Blood Transfusion Flashcards
Blood typing is a method of classifying blood into different blood groups depending on..
Presence of different antigens on the surface of red blood cells (RBCs)
Erythrocytes (RBCs) have multiple _______ antigens attached to their cell surface
Erythrocytes (RBCs) have multiple glycoprotein antigens attached to their cell surface
An individual inherits one _____ allele from each parent, with _____ and _____ alleles being co-dominant and producing the _____ and _____ antigens respectively
An individual inherits one ABO allele from each parent, with A and B alleles being codominant and producing the A and B antigens respectively
Group A – have antigen __ attached to the erythrocyte cell surface
Antigen A
Group B – have antigen ___ attached to the erythrocyte cell surface
Antigen B
Group AB – have antigen _____ attached to the erythrocyte cell surface
Both antigen A and B
Group O – have antigen ___ attached to the erythrocyte cell surface
Neither antigen
Each person also has ____ antibodies in their plasma
Each person also has ABO antibodies in their plasma
Function of ABO antibodies?
Recognise and attack RBCs expressing foreign antigens
A and B antibodies are predominantly IgG/ IgM/ IgA/ IgD, and IgE
IgM
Group A – have ____ antibodies
Anti-B
Group B – have ___ antibodies
Anti-A
Group AB – have ____ antibody
Neither
Group O – have _____ antibodies
Both anti-A and anti-B
Summary table (revision)
What is the most immunogenic antigen?
Rhesus D - most likely to precipitate a transfusion reaction
The presence or absence of Rh D antigen on the erythrocyte cell surface determines whether..
The person has Rh positive (Rh+) or Rh negative (Rh-) blood groups
Rh positive means..
Have the Rh D antigen and can receive both Rh+ and Rh- blood
Rh negative means..
Lack the Rh D antigen and should only receive Rh- blood
Rh negativity is generally more prevalent in ________ populations (15%), than ________ (8%) and ________ (1%) populations
Rh negativity is generally more prevalent in Caucasian populations (15%), than Afro-Caribbean (8%) and Asian (1%) populations
Anti-D antibody is usually absent in Rh- patients until..
They have been exposed to Rh+ erythrocytes
Rh- patients should not be transfused with Rh+ blood as this can cause them to develop..
Anti-D antibodies. This may cause transfusion reactions in the future
Explain the rhesus incompatibility in pregnancy
Can lead to Haemolytic Disease of the Newborn (HDN)
Anti-D injections should also be given at any time where sensitisation may occur, such as..
Antepartum haemorrhage
Amniocentesis procedures
Abdominal trauma
Anti-D injections are given routinely on two occasions..
28 weeks gestation
Birth (if the baby’s blood group is found to be rhesus-positive)
What does the Kleinhauer test do and when is it done?
To see how much fetal blood has passed into the mother’s blood + determine whether further doses of anti-D are required
After 20 weeks gestation
How is the Kleinhauer test done?
- Adding acid to a sample of the mother’s blood
- Fetal haemoglobin is naturally more resistant to acid, so that they are protected against the acidosis that occurs around childbirth, while mothers haemoglobin is destroyed
- The number of cells still containing haemoglobin (the remaining fetal cells) can then be calculated
A person should NOT receive blood products containing antigens for which they have the..
Corresponding antibodies
Transfusing an incompatible blood type will precipitate a..
Fatal transfusion reaction as the recipient’s ABO antibodies attack the donor’s antigen (seen as foreign)
How to minimise blood transfusion complications?
Frequently monitored, particularly at the start of each unit.
Which blood group are considered as universal donors and why?
O group - this is because their RBCs have no A, B, or RhD antigens which the recipient’s immune system could attack
Which blood group are considered as universal recipients?
AB+ - their plasma does not contain anti-A, anti-B, or anti-D antibodies, so they will usually not mount an immune response to the donor blood
What is Direct Antiglobulin Testing (DAT)?
Detects whether a patient’s RBCs have antibodies directly attached to them
Coombs’ reagent binds to specific immunoglobulins on the RBCs. It is added to the patient’s blood. A positive test results in the RBCs agglutinating (clumping together)
A positive DAT indicates that..
Haemolysis has an immune aetiology, causes include autoimmune haemolytic anaemia, haemolytic transfusion reactions, and HDN
What is Indirect Antiglobulin Testing (IAT)?
Detects antibodies present in the patient’s plasma. This can be used in cross-matching or to detect maternal anti-D IgG
Donor’s RBCs and Coombs’ reagent is combined with the patient’s isolated plasma. Test is positive if agglutination occurs
What does a positive IAT indicate?
Patient has antibodies against the antigens present on the donor’s RBCs
What are the blood components?
Red cells, FFP, platelets, cryoprecipitate
What are the blood products?
Anti-D immunoglobulin, prothrombin complex concentrate
What are the blood products from pharmacy?
IV immunoglobulin, human albumin, specific Ig
How does blood processing occur?
ABO occurs on chromosome __
9
O and D group is dominant/silent
Silent
Genotype of RhD+
DD or Dd
Genotype of RhD-
dd
Identify ABO and RhD group of a patient using..
When is blood transfusion indicated?
Symptomatic anaemia Hb<70g/L (80g/L if cardiac disease)
Major bleeding
Always consider cause before transfusion - is there an alternative?
When is platelet transfusion indicated?
Prophylaxis in patients with bone marrow failure and very low platelet counts
Treatment of bleeding in thrombocytopenic patient
Prophylaxis prior to surgery/ procedure in thrombocytopenic patient
When is FFP transfusion indicated?
Treatment of bleeding in patient with coagulopathy (PT ratio >1.5)
Prophylaxis prior to surgery or procedure in patient with coagulopathy (PT ratio >1.5)
Management of massive haemorrhage
Transfuse early in trauma
T or F: FFP transfusion is used in the absence of bleeding/ planned procedure
True
