MLT GlobeASCP exam preparation (USA · MLS / MLT) – page 7
1200 practice MCQs for the ASCP medical laboratory exam. Level: Advanced.
For a patient with sickle cell disease starting chronic transfusion, many programs give units matched for which antigens to prevent alloimmunization?
Anti-C, anti-E and anti-K are the most frequent alloantibodies in these patients, so prophylactic matching lowers alloimmunization.
Many laboratories omit the immediate-spin and room-temperature phases in the antibody screen mainly because:
Cold-reactive IgM antibodies such as anti-M, anti-P1 and anti-Lea are found in these phases and are rarely significant.
Apheresis platelets stored at 20–24 °C with agitation, and with no additional bacterial risk-control step, expire after:
Conventional room-temperature platelets have a 5-day shelf life because of the risk of bacterial growth. Seven-day dating is allowed only when an extra bacterial risk-control strategy is used.
Four-factor prothrombin complex concentrate, used for urgent warfarin reversal, contains factors:
Four-factor PCC contains the vitamin K–dependent factors II, VII, IX and X (plus proteins C and S). These are the factors reduced by warfarin.
The minor crossmatch, no longer routinely performed, tests:
The minor crossmatch detects donor antibodies against the patient's red cells. It was dropped because donor plasma is screened for unexpected antibodies.
What is the main purpose of the ISBT 128 labeling system?
ISBT 128 gives each donation a globally unique identification number and standard codes for product type, ABO/D and expiry. This supports traceability from donor to recipient.
Why is the collection bag gently mixed throughout whole blood donation?
Continuous mixing distributes the anticoagulant evenly so small clots do not form. Clots make the unit unusable and can block filters.
During donation, a swelling appears at the needle site. What is the correct action?
A hematoma means blood is leaking into tissues. The collection is stopped, the needle removed, and firm pressure with a cold pack applied.
Why do Lewis antibodies not cause HDFN?
Lewis antibodies are usually IgM, which cannot cross the placenta, and fetal and newborn red cells express little Lewis antigen.
At the first prenatal visit, which blood bank tests are routinely performed on every pregnant woman?
All pregnant women should have ABO, D and an antibody screen early in pregnancy to detect clinically significant antibodies and identify RhIG candidates.
Diego antigens are carried on:
Diego antigens, including Dia/Dib and Wra/Wrb, are on band 3. Aquaporin-1 carries Colton antigens.
Anti-Vel is clinically important because it:
Vel is a high-prevalence antigen; anti-Vel is often IgM and IgG, binds complement and can cause severe intravascular hemolysis.
Which group of antibodies is usually IgM, reacts best at room temperature or below, and is rarely clinically significant?
Lewis, P1 and M antibodies are usually cold-reactive IgM. Kell, Duffy, Kidd, Rh and S/s/U antibodies are usually IgG and significant.
Compared with ABO antigens, Rh antigens on fetal and newborn red cells are:
Rh antigens are well expressed early in fetal life, which is why Rh antibodies can cause severe fetal disease. ABO antigens are weaker at birth.
Apart from anti-D, which Rh antibody most often causes severe hemolytic disease of the fetus and newborn?
Anti-c is the Rh antibody after anti-D most often linked to severe HDFN. Anti-C and anti-e usually cause mild disease.
A donor types D−, C−, c+, E−, e+. The genotype is:
No D, C or E is present, so both haplotypes must be dce. r′ would add C and r″ would add E.
Which acid is called "volatile" because the body removes it mainly through the lungs?
Carbonic acid is in equilibrium with CO2, which is exhaled. Non-volatile (fixed) acids such as sulfuric, lactic and keto acids must be buffered and excreted by the kidneys or metabolized.
Sucrose is a non-reducing disaccharide. Which two monosaccharides form it?
Sucrose is glucose linked to fructose through both anomeric carbons, so it has no free reducing group. Glucose + galactose is lactose; two glucose units form maltose.
What is the main action of glucagon on glucose metabolism?
Glucagon, released from pancreatic alpha cells during fasting, raises blood glucose by stimulating liver glycogen breakdown and glucose formation. The other actions are effects of insulin.
Mature red blood cells lack mitochondria. Their glycolysis therefore ends with the formation of:
Without mitochondria, pyruvate cannot enter the citric acid cycle, so red cells reduce it to lactate to regenerate NAD+. Acetyl-CoA formation needs mitochondrial pyruvate dehydrogenase.