Rhesus Blood Groups Flashcards
What is the most important antigen in the Rhesus System?
The D antigen.
What are the blood groups in the Rhesus System?
RhD positive or RhD negative RhC positive or RhC negative RhE positive or RhE negative RhKell positive or RhKell negative RhDuffy positive or RhDuffy negative RhKidd positive or RhKidd negative
What are the alleles in the Rhesus group?
Follows this pattern: ie for RhD positive D gene codes for D antigen on RBC membrane, for RhD negative d gene codes for no antigen and is recessive.
What is the genotype for RhD negative?
Dd or DD
Is RhD positive or negative more common?
RhD positive.
How do RhD negative people make anti-D antibodies?
They can make it after they are exposed to RhD positive blood. This can happen either by transfusion, or in women pregnant with a RhD positive foetus.
What Ig class antibodies are anti-D antibodies?
IgG class antibodies
What precautions must you take with patients that have developed anti-D antibodies?
All their future transfusions need to be with RhD negative blood.
What happens if someone with anti-D antibodies has RhD positive blood transfused to them?
The anti-D antibodies would react with RhD positive blood- causes delayed haemolytic transfusion reaction:
- with anaemia
- high bilirubin (from breakdown of red cells)
- jaundice
- among other acute symptoms
What would happen if a RhD negative mum has a RhD positive baby, and then becomes pregnant with another RhD positive baby?
Haemolytic Disease of the Newborn HDN) -
If RhD negative mum has anti-D antibodies (from the first pregnancy),
then the mother’s anti-D antibodies can cross the placenta-
attach to RhD positive red cells of the foetus and cause haemolysis is of foetal red cells-
if severe can cause hydrous fetalis and death.
If less severe, the baby will survive birth but the high bilirubin levels can cause brain damage or death.
What is a key aim with RhD negative patients?
Avoid sensitisation of RhD negative patients with RhD positive blood.
Transfuse blood of the same RhD group as the patient.
What do you do if you need to do an emergency blood transfusion but you don’t know the patient’s blood type?
Use type O negative blood.
- used in emergencies.
- however: only 6-7% of donors are O-negative.
