Rh Blood Group System_Harr Flashcards
A complete Rh typing for antigens C, c, D, E, and
e revealed negative results for C, D, and E. How is
the individual designated?
A. Rh positive
B. Rh negative
C. Positive for c and e
D. Impossible to determine
Rh negative
Rh positive refers to the presence of D antigen; Rh
negative refers to the absence of the D antigen.
These designations are for D antigen only and do
not involve other Rh antigens.
How is an individual with genotype Dce/dce classified?
A. Rh positive
B. Rh negative
C. Rh null
D. Total Rh
Rh positive
This individual has the D antigen and is classified as
Rh positive. Any genotype containing the D antigen
will be considered Rh positive.
If a patient has a positive direct antiglobulin test,
should you perform a weak D test on the cells?
A. No, the cells are already coated with antibody
B. No, the cells are Rh null
C. Yes, the immunoglobulin will not interfere with
the test
D. Yes, Rh reagents are enhanced in protein media
No, the cells are already coated with antibody
If a person has a positive DAT, the red cells are
coated with immunoglobulin (anti-IgG and anti-C3d, or both). If a test for weak D were performed, the test would yield positive results independent of the presence or absence of the D antigen on the red cells.
Which donor unit is selected for a recipient with
anti-c?
A. r´r
B. R0R1
C. R2r´
D. r´ry
r´ry
The designation r´ is dCe and r y is dCE, neither of
which contains the c antigen. The other three Rh
types contain the c antigen and could not be used
in transfusion for a person with anti-c
Which genotype usually shows the strongest
reaction with anti-D?
A. DCE/DCE
B. Dce/dCe
C. D–/D–
D. -CE/-ce
D–/D–
The phenotype that results from D–/D– is classified
as enhanced D because it shows a stronger reaction
than expected with anti-D. Such cells have a greater
amount of D antigen than normal. This is thought to
result from a larger quantity of precursors being
available to the D genes because there is no
competition from other Rh genes
Why is testing for Rh antigens and antibodies different from ABO testing?
A. ABO reactions are primarily due to IgM antibodies and usually occur at room temperature; Rh antibodies are IgG and agglutination usually requires a 37°C incubation and enhancement media
B. ABO antigens are attached to receptors on the outside of the red cell and do not require any special enhancement for testing; Rh antigens are loosely attached to the red cell membrane and require enhancement for detection
C. Both ABO and Rh antigens and antibodies have
similar structures, but Rh antibodies are configured so that special techniques are needed to facilitate binding to Rh antigens
D. There is no difference in ABO and Rh testing; both may be conducted at room temperature with no special enhancement needed for reaction
ABO reactions are primarily due to IgM antibodies and usually occur at room temperature; Rh antibodies are IgG and agglutination usually requires a 37°C incubation and enhancement media
Detection of ABO and Rh antigens and antibodies
requires different reaction conditions. ABO antibodies are naturally occurring IgM molecules and react best at room temperature. Rh antibodies are generally immune IgG molecules that result from transfusion or pregnancy. Detection may require 37°C incubation and/or enhancement techniques.
Testing reveals a weak D that reacts 1+ after indirect antiglobulin testing (IAT). How is this result classified?
A. Rh-positive
B. Rh-negative, Du positive
C. Rh-negative
D. Rh-positive, Du positive
Rh-positive
Blood tested for weak D that shows 1+ reaction
after IAT is classified as Rh positive. The weak D
designation is not noted in the reporting of the
result
What is one possible genotype for a patient who
develops anti-C antibody?
A. R1r
B. R1R1
C. r´r
D. rr
rr
Only rr (dce/dce) does not contain C antigen. A person will form alloantibodies only to the antigens he or she lacks
A patient developed a combination of Rh antibodies: anti-C, anti-E, and anti-D. Can compatible blood be found for this patient?
A. It is almost impossible to find blood lacking the
C, E, and D antigens
B. rr blood could be used without causing a
problem
C. R0R0 may be used because it lacks all three
antigens
D. Although rare, ryr blood may be obtained from
close relatives of the patient
rr blood could be used without causing a
problem
The genotype rr (dce/dce) lacks D, C, and E antigens
and would be suitable for an individual who has
developed antibodies to all three antigens. This is the
most common Rh-negative genotype and is found in
nearly 14% of White blood donors.
A patient tests positive for weak D but also appears to have anti-D in his serum. What may be
the problem?
A. Mixup of samples or testing error
B. Most weak D individuals make anti-D
C. The problem could be due to a disease state
D. A D mosaic may make antibodies to missing
antigen parts
A D mosaic may make antibodies to missing
antigen parts
The D antigen is comprised of different parts
designated as a mosaic. If an individual lacks parts of
the antigen, he or she may make antibodies to the
missing parts if exposed to the whole D antigen.
Which offspring is not possible from a mother who
is R1R2 and a father who is R1r?
A. DcE/DcE
B. Dce/DCe
C. DcE/DCe
D. Dce/dce
DcE/DcE
DcE/DcE (R2R2) is not possible because R2 can be
inherited only from the mother and is not present in
the father.
Why is testing a pregnant woman for weak D not
required?
A. An Rh-negative fetus may yield false positive
results in a fetal maternal bleed
B. An Rh-positive fetus may yield false positive
results in a fetal maternal bleed
C. D antigen strength decreases during pregnancy
D. D antigen strength increases during pregnancy
An Rh-positive fetus may yield false positive
results in a fetal maternal bleed
If a weak D test is performed on a pregnant woman
with no previous history, a false-positive weak D test
may result from the presence of fetal blood if the
fetus is Rh positive. A pregnant woman with weak D
may be given Rh immune globulin without any
harmful consequences. Therefore, weak D testing
of pregnant women is not necessary.
What antibodies could an R1R1 make if exposed to
R2R2 blood?
A. Anti-e and anti-C
B. Anti-E and anti-c
C. Anti-E and anti-C
D. Anti-e and anti-c
Anti-E and anti-c
The R1R1 (DCe/DCe) individual does not have the E
or c antigen, and could make anti-E and anti-c
antibodies when exposed to R2R2 cells (DcE/DcE).
What does the genotype —/— represent in the
Rh system?
A. Rh negative
B. D mosaic
C. Rh null
D. Total Rh
Rh null
A person who is Rh null shows no Rh antigens on his
or her RBCs. Loss of Rh antigens is very unlikely to happen because Rh antigens are integral parts of
the RBC membrane. The Rhnull phenotype can result
from either genetic suppression of the Rh genes or
inheritance of amorphic genes at the Rh locus.
What techniques are necessary for weak D testing?
A. Saline + 22°C incubation
B. Albumin or LISS + 37°C incubation
C. Saline + 37°C incubation
D. 37°C incubation + IAT
37°C incubation + IAT
Weak D testing requires both 37°C incubation and
the IAT procedure. Anti-D is an IgG antibody, and
attachment of the D antigen is optimized at warmer
temperatures. Antihuman globulin in the IAT phase
facilitates lattice formation by binding to the
antigen–antibody complexes.
