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Blood Bank Purple Book
Terms in this set (39)
List several blood group antigens of low incidence.
These antigens are found in less than 1% of the population
List several high incidence blood group antigens
These antigens are found in 99% of the population
What 4 RBC antigens are not fully expressed at birth
What is sensitization?
Attachment of antibodies to antigen on a red cell
Why should serum separator tubes not be used for blood bank testing?
The gel can contaminate the red blood cells during sampling and can cause false-positive test results.
What is the terminal sugar on the B antigen?
What is the terminal sugar on the A antigen?
Which races have the higher percentage of group B?
Blacks and Chinese.
When might anti-A,B be used?
Anti-A,B is no longer used for routine typing but some labs use it for confirmatory typing of Group 0 red cell units.
What might cause the naturally-occurring isoagglutinins to be decreased in titer or missing?
Hypo- or agammaglobulinemia, leukemia, or the age of the patient.
Babies do not have detectable levels of naturally-occurring isoagglutinins in their plasma/serum until 3-6 months of age and titers decrease in the elderly.
What are lectins?
Extracts from plant seeds or animals that have antibody-like activity. For example, Dolichos biflorus agglutinates A1 cells and Ulex europeus reacts with the H determinant.
Why is anti-A1 not detected in an antibody screen?
Antibody screening cells are group 0. Anti-A1 only reacts with A1 cells.
How is anti-A1 usually discovered?
By an ABO discrepancy in which there is unexpected agglutination of Ai cells in the reverse grouping of a group A.
What group of blood should be transfused to a patient with anti-A1?
If the antibody is reactive at 37°C, cells lacking the A1 antigen (subgroup of A or group 0) should be transfused.
Anti-A1 that only reacts below 30°C is not considered clinically significant. In actual practice, some blood banks would provide subgroup of A or group 0 blood without testing the thermal range of the Anti-A1. The laboratory's
standard operating procedures (SOP) should be followed.
How can rouleaux interfere with blood bank tests?
Rouleaux cause false-positive reactions with all cells mixed witth the serum. Rouleaux are due to a serum protein abnormality and are usually seen in patients with multiple myeloma.
While retyping a group B trauma patient, the technologist observes mixed field agglutination with anti-B. Typing at the lime of admission showed 4+ agglutination with anti-B. What might have caused this change in
The patient might have been transfused with a large volume of group 0 ABCs. The transfusion history should be
How does the acquired B antigen usually react?
It typically agglutinates strongly with anti-A and weakly with anti-B, and the serum contains strong anti-B.
How might transfusion of non-group specific blood affect subsequent blood grouping result?
Donor cells are detectable in the recipient for up to 4 months, the life span of the RBC. Front grouping reactions may be weak or mixed-field if group 0 cells have been transfused to a patient of another group. Passive anti-A
and/or anti-B might be detected in the reverse grouping if large volumes of group 0 RBCs or platelets have been transfused to a patient of another group. These products contain some plasma and naturally-occurring isoagglutinins
How might agammaglobulinemia or leukemia affect a patient's blood grouping?
The naturally-occurring isoagglutinins might be weak or missing. With leukemia, certain antigens may also be
weak or missing.
Which blood groups are most likely to have anti-H?
Al and AIR (Bombays also have very string anti-H.)
What type of antibody is anti-H?
A naturally-occurring cold antibody
Which Rh antigen determines Rh type?
D (Rho). The presence of the D antigen denotes Rh-positive blood.
Why is an Rh control included when using high-protein Rh typing sera?
To detect false-positive reactions. If the Rh typing and the Rh control are both positive, the test is invalid.
Which Rh typing sera do not require use of an Rh control?
chemically modified anti-D,
or anti-D monoclonal/polyclonal blend.
These reagents have a low
protein content. Manufacturers frequently recommend the ABO front type as a suitable control. For group AB patients, a 6-8% albumin control or a saline control should be run. The manufacturer's instructions should always
How is testing for weak D performed and when is it required?
The Rh typing is carried through an indirect antiglobulin phase. Weak D testing is required on blood donors who
type Rh negative.
A unit of Rh-positive blood is erroneously typed as Rh negative. Will this mistake be caught in the
Not unless the Rh-negative recipient has anti-D and a complete crossmatch is performed.
A donor's RBCs fail to react with anti-D typing serum during routine testing. When the tubes are carried through the indirect antiglobulin phase, agglutination is observed with anti-D, but not with the control. How should this blood be classified for transfusion purposes?
The donor is a weak D, therefore, the unit is labeled Rh positive.
What Rh type should a weak D patient receive?
A weak D recipient may be transfused with either Rh positive or Rh negative.
Since the test for weak D is not routinely performed on recipients, Rh-negative blood is usually provided.
What are the consequences of infusing D positive RBCs into an Rh-negative recipient with a negative antibody screen?
There would not be a transfusion reaction, but the recipient might develop anti-D.
Which Rh gene complexes are most common in Caucasians?
RI, R2, and r. (The frequencies are 42%, 14%, and 26% respectively.)
Which Rh gene complex is common in Blacks and uncommon in Caucasians?
R°. (The frequency is 44% for Blacks and 4% for Caucasians.)
Which Rh gene complexes are present in only 2% or less of Caucasians
What is the most common genotype for Rh negatives?
What is the most common genotype for Rh positives?
What is the most common Rh antigen in Caucasians?
98% of Caucasians are positive for e.
What percentage of Rh-negative children would be expected from an R'R' mother and an R1r father?
None. All offspring would be Rh positive
A patient's RBCs react with anti-D, anti-C, anti-c, and anti-e. They do not react with anti-E. Which of the
following might be the patient's Rh genotype: R1r, RIR2, rr, r'r?
Which of the following Rh genotypes could develop anti-C: RIr, R'R', r'r, rr?
Which antibody could an RIRI individual make if exposed to R2R2 blood?
If a patient has anti-e, which of the following units could he receive: R2R2, R1R1, RIR2, R2R2, R1r?
R2R2 (DcE/DcE). All of the others have the e antigen.
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