Blood Groups and Transfusions

Question 1

Blood Groups and Blood Transfusions

Answer 1

Blood Groups:
-Antigens (Ags) are found on the surface of RBCs
-Function of blood groups is not always clear, but it is
important in transfusion medicine
-Over 400 different blood groups have been describe,of these ABO and Rh systems are important

Blood transfusion:

• Infusion of a blood product
• Important form of treatment
• Compatibility of blood groups between the donor and the patient (recipient) is NB to avoid haemolytic transfusion reactions

Question 2

ABO Blood Groups

Answer 2

Discovered in 1901 by Karl Landsteiner

The ABO antigens are carbohydrates

The basic substance is the H antigen (Ag)
-A, B and H antigens on red cells are predominantly glycoproteins

Majority are present on the N-glycans of the anion
exchanger (band 3) and the glucose transporter

The A, B and O genes are alleles of each other on
chromosome 9

80% of the population also have secretor genes which
secrete ABO Ags into saliva, etc.

The ABO gene is located on the long arm of chromosome 9

Encodes for glycosyltransferase enzymes

A allele codes for a GalNActransferase enzyme:
-Adds N-acetyl-galactosamine to the H substance

B allele codes for a Gal-transferase enzyme:
– Adds galactose to the H substance

O allele: similar to A allele but has a single base deletion in exon 6, so that no glycosyltransferase enzyme is produced

Question 3

Blood Group A

Answer 3

The A allele codes for an enzyme that adds N-acetylgalactosamine to the H substance to form the A Ag

Question 4

Blood Group B

Answer 4

The B allele codes for an enzyme that adds galactose to

the H substance to form the B Ag

Question 5

Blood Group O

Answer 5

The O allele does not code for an enzyme. Nothing is
added to the H substance, therefore the O antigen consists of only the H substance

ABO BLOOD GROUPS
• Definitions of Genotype and Phenotype
– Genotype:
• Genetic constitution of an individual person
– Phenotype:
• The physical or biochemical characteristics of a
person reflecting genetic constitution, posttranscriptional and post-translational modifications
and environmental influence
• ABO blood groups are inherited in a co-dominant fashion

Question 6

ABO Blood Groups:

Genotype vs Phenotype

Answer 6

Genotype:
-Genetic constitution of an individual person

Phenotype:
-The physical or biochemical characteristics of a person reflecting genetic constitution, posttranscriptional and post-translational modifications
and environmental influence

ABO blood groups are inherited in a co-dominant fashion

Question 7

ABO Blood Groups

Answer 7

Clinical importance of a blood group system in blood
transfusion lies in frequency of its antibodies and in
possibility that such antibodies will destroy incompatible
cells in vivo

ABO system was the first to be recognized and remains the most NB

Reason: almost everybody over age of +/- 6 months has clinically significant anti-A and/or anti-B in their serum if they lack the corresponding antigens on their red cells

ABO antibodies arise in response to A- and B-like antigens present on bacterial, viral or animal molecules

Due to this cross-reaction between the Ags of e.g. gut
bacteria and blood groups, IgM Abs are produced against those blood group Ags that are foreign to that person:

• Blood group O: anti-A & anti-B
• Blood group A: anti-B
• Blood group B: anti-A
• Blood group AB: no anti-A or anti-B

These IgM Abs may cause intravascular, complement
mediated, haemolysis when incompatible blood is
transfused

Unique in that it is the only blood group system where
reciprocal or antithetical Abs are present with no prior
exposure to Ag

“Naturally occurring” antibodies

Reason why ABO compatibility is so important in
transfusion testing

Provide the tools for ABO testing

Question 8

ABO Compatibility

Answer 8

IgM is a pentamer

IgM ABO antibodies cause agglutination of RBCs carrying the corresponding ABO blood group antigen

Donors Recipients:
O neg = “universal donor”
AB pos = “universal recipient”

Question 9

RH Blood Group System

Answer 9

In 1940, Karl Landsteiner and Alexander S. Wiener reported a serum that reacted with +/- 85% of different human RBCs

Serum was produced by immunizing rabbits with
RBCs from Rhesus macaque monkeys

Antigen that induced this immunization was designated by them as Rh factor “to indicate
that rhesus blood had been used for the
production of the serum.”

Second most important system

Major antigen: D-Antigen
– Rh positive ( D+) 85%
– Rh negative ( D-) 15%

D Ag is highly immunogenic

Antibodies are “unexpected” and are immune - they result from previous transfusion or pregnancy

Three closely linked gene loci:
– Define the 5 major Ags: D, C, E, c, e.
– D or “no D” is inherited at one locus
– C or c is inherited at a second locus
– E or e is inherited at a third locus

D is the most important Ag
• – presence of D Rh positive
• – absence of D Rh negative (No D

Question 10

Inheritance

Answer 10

ABO & RH genes are not linked

ABO & Rh(D) type are inherited independently

For example:
An A Rh(D) pos mother and a B Rh(D) pos father
could have an O Rh(D) neg child

Question 11

RH Inheritance

Answer 11

The 5 major Ags are inherited as haplotypes(one gene complex) from each parent.
-Cde from the mother and the cde from the father>Cde/cde

Question 12

RH Antibodies

Answer 12

Anti-Rh antibodies only occur in Rh-negative people after exposure to Rh-positive blood through:
– Blood transfusion
– Pregnancy

Anti-Rh antibodies are IgG (small Abs)
– It crosses the placenta
– It cannot agglutinate RBCs

Importance of this blood group is that it can cause
Haemolytic disease of the foetus & newborn (HDFN)

Can also cause delayed haemolytic transfusion reactions

Question 13

Unexpected/Immune Allo-Antibodies

Answer 13

Need understanding

Question 14

How is ABO and Rhesus Grouping Done

Answer 14

Patient’s red cells with anti-A and anti-B Antisera (forward grouping)

and

Patient’s plasma for the presence of anti-A and anti-B
against reagent A and B cells (reverse grouping)

This test is done at room temperature and a positive reaction is determined by agglutination of the red cells.

Question 15

Haemolytic Disease of the Foetus and Newborn(HDFN):

Definition

Answer 15

Shortened life span of foetal/neonatal RBC due to destruction by maternal antibodies

Question 16

Haemolytic Disease of the Foetus and Newborn(HDFN):

Pathophysiology

Answer 16

When:
– Mother: Rh negative
– Foetus: Rh positive

First pregnancy:
– Foetal cells enter mother’s circulation
– Mother produces anti-D antibodies
– Clinically no problems

Second pregnancy:
– Prompt anamnestic response
– IgG anti-D cross placenta and coat foetal red cells
– Red cells removed by foetal RE system
– Haemolytic disease of the foetus & newborn
– HDFN may also be caused by ABO incompatibility with IgG Abs

Common blood group mismatches:

Antigen-antibody reaction leads to haemolysis in foetus/newborn:
– Anaemia
– Hyperbilirubinaemia

Question 17

Haemolytic Disease of the Foetus and Newborn(HDFN):

Clinical Picture

Answer 17

Mild:
Jaundice-Acummulation of unconjugated bilirubin

Severe:
Anaemia-Destruction of red blood cells
Kernicterus-Bilirubin deposition in the basal ganglia and as a result brain damage is caused by the hyperbilirubinemia as the bilirubin moves form the blood to the brain tissue.

Question 18

Haemolytic Disease of the Foetus and Newborn(HDFN):

Laboratory Diagnosis

Answer 18

1. Haematology
2. Immunology
3. Chemistry

Question 19

Haemolytic Disease of the Foetus and Newborn(HDFN):

Laboratory Diagnosis-Haematology

Answer 19

FBC:

• Anaemia (Hb low for age!)
• Differential count: many NRBCs
• Erythroblastosis foetalis
• Instrument unable to generate DIFF
• NRBC’s counted as lymphos

Peripheral smear:
-NRBCs, polychromasia, spherocytes
-Difficulty: normal neonates can have NRBCs &
polychromasia!!

Question 20

Haemolytic Disease of the Foetus and Newborn(HDFN):

Laboratory Diagnosis-Immunology

Answer 20

Local Lab:
1. Is there an antibody present?
– Coombs test: direct & indirect

2. Against what antigen is it directed?
   – Blood group testing (ABO, Rh for mother & baby)
   Reference Lab:

Specificity
3. How strong is the antibody?
– Titre

Question 21

Haemolytic Disease of the Foetus and Newborn(HDFN):

Laboratory Diagnosis-Chemistry

Answer 21

Hyperbilirubinaemia

Question 22

Haemolytic Disease of the Foetus and Newborn(HDFN):

Treatment

Answer 22

Depends on severity of haemolysis & jaundice:

– Phototherapy (UV lights) to solubilise the bilirubin

– Exchange transfusion with Rh-neg RBCs

Question 23

Haemolytic Disease of the Foetus and Newborn(HDFN):

Prevention

Answer 23

All pregnant women:
– Blood group (ABO & Rh)
– Screening for preformed antibodies (indirect Coombs)

All Rh- women:
– Anti-D prophylaxis after birth of Rh+ baby - destroys the Rh-pos baby cells before an immune response is
launched

Question 24

Other Blood Groups

Answer 24

These are not as immunogenic or NB as Rh & ABO blood groups

Most NB: Kell, Lewis, MN, P, Ii, Duffy

Cause problems in patients with multiple transfusions

May also be involved in HDN

Question 25

Blood Transfusions

Answer 25

All blood in South Africa is collected from non-remunerated voluntary donors • Screened via comprehensive donor questionnaire so that only those at lowest risk for transfusion transmissible infections (TTIs) are allowed to donate • Transfusion transmissible pathogens of concern in SA: – Human Immunodeficiency virus (HIV) – Hepatitis B virus – Hepatitis C virus – Treponema Pallidum (syphilis) – Other bacteria – Malaria parasites SAFETY OF THE BLOOD SUPPLY • Every single unit collected in SA is TESTED for the presence of – Hepatitis B & C – Syphilis – HIV 1 & 2, (window period NB) • Donors are ABO, Rh typed • Blood is crossmatched for ABO & Rh • Patient tested for other Abs that may cause haemolysis • Check that the right patient gets the right blood product for the right indication at the time SAFETY OF THE BLOOD SUPPLY • Specific tests: – Hepatitis B surface antigen – Hepatitis C antibody – HIV 1 and 2 antibodies – Syphilis – Nucleic Acid Amplification testing for HIV 1, HBV and HCV • All reactive units are removed from quarantine and carefully disposed of • Further confirmatory tests are performed; donors subsequently notified and deferred • The addition of NAT-testing has significantly reduced the window period for HIV, HBV and HCV SAFETY OF THE BLOOD SUPPLY • Look back programme • Initiated in 1985 by blood transfusion services to assess the incidence of transfusion-transmitted infection • Programme traces any patient who received HIV and Hepatitis negative blood from a donor whose subsequent donation is found positive for either infection • Patients are contacted through the hospital or their private physician and are offered counselling and testing ADDITIONAL SAFETY MEASURES • Where the applicable technology exists, blood product is further treated to inactivate any latent infection • Currently the following products undergo viral inactivation procedures or include steps as part of the manufacturing process that have been documented as viral reduction steps: – Albumin – Stabilised Serum – Factor VIII and IX concentrates – Immunoglobulins – Fresh Dried Plasma (FDP)

Question 26

Components

Answer 26

``` Leucocytes, platelets & clotting factors do not survive for long in donated blood • Thus donated blood is centrifuged and components separated: • Packed red cells: – To increase oxygenation when this is critically reduced by anaemia or haemorrhage • Platelets: – To replace deficient or dysfunctional platelets resulting in significant haemostatic problems • Fresh frozen plasma: – Scoline apnoea – To correct haemostatic disorders associated with: • Clotting factor deficiencies (e.g. DIC) • Reversal of life threatening Warfarin effects • TTP (Cryosupernatant) • Collected into a top and bottom bag • Primary collection bag contains anticoagulant (CPD) and has an empty transfer bag connected to top • Another transfer bag containing optimal additive solution (SAGM) is connected to bottom • After centrifugation plasma is expressed out of top and red cells out of bottom leaving buffy coat in primary collection bag • Components obtained: – Red cell concentrate in bottom bag – Buffy coat layer of white cells and platelets in primary bag – Plasma in top transfer bag ```

Question 27

Components: Red Cell Concentration

Answer 27

Keep at 4-10°C Shelf life: 35-42 days

Question 28

Compoents: Platelets

Answer 28

Keep at room temperature Shelf life: 5 days

Question 29

Components: Fresh Frozen Plasma

Answer 29

Keep at at least -18°C (Shelf life: 3 months) If stored at -25 °C: Shelf-life = 3 years

Question 30

Alternative Procedures to Allogeneic Blood Donation

Answer 30

1. Aphaeresis 2. Autologous donation 3. Directed/designated donation

Question 31

Alternative Procedures to Allogeneic Blood Donation: Apheresis

Answer 31

Only the necessary components are collected. Rest is returned to donor.

Question 32

Alternative Procedures to Allogeneic Blood Donation: Autologous donation

Answer 32

Collection of blood from a person and its subsequent | re–infusion into the same person.

Question 33

Alternative Procedures to Allogeneic Blood Donation: Directed/Designated Donation

Answer 33

These are compatible blood donations made by | family and/or friends of a particular patient

Question 34

Transfusion: General Guidelines

Answer 34

Blood products are living human tissues – should actually be viewed as a blood “transplantation” not transfusion Only prescribe when benefit is likely to outweigh risk Prescribe according to accepted transfusion guidelines: www.sanbs.org.za Minimise blood loss Use non-blood fluids for resuscitation Transfuse to meet the clinical needs of a patient and not according to laboratory results Obtain informed consent

Question 35

General Indications for Red Cell Transfusion

Answer 35

Acute Blood Loss General Surgery Anaemia in Acute Coronary Syndromes(ACS) Anaemia Cardiac Surgery Obstetric Haemorrhage

Question 36

General Indications for Red Cell Transfusion: Acute Blood loss

Answer 36

An acute blood loss of ≥ 20% of blood volume (about 1000- 1200 ml of blood in an adult) will often result in the need for a red cell transfusion

Question 37

General Indications for Red Cell Transfusion: General Surgery

Answer 37

Consider transfusion if: • Pre-operative Hb is < 8 g/dl and the surgery is associated with major blood loss (> 500 ml) • Intra- or post-operative haemoglobin falls below 7 g/dl • Higher Hb may be indicated in patients at risk for myocardial ischaemia or who are > 60 yrs old • Pre-operative anaemia must be investigated in every case: medical management to raise Hb may be more appropriate than transfusion

Question 38

General Indications for Red Cell Transfusion: Anaemia in Acute Coronary Syndrome(ACS)

Answer 38

In patients with ACS there is evidence that a haemoglobin level below 8g/dl may be deleterious • T

Question 39

General Indications for Red Cell Transfusion: Anaemia

Answer 39

he aetiology of anaemia should be investigated and, as far as possible, a definitive diagnosis should be made in every case • Medical management will be determined by cause • Appropriate alternatives to blood transfusion must be considered • Consider transfusion in normovolaemic patients only if they are severely symptomatic e.g. shortness of breath at rest, angina, incipient cardiac failure • Patients with Hb < 7g/dl often require a transfusion

Question 40

General Indications for Red Cell Transfusion: Obstetric Haemorrhage

Answer 40

During an obstetric haemorrhage, red cells should be administered to maintain the patient free of signs and symptoms of inadequate tissue oxygen delivery • Hb should be maintained between 6 and 10g/dl during the resuscitation phase

Question 41

Other Measures

Answer 41

1. Investigate all anaemias 2. Minimise surgical bleeding 3. Good antenatal care 4. Correct anaemia with conservative measures

Question 42

Minimise Surgical Bleeding

Answer 42

1. Pre-op - Early pre-operative evaluation for elective surgery -Address abnormal coagulation profiles, thrombocytopenia, liver/renal impairment -Stop/bridge anticoagulants prior to surgery (aspirin, clopidogrel, warfarin, NSAIDS) 1. Intra-Op -Cell saver technology: autotransfusion of recovered blood - Pre-operative autologous donations - Acute normovolaemic haemodilution - Haemostatic drugs - Local haemostatic agents (Thrombin glue, Microfibrillar collagen etc.) -Meticulous haemostasis, laparoscopic techniques etc. 3. Post-OpP -Cell saver technology: autotransfusion of recovered blood - Meticulous wound care and monitoring - Early intervention if bleeding

Question 43

Good Antenatal Care

Answer 43

Early booking Haematinics Early referral Family planning

Question 44

Correct Anaemia with Conservative Measures

Answer 44

Oral haematinics Erythropoietin Parenteral iron Address underlying condition!

Question 45

Transfusion Reactions: Types

Answer 45

1. Haemolytic Reactions 2. Allergic Reactions 3. Fluid Overload

Question 46

Transfusion Reactions: Haemolytic Reactions

Answer 46

Caused by patient Abs to transfused RBCs

Question 47

Transfusion Reactions: Allergic Reactions

Answer 47

Mainly caused by platelet & leukocyte remnants; cytokines NB. These can be removed by special filters in the blood

Question 48

Transfusion Reactions: Fluid Overload

Answer 48

To much product To quickly transfused

Question 49

Risk of Transfusion in SA

Answer 49

Higher risk for non-infectious than infectious complications after a blood transfusion • In South Africa: • SANBS 2014 Haemovigilance report: • Since the implementation of ID-NAT in 2005 (approximately 7,5 million donations screened), there has been only one case of HIV transmission via blood transfusion (2014) • 2014 haemovigilance report: – No Hep B, Hep C or malaria, but one case of HIV and one case of HTLV – Compare this to a total of 961 non-infectious complications in the same year SANBS. Haemovigilance report 2014. Just how dangerous is a transfusion? Carson JL et al. Red blood cell transfusion: A Clinical Practice Guideline From the AABB. Ann Intern Med. 26 March 2012

Question 50

Haemolytic Transfusion Reactions: Types

Answer 50

Ensue when transfused red cells are destroyed by the immune system Typically occurs when antigen-positive donor red cells are transfused to patient with clinically significant alloantibody to the corresponding antigen 1. Severe Acute HTRs (AHTRs) 2. Delayed HTRs (DHTRs)NP > 1,5

Question 51

Haemolytic Transfusion Reactions: Severe Acute HTR(AHTRs)

Answer 51

Occur within 24 hours of the incompatible transfusion Due to intravascular haemolysis caused by complement fixing IgM antibodies. (E.g. ABO A/bodies) Less severe AHTRs may also be caused by extravascular haemolysis due to IgG antibodies, (e.g. anti-D/anti-K) in recipients sensitized by previous transfusions or pregnancy

Question 52

Haemolytic Transfusion Reactions: Delayed HTRs (DHTRs):

Answer 52

Occur 5–8 days after transfusion Due to an anamnestic (secondary, IgG) immune response leading to extravascular haemolysis, in a previously sensitized recipient in whom no alloantibody can be detected in the pre-transfusion specimen Reported to be 1 in 2500 transfused units Amount of incompatible blood needed for HTR: – some people react after a few millilitres – others will tolerate a whole unit with minimal effects

Question 53

Haemolytic Transfusion Reactions: Clinical Presentation

Answer 53

Fever & chills: usually the 1st signs of an HTR – Not usually possible to distinguish from febrile non-HTR (FNHTR) – Due to release of anaphylatoxins • Back or loin pain: very common but cause is unknown • Sensations of unrest, dyspnoea: caused by lung perivascular and peribronchial oedema • Hypotension, shock: in 10% of patients with intravascular HTR but rarely seen in extravascular haemolysis – Complement activation probably a significant factor • Renal failure: may occur in either type of HTR but is more common in AHTR • DIC: seen in intravascular AHTRs but is very rare in extravascular HTRs HTR: INVESTIGATION

Question 54

Haemolytic Transfusion Reactions: Investigations

Answer 54

• STOP transfusion immediately! • Check all labelling: If wrong blood has been transfused, trace units of blood intended for that patient, so as to avoid incompatible transfusion to another patient • Obtain properly labelled specimen from patient and send to blood bank with the original transfusion bag and administration set • DAT,Peripheral blood film, Retic. count, Haptoglobin, LDH, Unconj. Bilirubin, etc. to confirm haemolysis • Blood bank: Repeat ABO and Rh testing, allo-antibody screening, crossmatches • If above tests fail to confirm an HTR, consider an alternative transfusion complication such as bacterial contamination

Question 55

Haemolytic Transfusion Reactions: Management

Answer 55

Guided by clinical picture: minimally symptomatic patients may be observed only, but severe reactions require early aggressive intervention • FIRST: Assess immediately for life threatening ABC compromise. Maintain venous access. Check patient identity. • ABO incompatibility and severe haemolysis: exchange transfusion may be needed • Prevent renal failure by maintaining urine output with IV fluids and diuretics. Consider vasopressor support. • Treat DIC • IVIG has been successfully used on occasion, as pretreatment when incompatible blood is given to an alloimmunised patient. • REPORT!

Question 56

Allergic Reactions: Types

Answer 56

Febrile Non-Haemolytic Transfusion Reaction Allergic Reaction Anaphylaxis

Question 57

Allergic Reactions: Febrile Non-Haemolytic Transfusion Reaction

Answer 57

Only a mild fever: Temp rises < 1.5°C, stable observations and patient is otherwise well. No resp. distress! Rx: paracetamol. Restart infusion at a slower rate,Observe closely

Question 58

Allergic Reactions: Allergic Reaction

Answer 58

Mild urticarial rash only. No resp. distress! Give chlorpheniramine 10 mg slowly IV. Restart transfusion at a slower rate. Observe more frequently.

Question 59

Allergic Reactions: Anaphylaxis

Answer 59

Resp Distress, Bronchospasm, angio-oedema,laryngeal oedema and stridor, abdominal pain, hypotension, etc Chlopheniramine 10 mg slow IV, O2 salbutamol nebulisation, adrenaline etc. Saline wash future components

Question 60

TRALI

Answer 60

• Transfusion Related Acute Lung Injury • Acute non-cardiogenic pulmonary oedema in the setting of transfusion • All blood products have been implicated, but more common in FFP, Platelets, Whole Blood, RBCs • Complex, partially understood pathogenesis: – Anti-granulocyte a/bodies or other bioactive substances in donor product, binding to or priming recipient granulocytes – Inflammation in pulmonary capillaries, granulocytes release proteolytic enzymes, O2 radicals – Pulmonary oedema ensues – TRALI

Question 61

TACO

Answer 61

Transfusion Associated Circulatory Overload Fluids given too fast or too much Inc JVP Inc CVP Inc Pulm Wedge Pressure BNP > 100pg/dl Post-transfusion BNP/Pre-transfusion BNP > 1,5