MLT GlobeBlood Banking: Rh system – page 2
79 Blood Banking MCQs on Rh system with answers and explanations.
The Rh blood group system was named after:
The name comes from rhesus monkeys. Antibodies raised against their red cells by Landsteiner and Wiener reacted with most human red cells.
A person is called 'Rh-positive' when their red cells carry which antigen?
In routine practice, Rh-positive means D-positive. The C, c, E and e antigens do not decide the Rh-positive or negative label.
The five principal antigens of the Rh system are:
The five main Rh antigens are D, C, c, E and e. D is the most immunogenic.
In Wiener notation, R2 corresponds to which Fisher-Race haplotype?
R2 = DcE. R1 = DCe, R0 = Dce and r = dce.
D-negative girls and women of childbearing age should receive D-negative red cells mainly to prevent:
D is highly immunogenic. Anti-D formed after transfusion could cause severe hemolytic disease in a future D-positive fetus.
Anti-D in a D-negative person usually arises after:
Anti-D is an immune antibody formed only after exposure to D-positive red cells, unlike naturally occurring anti-A and anti-B.
The older term 'Du' refers to what is now called:
'Du' was the old name for red cells with weakened D expression, now called weak D.
An RhD-negative person who has never been transfused or pregnant typically has which Rh antibody?
Unlike ABO antibodies, anti-D is not naturally occurring; it forms only after exposure to D-positive red cells through transfusion or pregnancy.
Which statement about 'incomplete' antibodies is FALSE?
Anti-A and anti-B are mostly IgM and agglutinate saline-suspended cells directly (complete). Incomplete antibodies are IgG, warm-reacting and AHG-dependent.
In most D-negative people of European descent, the D-negative phenotype is caused by:
Most D-negative Europeans are homozygous for deletion of RHD. An inactive RHD pseudogene (RHDψ) is a common cause in people of African descent.
Which Rh haplotype is much more common in people of African descent than in people of European descent?
R0 (Dce) is frequent in people of African ancestry but uncommon in Europeans, in whom R1 and r predominate.
Rh antibodies such as anti-D typically destroy red cells by which mechanism?
Rh antibodies are usually IgG and rarely activate complement. Coated cells are removed extravascularly, mainly in the spleen.
A D-positive patient makes an alloanti-D after transfusion of D-positive blood. The most likely explanation is that the patient has:
Partial D cells lack some D epitopes, so exposure to normal D can stimulate anti-D against the missing epitopes. Weak D type 1 has all epitopes, only fewer sites.
Serologic weak D phenotypes such as weak D types 1–3 are mainly caused by:
Weak D results from RHD variants that lower the number of D sites, usually from changes in transmembrane or intracellular parts of the protein. Missing epitopes define partial D.
A patient with a strongly positive DAT types D-positive with a high-protein anti-D reagent. What control is needed to validate this result?
High-protein reagents can agglutinate IgG-coated cells without true D. An Rh (diluent) control must be negative for the D result to be valid.
D-negative red cell stocks are low. Which patient is the most acceptable to receive D-positive red cells?
Anti-D mainly matters for future pregnancies. Switching an older male without anti-D to D-positive red cells is acceptable when supply is short.
A D-negative 30-year-old woman receives an apheresis platelet unit from a D-positive donor. What is recommended?
Platelet units contain small amounts of red cells that can sensitize to D. RhIG is recommended, especially for females of childbearing potential.
An anti-E reacts 3+ with R2R2 cells but only 1+ with R1R2 cells. This pattern is best explained by:
R2R2 cells are homozygous for E (double dose) and carry more antigen than heterozygous R1R2 cells. Most Rh antigens except D show dosage.
In ISBT numerical terminology, the D antigen is:
ISBT numbers are RH1 = D, RH2 = C, RH3 = E, RH4 = c and RH5 = e.
Cw is best described as:
Cw is a low-prevalence Rh antigen. Anti-Cw may be missed by screening cells and appear as an incompatible crossmatch.