ABO groups and discrepencies

Question 1

Forward grouping is defined as:

Answer 1

detecting antigens on an individuals red cells via reagent antisera

Question 2

What percentage of the white population has type O blood?

Answer 2

45%

Question 3

Why is reverse grouping not performed on cord blood specimens?

Answer 3

Antibodies are generally not present at birth

Question 4

Which of the following is unique to the ABO system when compared with other blood group systems?

Answer 4

Individuals have antibodies to antigens they lack without foreign stimulus

Question 5

How are ABH antigens formed?

Answer 5

production of specific glycosyltransferases add sugars to precursor substances

Question 6

What immunodominant sugar is responsible for H specificity?

Answer 6

L-fucose

Question 7

What does the hh genotype refer to?

Answer 7

Bombay

Question 8

What is the biochemical structure of secreted A, B, and H substances?

Answer 8

Glycoprotein

Question 9

What substances are found in a group A secretor?

Answer 9

A, H

Question 10

What is a “lectin”?

Answer 10

Seed extracts that agglutinate human cells with moderate specificity

Question 11

What percentage of the blood Type A white population is type A2?

Answer 11

20%

Question 12

What is the source of anti-H lectin?

Answer 12

Ulex Europaeus

Question 13

What is the most important use for anti-B lectin?

Answer 13

Differentiating a true B from an acquired B

Question 14

All of the following are technical errors that could result in ABO discrepancies except:

Answer 14

Failure to warm reagents

Question 15

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?

Answer 15

Clerical error

Question 16

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?

Answer 16

Incubate the patient serum and reagent cells for 15 minutes at room temp.

Question 17

What testing is available that will differentiate between a true B and an acquired “B”?

Answer 17

Secretor studies
Anti-B lectin
Acidification of anti-B reagent

Question 18

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?

Answer 18

Saline