Blood groups and transfusion Flashcards
How is ones blood group determined
- Sugar residues form the ABO blood group type
- Proteins for the rhesus blood group type
- Your genes determine which sugar/ protein is expressed and therefore your blood group
Where are blood groups lcoated
On the surface of the cell- red cell surface has lipid bilayer containing sugar and protein residues
What are red cell antigens
Substances on the surface of a red cell that can stimulate the formation of antibodies
What are autoantibodies
React with antigens present on a persons own red cells
What are alloantibodies
Produced by the person against antigens not present on own red cells
How does agglutination work
- Red cells express antigens
- Antibodies to that antigen bind red cells together via antigens
- Causes cell destruction
What kind of antibodies are ABO antibodies
IgM and IgG (mostly G)
Why are IgM antibodies known as cold acting
They bind at room temp
What antibody does blood group A contain in plasma
anti-b
What antibody does group group B contain in plasma
Anti-a
What antibody does blood group O contain in plasma
Anti-a and Anti-B
What antibody does blood group AB contain in plasma
No ABO in plasma
What are the possible genotypes for phenotype blood group A
AA, AO
What are the possible genotypes of phenotype blood group B
BB, BO
What are the possible genotypes for phenotype AB
AB
What are the possible genotypes for phenotype O
OO
Name the blood groups in order of frequency amognst caucasian people
A,O, B, AB
Name the blood groups in order of frequency amongst asian people
B, A, 0, AB
Which blood type is the universal donor and why
Group O because they have no antigens and plasma is not donated in great quantities
If patient is group a, who can donate
A or O
If patient is group b who can donate
B or O
If patient is group AB who can donate
ab, a, b or o
If patient is group O who can donate
O
What kind of antibodies are involved in Rh blood group
Immune antibodies- only exposed if person exposed to antigen through transfusion, pregnancy or transplantation
What antigens are involved in Rh blood groups
C/ c
D or no D (no D is written as d)
E or e
How are the antigens in Rh blood groups inherited
As a triplet
What will agglutinate CcDe
anti-C, anti-c, anti-D and anti-e
What will agglutinate cdE
anti-c, anti-E
Which antigen is the most important in Rh, and why
D antigen
80% of people without the D antigen will develop anti-D if exposed to it
How may phenotype CcDEe be inherited
- CDe/ cDE
- CDe/cdE
- cDE/ Cde
- CDE/cde
What determines rhesus positive/ negative
Presence or absence of D antigen
How is phenotype Ccde inherited
Cde/cde
How is phenotype cde inherited
cde/cde
Is it more common to be rhesus positive or negative
Positive
Which pregnancy will haemolytic disease of the foetus and newborn affect
Second child
How does haemolytic disease of the foetus and newborn come about?
- Rhesus (D) negative mother carries rhesus (D) positive baby
- Immune system is sensitised to D antigen
- Second rhesus (D) positive child– there is now anti-D antibody which is stimulated, crosses placenta and destroys foetal red cells
How is haemolytic disease of the foetus and newborn now managed
All rhesus (D) negative mothers get prophylactic anti- D in first pregnancy
Can you give Rh(D) negative donor to a Rh (D) positive patient?
Yes
What is removed in a red cell transfusion
Unit with the most plasma is removed
What is removed in a red cells in additive solution
Unit with most plasma, white cells and platelets removed
When may a red cell transfusion be required
- Blood loss
- Bone marrow failure
- Haemolysis
- Inherited Hb disorders
Should you do a red blood transfusion if anaemia is present due to iron/ B12 or folate deficiency?
Should be avoided if poss- instead give haematinic replacement therapy
What are the potential risks of giving blood
- infection
- alloimmunisation
- incompatable transfusion
- circulatory overload
- iron overload
Why is an indirect antiglobulin test done
To screen for atypical antibodies in patients plasma
How is an indirect antiglobulin test carried out?
- Patients plasma mixed with group O cells expressing all the common blood group antigens
- If antibody present, will bind to antigens on detector cells
What must be monitored during a transfusion
Pulse, BP, temp
What are the symptoms of a possible transfusion reaction
Restless, flushing, anxiety, abdo pain, nausea and diarrhoea, pain at venopuncture site
What are the signs of transfusion reaction
Fever, hypotension, haemoglobinguria
Rapid temp spike >40 degrees
How do you manage a possible transfusion reaction
Stop transfusion
Maintain venous access with saline
Commence resus
Most common reason for incompatability
Patient wrongly identifed
When do symptoms of delayed haemolytic transfusion reaction occur
7-10 days post transfusion
Why does delayed haemolytic transfusion reaction occur
Failure of Hb to rise
