2. INTRODUCTION
• The purpose of pre-transfusion testing is to
select blood and its component that;
• 1. Will have acceptable survival when
transfused.
• 2.Will not cause destruction of recipient’s red
cells.
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3. Definition
• The term compatibility testing or Pre-
Transfusion testing refers to a set of
procedures required before blood is issued as
being compatible.
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4. Compatibility testing procedure
involves
• 1.Proper identification of recipients (Patients )
blood sample.
• 2.Checking the patients previous records
• 3.ABO and Rh grouping of recipient
• 4.Screening for irregular antibodies with
identification
• 5.Selection of ABO & Rh compatible donor,
free from blood transmissible infection &
irregular antibodies
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8. 2.Checking the patients previous
records
• If the patient has history of transfusion,
his/her previous records must be checked for
…
• 1.ABO & Rh blood group
• 2.Presence of unexpected antibodies
• 3.Any problems in compatibility testing
• 4.Any transfusion reactions
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11. 3. ABO & Rh grouping
• ABO & Rh grouping of patients sample must
be performed by using recommended
techniques.
• Weak D testing is not recommended as
provision of Rh (D) negative blood to these
patients will not result in any harm, even if
they test positive for weak D
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12. 4. Screening & identification of
irregular antibodies
• The main purpose of screening for irregular
antibodies before doing cross-match is to
select compatible blood before hand in those
patients who have formed antibodies
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16. • The term compatibility test and cross-
matching are sometimes used
interchangeably.
• However, they should be clearly differentiated
• A cross –match is only a part of a compatibility
test.
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17. • Cross match test is carried out to ensure that
there are no antibodies present in patients
serum that will react with donor cells when
transfused.
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18. The two main functions of cross
match test are
• 1. It is final check of ABO compatibility
between the donor and patient
• 2. it may detect the presence of an antibody in
the patient’s serum which will react with an
antigen on donor red cells which was not
detected in antibody screening because of the
absence of corresponding antigen in the
screening cells
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19. • Historically cross match testing procedures
had been divided into two parts…..
• 1.Major cross match
• 2.Minor cross
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21. AIM
• To perform the Minor cross match by using
saline suspension method in the given blood
sample.
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22. PRINCIPLE
• Minor crossmatch is done to detect any
serological incompatibility b/w patient cells
and donor serum.
• Minor cross match is done with a saline
suspension of patients cells and donor serum
to look for any complete reactive antibodies
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24. Procedure
• 1.label the tube as minor crossmatch with
donor number
• 2.Using a Pasteur pipette add 1 drops of 5 %
patient red cell suspension to the labelled
tube
• 3.using another Pasteur pipette add 2 drops
of donor’s serum to the same tube
• 4. Mix the tube well and centrifuge at 1000
RPM for 1 min
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25. • 5.Gently dislodge the cell button and observe
for agglutination or hemolysis
• 6.If there is agglutination or hemolysis , it
indicates minor incompatibility
• Compatible : NO agglutination or hemolysis
• Incompatible : Agglutination or hemolysis
seen
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27. Purpose of Major cross match
• Screening of any serological incompatibility
b/w donor’s red blood cells and patient’s
serum
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28. Principle of major cross match
Major cross match is done to detect any
serological incompatibility b/w donor’s cells
and patients serum.
Major crossmatch is verified with a coombs
reaction to detect even the incomplete
antibodies.
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29. Major cross match Techniques
• 1. Immediate spin method
• 2.saline room temperature technique
• 3.Albumin addition technique
• 4.Antiglobulin technique
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30. Requirements
• Materials :
• 1. 75 X 12 mm test tubes
• 2.Test serum
• 3.Reagent “o” Positive cells
• 4.Antiglobulin reagent (AHG)
• 5.Positive control ( IgG coated red cells)
• 6.22 % Bovine Albumin
• 7.Microscope
• 8.Glass slides
• 9.Pasteur pipette
• 10.Centrifuge
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31. Immediate spin technique/Saline
room temperature technique
• Immediate spin technique or saline room
temperature technique is enough to rule out
any ABO grouping error
• but are inadequate for identification of
clinically significant IgG type of antibodies.
• Thus both these techniques are not good,
• Especially if antibody screening has not been
carried out earlier.
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32. Indirect Anti globulin Technique
• IAT test is widely used in cross matching as it
detects majority of incomplete antibodies.
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33. Factors Affecting IAT
• 1.Temperature ( 37 oc)
• 2.Serum : Cell ratio
• 3.Incubation time
• 4. Suspending Medium
( sensitivity of IAT increased with addition of
22 % bovine albumin , enzyme or LISS)
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34. Albumin addition Technique
• This technique is also capable of detecting
reactive at 37oc but is not as sensitive as IAT
technique.
• It may be incorporated as an alternative
technique to IAT at some places
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35. Major cross match procedure
• 1.put two drops of patients serum in
prelabelled test tube
• 2.Add one drop of 2 – 4% suspension of donor
red cells
• 3.Mix the contents and incubate for 5-10 min
for immediate spin method or 40-50 min for
saline room temperature technique
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36. • 4.Centrifuge the tubes at 1000 RPM for one
min.
• 5.In case of saline room temperature
technique , centrifugation is optional
• 6.Examine the tubes or haemolysis or
agglutination
• 7.If haemolysis or agglutination is present at
this stage , the cross- match is incompatible.
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37. • 8.if –ve no hemolysis or agglutination, wash
the cells three to four times with saline and
decant the last wash completely .
• 9.Add one drop of AHG reagent
• 10. Centrifuge the tubes 1000 RPM for 1 min.
• 11.Look for agglutination or hemolysis with
optical aid.
• 12.Record the results
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38. • 13.If the test is negative add one drop control
IgG coated red cells . Centrifuge again at 1000
rpm for 1 min
• 14.look for hemolysis or agglutination
• 15 if no agglutination or hemolysis , the test is
invalid repeat the procedure
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39. Interpretation
• Haemolysis or agglutination at any stage of
the test procedure except after adding control
IgG coated red cells indicates incompatible
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40. Causes of +ve Results in X- match
• 1.Incompatible immediate spin crossmatch with
negative antibody screen.
• Eg; Incorrect ABO grouping of Pt. & Donor
• Weak expression of Ag which do not detected on
routine serological testing
• 2.Positive antibody screen with incompatible
AHG crossmatch
• 3.Donor red cells with a positive DAT
• 4.Problems in pt. serum Eg; Multiple myeloma
• 5.Dirty glass ware
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