Haematology 10: Blood Transfusion Flashcards
List major blood groups
- ABO Blood Groups
(common stem = H antigen)
A gene + common stem
B- GAL + common stem
What is the shelf life of blood?
5 weeks
On the RBC cell membranes, we all have a common __________
H stem
In blood group O:
Common stem Y/N
A antigens Y/N
B antigens Y/N
In blood group O:
Common stem =Y
A antigens = N
B antigens = N
In blood group A:
Common stem Y/N
A antigens Y/N
B antigens Y/N
In blood group O:
Common stem =Y
A antigens = Y
B antigens = N
In blood group B:
Common stem Y/N
A antigens Y/N
B antigens Y/N
In blood group O:
Common stem =Y
A antigens = N
B antigens = Y
How are A + B antigens formed?
- add 1+ sugar residues onto common glycoprotein + fructose stem on RBC membrane
What does A gene code for?
A gene:
- codes for enzyme that adds N-acetyl galactosamine
–> onto common glycoprotein + fructose stem
What does B gene code for?
B gene:
- codes for enzyme that adds galactose
–> onto common glycoprotein + fructose stem
A + B genes are
Dominant / Recessive / Codominant
A + B genes are
Codominant
A + B genes are
Dominant / Recessive / Codominant
A + B genes are
Codominant
O gene is
Dominant / Recessive / Codominant
O gene is
Recessive
Blood group A
Antigens on RBC =
Antibodies in plasma =
Blood group A
Antigens on RBC = A
Antibodies in plasma = Anti B
Blood group B
Antigens on RBC =
Antibodies in plasma =
Blood group B
Antigens on RBC = B
Antibodies in plasma = Anti A
Blood group O
Antigens on RBC =
Antibodies in plasma =
Blood group O
Antigens on RBC = Nil
Antibodies in plasma = Anti A + Anti B
Blood group AB
Antigens on RBC =
Antibodies in plasma =
Blood group AB
Antigens on RBC = A + B
Antibodies in plasma = Nil
How do you test blood groups?
- Blood sample taken from patient
- ABO group determined
- select donor unit of the same group
- carry out X match
What is X match
patient’s serum = mixed with donor RBC
- if it reacts –> shows that it is incompatible
- shouldn’t react
How does O -ve and AB +ve differ
O -ve = safe for everyone
AB +ve = can only be given to other AB +ve
How does RhD +ve and RhD
-ve differ?
RhD +ve:
- you have D antigen
- no antibodies
RhD -ve:
- you don’t have D antigen
- can make anti-D antibodies if sensitized
Note
Anti-D antibodies = IgG antibodies
What are some implications of Anti-D antibodies?
- when needed, RhD -ve blood individuals need to get RhD -ve or else anti-D will reacts with RHD pos blood
- -> causing anaemia, high BR, Jaundice
- HDN
- HAEMOLYTIC DISEASE of the newborn
- if RHD -ve mother has antiD, in next pregnancy –> so fetus i post RhD possible causes haemolysis of fetal red cells
- avoid RhD -ve patients making anti-D
- you need to transfuse blood of the same RhD blood group
- O -ve = used as emergency blood when patient’s blood group is not know
Why is whole blood no longer given to patients?
- it is more efficient to give parts because patients may not need all the components
- some components degenerate quickly if stored as whole blood (e.g blood in fridge = not good for coagulation factors)
- prevent fluid overload
How do you collect blood?
- 1 pint of blood = collected into bag with anticoagulant
- RBC = concentrated
- Plasma = removed (allows you to avoid fluid overloading patients)
- split 1 unit of blood by centrifuging the bag
- Blood splits up into components
- each layer = squeezed into satellite bags –> cut free
- entire system = closed
