause anaemia, jaundice, brain damage or foetal death.

11
Q

Describe the prevention of rhesus D immunisation (HDN)

A

Anti-D prophylaxis is given to D negative mothers at 28 weeks and delivery and after obstetric events.

12
Q

What test looks for foetal cells in the mothers circulation?

A

Kleihauer test

13
Q

Describe some methods of foetal monitoring

A

This is where the mother is monitored for the development antibodies. You can monitor the baby via ultrasound by looking at flow in middle cerebral artery (in anaemic then flow rate will increase), looking for ascites (free fluid in abdo) and also looking at liver and spleen size. Can also do umbilical cord sampling

14
Q

What can umbilical cord sampling tell you

A

Blood count, blood group and antibody level

15
Q

What is the neonatal management of HDN

A

Clinical assesment, blood tests (reticulocytes, group, RBC antibodies and bilirubin), Coombes test, allow the antibodies to decline, phototherapy to increase bilirubin conjugation and top up transfusion or exchange transfusion.

16
Q

How can you cross-match blood?

A

Donor blood checked for ABO, rhesus D, other antigens and screened for HIV or hepatitis etc. Then recipient’s blood checked for ABO, rhesus D and plasma is screened for antibodies against red cell antigens. Finally recipient’s plasma is mixed with donor RBC’s to check for agglutination.

17
Q

What is a Coombs test?

A

Used to detect antibodies that act against the surface of your RBC’s

18
Q

What is agglutination?

A

The clumping of particles. In blood this occurs if the antigen is mixed with its corresponding antibody

19
Q

What occurs in transfusion reactions?

A

Acute haemolytic reactions due to miss-matched blood. Delayed haemolytic reactions, Urticaria (hives) or anaphylaxis and febrile reactions (fever and chills due to antibodies reacting with WBC antigens).

20
Q

What are some of the errors in transfusion?

A

Failure to establish identity/ incorrectly labelling tube. Lab errors and failure to preform bedside check of identity when administering blood.