Hello

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Hello
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ABO Discrepancies
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A Blood Group

• A1
• A2
• A3
• A int
• A m
• A x
• A lae
• A fint
• A bantu
• A el
• A end

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B Blood Group

• B 3
• B m
• B x
• B el

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Anti A1

• A2
• A2B
• A3
• Ax
• Oh

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Anti H

• A1
• A1B
• Oh
• Ah
• Bh

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Lectin

• Dolichos biflorus
• Ulex eurapeus
• Lotous tetragonolobus

Microbes

• Small-pox
• E.coli
• Y.pestis
• Pneumonia

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Non Reactive Agglutination

• Rouleaux formation
• Cold Antibody
• Wharton jelly

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Acquired B cell

• Limited mainly to Group A1 individuals with
• Lower GI tract disease
• Cancer of colon/rectum
• Intestinal obstruction
• Gram negative septicemia (i.e. E. coli)

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Acquired B

• Bacteria (E. coli) have a deacetylating enzyme
  that effects the A sugar.

Acquired B Phenotype
Group A individual
N-acetyl galactosamine
Galactosamine now resembles D-galactose (found
in Group B)
Bacterial enzyme removes acetyl group
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Cis AB
A
B
A
B
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Secretary Substance

• Stomach carcinoma
• Pancreatic carcinoma
• Ovarian carcinoma

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B(A) phenotype

• Similar to acquired B
• Patient is Group B with an apparent extra A
  antigen
• The B gene transfers small amounts of the A sugar
  to the H antigen
• Sometimes certain anti-A reagents will detect
  these trace amount of A antigen
• Resolution test with another anti-A reagent
  from another manufacturer

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False Negative Results in ABO Testing

• Reagent or test serum not added to a tube
• Hemolysis not identified as a positive reaction
• Inappropriate ratio of serum ( or reagent ) to
  red cells
• Tests not centrifuged sufficiently
• Tests incubated at temperatures above 20-24 C
• Incorrect interpretation or recording of test
  results

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False Positive Results in ABO Testing

• Over centrifugation of tubes
• Use of contaminated reagents, red cells, or
  saline
• Use of dirty glassware
• Incorrect interpretation or recording of test
  results

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Lets practice !
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Case study 1
Initial hypothesis Forward Group O Rh
Positive Reverse Group B ABO discrepancy is an
unexpected antibody reaction with AI cells.
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Resolution All tubes are reverified for positive
identification. No errors are found. A new sample
is requested to investigate the potential of a
mislabeled sample. All testing is repeated. The
results are the same. History She was
crossmatched 5 years ago and was typed as B
positive. She was the recipient of a bone
marrowtransplant due to aplastic anemia. The
donor was a group 0, D-positive sibling.
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Case study 2
Initial hypothesis Forward Group A Rh
Positive Reverse Group AB ABO discrepancy is a
missing antibody.
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Resolution All tubes are reverified for positive
identification. No errors are found. A new sample
is requested to investigate the potential of a
mislabeled sample. All testing is repeated. The
results are the same. History Patient is 95
years old and has decreased production of anti-B
due to her age. To prove this theory, room
temperature incubation at 4? C for 10 minutes is
performed testing the patient's serum against A1
and B cells, an auto control, and
antibody screening cells. The negative auto
control indicates that no autoantibody is present
at room temperature, or 4? C. The negative
screening cells indicate that no cold-reactive
alloantibody is present in the sample. The
patient's ABO type is group A.
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Case study 3
Initial hypothesis Forward Group AB Rh
Positive Reverse Group AB No ABO discrepancy
Because the manufacturer's insert requires the
performance of a direct antiglobulin test (DAT)
whenever the AB typing is determined, a DAT is
performed.
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ABO Discrepancies
Anti-A Anti-B Anti-AB A1Cell B Cell
4 0 4 2 4
Subgroup of A
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ABO Discrepancies
Anti-A Anti-B Anti-AB A1Cell B Cell O Cell Auto
Polyclonal antiserum 1 1 1 4 4 0 0
Monoclonal antiserum 0 0 0
Polyagglutination
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Example 1
Anti-A Anti-B A1 Cells B Cells
3 0 0 1
Problem Causes Resolution
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Example 2
Anti-A Anti-B A1 Cells B Cells
3 1 0 4
Problem Causes Resolution
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Example 3
Anti-A Anti-B A1 Cells B Cells
2 0 1 4
Problem Causes Resolution
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Example 4
Anti-A Anti-B A1 Cells B Cells
0 2mf 3 0
Problem Causes Resolution
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Example 5
Anti-A Anti-B A1 Cells B Cells
0 0 0 0
Problem Causes Resolution
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Thank you