MLT GlobeQCHP exam preparation (Qatar) – page 14
749 practice MCQs for the QCHP medical laboratory exam. Level: Intermediate.
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.
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.
A patient has anti-Fyb. To which blood group system does this antibody belong?
Fya and Fyb are Duffy antigens, so anti-Fyb is a Duffy antibody. Duffy antigens are destroyed by enzymes such as ficin.
Which group of antibodies is usually IgG, reacts at 37 °C/AHG and is clinically significant?
Kell, Duffy and Kidd antibodies are usually IgG and can cause hemolytic reactions and HDFN. The other groups are mostly cold-reacting IgM antibodies.
The chart listing which antigens are present on each reagent panel cell is called the:
The antigram (antigen profile sheet) lists the antigens on each panel cell. Reactions are compared with it to rule antibodies in or out.
An antibody made against a red cell antigen that the person lacks, after transfusion or pregnancy, is called:
Alloantibodies react with foreign antigens the person lacks. Autoantibodies react with the person's own red cells.
When the antibody screen is positive, the next step is usually to:
A positive screen shows an unexpected antibody. Its specificity is found by testing the plasma against a panel of typed red cells.
Red cell antibodies other than the expected anti-A and anti-B are called:
Antibody screening looks for unexpected antibodies, such as anti-D or anti-K, which are not normally present.
In a column (gel) agglutination test, a negative reaction appears as:
Unagglutinated cells pass through the gel during centrifugation and form a button at the bottom. Agglutinates are trapped at the top or within the gel.
A 'type and screen' request means the laboratory performs:
In a type and screen, the patient is grouped and screened. Units are crossmatched only if transfusion becomes likely, which saves blood inventory.
Once started, a unit of red cells should be completely transfused within:
Red cells should be infused within 4 hours of spiking the bag to limit bacterial growth at room temperature.
A group A, D-positive patient can receive red cells of which groups?
The patient's plasma has anti-B, so red cells must lack B (group A or O). Being D-positive, the patient can receive D-positive or D-negative cells.
According to WHO, the safest source of blood is:
WHO recommends collecting all blood from regular voluntary unpaid donors, who have the lowest rates of transfusion-transmissible infections.
Blood donated by a relative or friend for a specific named patient is called a:
A directed donation is intended for a named recipient. An autologous donation is the patient's own blood.
Transfusion-associated circulatory overload (TACO) is usually managed by:
TACO is fluid overload, so management is to stop the transfusion, sit the patient upright, give oxygen and give diuretics as needed.
Transfusion-associated graft-versus-host disease is caused by:
Viable donor T cells engraft and attack recipient tissues, including the marrow. Irradiating cellular components prevents it.
Kernicterus in a newborn with HDFN is caused by:
Very high unconjugated bilirubin is fat-soluble and can cross into the brain, causing permanent damage. Phototherapy and exchange transfusion aim to prevent it.
A D-negative pregnant woman without anti-D has an amniocentesis. What should she receive?
Amniocentesis can cause fetomaternal bleeding, so a non-sensitized D-negative woman should receive RhIG.
Most infants who need treatment for ABO HDFN are managed with:
ABO HDFN is usually mild, and phototherapy is enough in most cases. Exchange or intrauterine transfusion is rarely needed.