ABO groups and discrepencies Flashcards
Forward grouping is defined as:
detecting antigens on an individuals red cells via reagent antisera
What percentage of the white population has type O blood?
45%
Why is reverse grouping not performed on cord blood specimens?
Antibodies are generally not present at birth
Which of the following is unique to the ABO system when compared with other blood group systems?
Individuals have antibodies to antigens they lack without foreign stimulus
How are ABH antigens formed?
production of specific glycosyltransferases add sugars to precursor substances
What immunodominant sugar is responsible for H specificity?
L-fucose
What does the hh genotype refer to?
Bombay
What is the biochemical structure of secreted A, B, and H substances?
Glycoprotein
What substances are found in a group A secretor?
A, H
What is a “lectin”?
Seed extracts that agglutinate human cells with moderate specificity
What percentage of the blood Type A white population is type A2?
20%
What is the source of anti-H lectin?
Ulex Europaeus
What is the most important use for anti-B lectin?
Differentiating a true B from an acquired B
All of the following are technical errors that could result in ABO discrepancies except:
Failure to warm reagents
A patient was previously typed as blood group O. Forward grouping was negative with anti-A and anti-B. Reverse grouping showed reactivity with A1 cells and B cells. The technologist reported this patient’s type as A. What technical error occurred?
Clerical error
An elderly patient is documented as being type O. The forward grouping is negative with anti-A and anti-B. The reverse grouping showed no reactivity with A1 cells and B cells. What can be done to correct the discrepancy?
Incubate the patient serum and reagent cells for 15 minutes at room temp.
What testing is available that will differentiate between a true B and an acquired “B”?
Secretor studies
Anti-B lectin
Acidification of anti-B reagent
Reverse grouping was performed on an AB person. The technologist observed a very weak agglutination macroscopically. The cells appeared as “stacked coins” under a microscope. Which reagent should be added to the tube and recentrifuged in an attempt to resolve the discrepancy?
Saline
