MLT GlobeDOH exam preparation (Abu Dhabi) – page 15
700 practice MCQs for the DOH medical laboratory exam. Level: Basic to intermediate.
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.
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.
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.
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.
The blue laser used in most clinical flow cytometers to excite FITC and PE emits light at about:
A 488 nm blue laser excites FITC and PE and is standard in clinical instruments. A 633–640 nm red laser is used for dyes such as APC.
Children with sickle cell anemia are given penicillin prophylaxis mainly because functional asplenia greatly raises the risk of sepsis from:
Repeated splenic infarction causes loss of splenic function, and the spleen is key for clearing encapsulated bacteria such as S. pneumoniae. The other organisms are not linked specifically to asplenia.
Both parents have beta-thalassemia trait. What is the chance that each pregnancy will result in a child with beta-thalassemia major?
Beta-thalassemia is autosomal recessive. Two carriers have a 1 in 4 chance of an affected child, 1 in 2 of a carrier and 1 in 4 of an unaffected non-carrier child.
The normal life span of platelets in the circulation is about:
Platelets survive about 7–10 days and are then removed mainly by the spleen and liver. 120 days is the red cell life span.
If dietary intake stops completely, body stores usually last about:
The liver holds several milligrams of B12, enough for years, whereas folate stores last only a few months. So folate deficiency develops much faster than dietary B12 deficiency.
Helmet cells and triangular red cells with sharp angles seen in a patient with DIC are classified as:
Helmet cells and triangular forms are types of red cell fragments (schistocytes), formed when cells are cut by fibrin strands or damaged surfaces. Acanthocytes are whole cells with irregular spicules.
A man with known CLL for 8 years develops fever, weight loss, a rapidly growing lymph node and very high LDH. The most likely event is:
Richter transformation is the change of CLL into an aggressive lymphoma, usually DLBCL, with B symptoms, rapidly enlarging nodes and high LDH. The other disorders are not typical outcomes of CLL.
A dehydrated patient has hematocrit 0.55 L/L, normal red cell mass, normal EPO and no mutation. The best term is:
Loss of plasma volume raises the hematocrit without increasing red cell mass; correcting dehydration normalizes it. Secondary polycythemia has a true rise in red cell mass with high EPO.
Flow cytometry shows CD19+ B cells with kappa:lambda ratio of 12:1. This most suggests:
Normal B cells show a kappa:lambda ratio of about 1–2:1 (roughly 0.5–3); a strongly skewed ratio indicates light chain restriction and clonality. T-cell clonality is not assessed by light chains.
An analyzer flags 'blasts?' on a sample with a normal-looking scatter plot. According to good practice, the technologist should:
Suspect flags have limited specificity, so a smear review confirms or excludes abnormal cells. Rerunning or diluting does not answer the morphologic question.
A patient starting clozapine is followed with regular absolute neutrophil counts because this drug can cause:
Clozapine can cause sudden, severe neutropenia (agranulocytosis), so ANC monitoring is required. It is a classic example of drug-induced neutropenia.
A healthy woman's blood smear shows about 1–2% eosinophils and less than 1% basophils. These values are:
Normal adult differentials include about 1–5% eosinophils and 0–1% basophils. No abnormality is present.