Compatibility Testing for Blood Transfusion

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Compatibility Testing for Blood Transfusion

• RIH Department of Anesthesiology

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Blood Bank Issues
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ISBT International Society of Blood Transfusion
Recognizes the Presence of Multiple Antigens on
the Surfaces of Red Blood Cells that define Blood
Group Systems
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BLOOD GROUP SYSTEMS
ANTIGENS 
  ISBT NUMBER 
  ISBT SYMBOL 
CONVENTIONAL NAME 


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BLOOD GROUP SYSTEMS
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Population Distribution of Major Blood Groups
O Rh pos 38 O Rh neg 7 A Rh
pos 34 A Rh neg 6 B Rh pos 9 B
Rh neg 2 AB Rh pos 3 AB Rh neg
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Why do we care?
Compatibility testing is done to avoid a
hemolytic transfusion reaction If the Host or
Recipient recognizes the donor RBC surface
antigens as foreign, the host will mount an
immune response to the donor RBCs
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Major Blood Groups
ABO
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ABO blood group antigens present on red blood
cells and IgM antibodies present in the serum
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Why do we have Anti-A or Anti-B
Antibodies??? They are not present in the
newborn They develop in the first years of
life Exposure to plant, bacterial, viral
antigens provokes this response
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Why do we have Anti-A or Anti-B
Antibodies??? Viruses transmitted from the
respiratory tracts of humans to other humans drag
along various antigens including ABO blood group
antigens. Prime the newborns immune
system. Reduces transmissibility of viruses
within a population.
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Major Blood Groups
Rhesus
47 Antigens make up the Rhesus Blood Group The
most significant is the D antigen
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There is no naturally occurring Anti D
Production of Anti D in the RH negative
recipient requires previous exposure to the D
antigen (in utero or by transfusion)
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If red cells are administered to an ABO- or
D-incompatible recipient, the recipient will
mount an antibody response to the foreign RBC
surface antigens
IgM is polyvalent and fixes complement
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Intravascular Clumping of Donor RBCs
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Intravascular hemolysis of donor RBCs
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Clumps and extruded RBC stroma result in organ
dysfunction and possible death Incidence
138,000 170,000 Mortality 130
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Other Blood Groups
No naturally occurring antibodies Immune response
requires previous exposure Weaker titers of
univalent antibodies
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Donor RBCs coated with host antibodies
Stiffer RBC membrane Susceptible to attack
by splenic macrophages
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But no intravascular clumping
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Bits of Donor RBC membrane lost traversing
splenic sinusoids (extravascular
hemolysis) Spherocytes Decreased RBC
survival Delayed anemia Priming for worse
reaction
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Donor
Questionnaire Medical history Lifestyle
Finger stick Checking Hct
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Donor
Needs a Hct of 0.38 A drop of donor blood is
placed into a test tube containing a CuSo4
solution
CuSo4 solution has a SG of 1.053 RBC with Hct gt
0.38 sink to the bottom of the test tube
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Donor
Side sample (20cc) collected for testing Blood
group and Infection The bag is
anticoagulated The unit is labeled with a
lot like any drug e.g. LH59321
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DIFFERENT LEVELS OF COMPATIBILITY TESTING
Landsteiner, 1899
Lifespan, 2008
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COMPATIBILITY TESTING
The purpose of pre-transfusion compatibility
testing is to PREVENT hemolytic transfusion
reaction Clerical and technical
components Samples must be labeled at the
bedside Two methods of ID required Name, SSN,
MR, DOB The phlebotomist must sign the tube
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COMPATIBILITY TESTING
Lab checks Identity Record of previous
specimen Record of previous ABO-Rh type History
of abnormalities
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COMPATIBILITY TESTING
Processing the specimen ABO Group determined
(forward and reverse) D typing determined Antibody
screen will be performed ABO/Rh identical or
compatible blood will be made available
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ABO TYPING
Front or forward type using monoclonal anti-A and
anti-B (commercial) The sample is diluted to Hct
0.08, the commercial antibodies added the test
tube is centrifuged The RBCs are then examined
for clumping (gross observation, gel suspension)
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Anti A
Anti B
Anti A
Anti B
A
B
Anti A
Anti B
Anti A
Anti B
O
AB
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ABO TYPING
Back or reverse type with A and B cells
Commercially available A and B cells are added to
two tubes of plasma AB B A O
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How do we know whether or not the host (or
recipient) has antibodies to minor blood group
antigens?
Add commercial RBCs with known important minor
antigens on their surface to host (or recipient)
plasma and centrifuge. Then incubate at body
temperature for 15-30 minutes Then add rabbit
antiglobulin
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If recipient antibodies have coated commercial
RBC surfaces
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Rabbit antiglobulin will bind to the Antibodies
and the RBCs will clump
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ANTIBODY SCREENING
Detection of unexpected clinically significant
antibodies against the minor blood group system
antigens Also called the indirect Coombs test or
the indirect antiglobulin test Positive in
between 0 - 8 of samples depending on the
population
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Possibly significant minor blood groups

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SCREENING TEST RESULTS

• A negative antibody screen allows blood to be
  dispensed using an immediate spin X-match or an
  electronic X-match, either of which confirms ABO
  compatibility
• A positive antibody screen requires a full
  antiglobulin phase X-match

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POSITIVE ANTIBODY SCREEN

• Can some or all of the antibodies be identified?
• Identify red cells which lack these antigen(s)

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Why does it take so much time?
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Why does it take so long?

• Sample collection
• Specimen transport
• Specimen centrifugation 15
• Testing 25

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How much ONeg Blood Is OK?
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How much ONeg?

• Past data from Vietnam war era
• Minimal auto antibodies in universal donor blood
• Per Dr. Sweeney gt 80 units before anti-A and
  anti-B cause problems

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What are our transfusion policies ?
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Policies

• Consent Covered in surgical consent
• Prescription Needs to be ordered
• Collection Label blood at bedside
• Name, MR , other
• Sign and date

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Policies

• Administration
• Inspect bag
• Verify ABO Rh
• Match IDs
• If no access to name bracelet use Innovian to
  match IDs
• 2 licensed personnel 2 signatures
• Normal saline only

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Whats new?

• 2007 Nature Biotechnology
• USA, Denmark, France, Sweden
• Convert blood types A, B, and AB
• to O, using bacterial glycosidase
• enzymes to cleave the antigens
• from the RBC surface.
• Need D negative cells

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The End
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Red blood cell compatibility table
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Plasma compatibility table
Donor
Recipient
AB
B
A
O
  
AB
  
  
A
  
  
B
  
  
  
  
O