ABO Discrepancies Flashcards
Forward type and reverse type not matching is known as what?
ABO discrepancy
TRUE or FALSE:
ABORh testing is considered routine testing
TRUE
Why is a reverse type not done on babies under 6 months old?
They have not formed antibodies yet
TRUE or FALSE:
If forward and reverse types disagree, repeat BOTH
TRUE
What are the 3 most common causes of ABO discrepancies?
-Reagents
-Wrong sample
-Testing errors
TRUE or FALSE:
Clerical error is the #1 error in blood bank
TRUE
Excess antibody
Prozone
Excess antigen
Postzone
Reasons reagents can cause a discrepancy (3)
-Wrong one used
-Expired or contaminated
-Omitted in testing
Using the wrong concentration of cells can cause what result?
False negative
Prozone and Postzone will give what result?
False negative
Reasons wrong sample can cause a discrepancy (2)
-Wong patient sample used (patient not properly identified/sample mix up in lab)
-Specimen not handled or stored properly (left on tray for several hours or left at room temp for several days)
Testing errors that can cause ABO discrepancy (7)
-Wrong temperature
-Wrong centrifugation
-Misinterpretation of a weak reaction or mixed field agglutination (mfa) as negative (overshaking)
-Failure to interpret hemolysis as a positive reaction
-Clerical errors in recording
-Tubes labeled incorrectly
-Over-reading - not shaking buttons off tube bottom
Why is hemolysis considered a positive reaction in blood bank?
Complement activation
Definition:
2 cell populations present
Mixed field agglutination
Types of discrepancies (4)
-Forward discrepancy due to additional reactions or antigens
-Forward discrepancy due to missing antigens
-Reverse due to additional reactants or antibodies
-Reverse due to missing antibodies
An inherited phenomenon primarily due to a genetic mutation that causes the sialic acid on RBC membranes to not be present and exposes a different antigen on the cell membrane (Tn antigen site).
-Occurs regardless of blood type
-will agglutinate everything
Polyagglutination
Wharton’s jelly or rouleaux can cause this
Non-specific agglutination
To avoid non-specific agglutination you should wash cells how many times?
4-8
Name the ABO discrepancy:
-Usually occurs in type A1 patients
-Is due to intestinal obstruction or cancer
Acquired B
Name the ABO discrepancy:
-Bacterial enzyme cleaves off the active group of A making it look like a B antigen and could react with B antisera
Acquired B
TRUE or FALSE:
The protein in typing reagents can reduce the zeta potential enough to cause false reactions in sensitized red cells
TRUE
Rare phenomenon between fraternal twins
Chimera-mixture of blood
Name the ABO discrepancy
B (A) Phenotype
Ways to resolve B (A) phenotype? (2)
-Test with additional monoclonal anti-A reagent by a different manufacturer
-Use polyclonal human anti-A reagent
Name the ABO discrepancy
Acquired B Phenotype
Name the ABO discrepancy:
-The B gene transfers trace amounts of N-acetylgalactosamine and D-galactose to the H antigen acceptor molecule
-Increased sensitivity of reagent anti-sera causes the weak forward reaction with Anti-A
B(A) phenotype
Name the ABO discrepancy:
-Found in patients that have diseases of lower GI tract, cancers of colon, intestinal blockage, or infection with Gram Negative
Acquired B phenotype
The following resolves what ABO discrepancy:
-Test the patient’s serum/plasma against autologous red blood cells
-Test patient red cells with additional monoclonal anti-B reagents from another manufacturer that are documented not to react with the antigens associated with this discrepancy
-Secretor studies (this ABO discrepancy will only have A substance in secretions)
Acquired B phenotype
Name the ABO discrepancy:
Subgroup of A
The following are resolutions for which ABO discrepancy:
-Repeat red cell testing with extended incubation times
-Include human polyclonal anti-A,B or monoclonal blend anti-A,B
Subgroup of a
If a subgroup of A is suspected, what must be tested? (2)
A1 Lectin and A2 cells
What plant does the A1 Lectin come from?
Dolichos biflorus
A1 Lectin is ran in what part of ABO testing?
Front typing
A2 cells will only agglutinate with which blood group types?
Group O and B
Which subgroup of A is associated with a 2+ mixed-field agglutination reaction?
A3
Name the ABO discrepancy: (Additional reactions/antibodies)
Rouleaux
Rouleaux can be observed in which 2 diseases/disorders?
-Multiple Myeloma
-Waldenstrom’s Macroglobulinemia
Name the ABO discrepancy: (additional reactions/antibodies)
Cold alloantibody
The following would resolve which ABO discrepancy:
-Test the patient’s serum with screening cells and auto control at room temperature
Auto or Allo antibody
Allo or Auto antibody
Cold auto antibody
Allo or Auto antibody
Cold allo antibody
When patient’s serum is tested with his/her own red cells to determine whether an autoantibody is present
Autologous control
aka
Auto Control
If you have positive reactions with A1, B, and screening cells - and the auto control is positive - what are you liking dealing with?
Cold autoantibody
Most common discrepancy in a healthy individual?
Subgroups with Anti-A1
Most frequent cause of weak or missing antibody (3)
-Babies
-Elderly
-Immunocompromised
Optimum temperature for Anti-A and Anti-B
4C
Name the ABO discrepancy:
Missing or Weak antibodies in serum testing
The following will resolve which ABO discrepancy:
-Determine patient’s age and immunoglobulin level
-Incubate serum testing for 15 minutes at room temperature, centrifuge, and examine
-If room temperature incubation is still negative, place serum testing at 4C for 5 minutes with an autologous control
Missing or Weak antibodies in serum testing
Interpret the following:
Cold autoantibody
Interpret the following:
Group O
Interpret the ABO result:
Normal A1
Interpret the ABO result:
Normal A2
Interpret the ABO result:
Normal B
Interpret the ABO result:
Normal O
Interpret the ABO result:
Normal A1B
Interpret the ABO result:
Normal A2B
Interpret the ABO result:
A2B with Anti-A1
Interpret the ABO result:
A2 with Anti-A1
Interpret the ABO result:
B with missing anti-A
Interpret the ABO result:
A with acquired B antigen
Interpret the ABO result:
O with rouleaux
Interpret the ABO result:
Group B with cold autoantibody (Anti-I)
Interpret the ABO result:
Group O infant
Interpret the ABO result:
Bombay type
Interpret the ABO result:
A with cold alloantibody
Most common autoantibody
Anti-I
