Blood Transfusion Flashcards by Alaa M.

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)

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Erythrocytes (RBCs) have multiple _______ antigens attached to their cell surface

Erythrocytes (RBCs) have multiple glycoprotein antigens attached to their cell surface

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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

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Group A – have antigen __ attached to the erythrocyte cell surface

Antigen A

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Group B – have antigen ___ attached to the erythrocyte cell surface

Antigen B

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Group AB – have antigen _____ attached to the erythrocyte cell surface

Both antigen A and B

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Group O – have antigen ___ attached to the erythrocyte cell surface

Neither antigen

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Each person also has ____ antibodies in their plasma

Each person also has ABO antibodies in their plasma

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Function of ABO antibodies?

Recognise and attack RBCs expressing foreign antigens

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A and B antibodies are predominantly IgG/ IgM/ IgA/ IgD, and IgE

IgM

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Group A – have ____ antibodies

Anti-B

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Group B – have ___ antibodies

Anti-A

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Group AB – have ____ antibody

Neither

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Group O – have _____ antibodies

Both anti-A and anti-B

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Summary table (revision)

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What is the most immunogenic antigen?

Rhesus D - most likely to precipitate a transfusion reaction

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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

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Rh positive means..

Have the Rh D antigen and can receive both Rh+ and Rh- blood

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Rh negative means..

Lack the Rh D antigen and should only receive Rh- blood

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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 __

O and D group is dominant/silent

Silent

Genotype of RhD+

DD or Dd

Genotype of RhD-

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