MLS(ASCP)- | Ultimate Study Guide with Comprehensive
Questions, Correct Answer & Detailed Explanations – Latest
Update 2026/2027 | Already Graded A+
1. A patient’s CBC shows a hemoglobin of 8.2 g/dL, MCV of 68 fL, MCHC of
28 g/dL, increased RDW, decreased serum iron, increased TIBC, and
decreased ferritin. Which diagnosis is most likely?
A. β-thalassemia major
B. Iron deficiency anemia
C. Anemia of chronic disease
D. Sideroblastic anemia
Correct Answer: B. Iron deficiency anemia
Explanation:
The findings are classic for iron deficiency anemia, which is a microcytic,
hypochromic anemia. The low MCV and MCHC reflect impaired hemoglobin
production. A particularly important distinction is the iron profile: serum
iron and ferritin are decreased, while TIBC is increased because the body
increases its capacity to bind and transport the limited available iron. The
increased RDW reflects significant variation in RBC size, commonly seen as
iron deficiency progresses. In contrast, anemia of chronic disease usually has
decreased serum iron but normal or increased ferritin and decreased
TIBC.
2. A blood culture grows gram-positive cocci in clusters. The organism is
catalase positive and coagulase positive. Which organism is most likely
responsible?
A. Staphylococcus epidermidis
B. Staphylococcus aureus
C. Streptococcus pyogenes
D. Enterococcus faecalis
Correct Answer: B. Staphylococcus aureus
pg. 1
,Explanation:
Staphylococcus aureus is characterized by gram-positive cocci arranged in
clusters, a positive catalase reaction, and a positive coagulase test. Catalase
differentiates Staphylococcus species from Streptococcus species because
streptococci are catalase negative. Coagulase positivity strongly supports S.
aureus among the commonly encountered clinically significant staphylococci.
S. epidermidis is catalase positive but coagulase negative.
3. A patient's ABO typing demonstrates strong agglutination with anti-A
and anti-AB but no reaction with anti-B. The plasma reacts strongly with
B reagent cells. What is the patient's blood type?
A. A
B. B
C. AB
D. O
Correct Answer: A. A
Explanation:
The patient's red cells possess A antigen, demonstrated by reactions with
anti-A and anti-AB. The absence of reaction with anti-B indicates that B
antigen is absent. In reverse typing, the patient's plasma contains anti-B,
producing agglutination with B reagent cells. Group A individuals normally
have A antigen on their RBCs and anti-B in their plasma.
4. A peripheral smear demonstrates numerous target cells, microcytosis,
and hypochromia. The patient's RBC count is relatively high despite a
reduced MCV. Which condition should be suspected?
A. Iron deficiency anemia
B. β-thalassemia trait
C. Acute blood loss
D. Hereditary spherocytosis
Correct Answer: B. β-thalassemia trait
pg. 2
,Explanation:
Thalassemia trait commonly produces marked microcytosis with a relatively
preserved or increased RBC count. Target cells may also be prominent. This
helps distinguish thalassemia from iron deficiency anemia, where the RBC
count is often reduced and RDW is frequently increased. A patient with β-
thalassemia trait may have relatively mild anemia despite a strikingly low
MCV.
5. A urine specimen is positive for nitrite and leukocyte esterase.
Microscopy demonstrates numerous WBCs and bacteria. Which
interpretation is most appropriate?
A. The findings strongly support a bacterial urinary tract infection
B. The findings indicate glomerulonephritis
C. The findings are diagnostic of nephrotic syndrome
D. The findings indicate contamination by squamous cells
Correct Answer: A. The findings strongly support a bacterial urinary
tract infection
Explanation:
Nitrite positivity occurs when certain bacteria reduce urinary nitrate to
nitrite. Many gram-negative urinary pathogens, particularly Enterobacterales,
can produce this reaction. Leukocyte esterase indicates the presence of
WBCs because the reagent detects esterase activity from granulocytes. When
nitrite, leukocyte esterase, pyuria, and bacteriuria occur together, a bacterial
UTI is strongly supported.
6. A patient's PT is prolonged while the aPTT is within the reference
interval. Which coagulation pathway is primarily being evaluated by the
abnormal test?
A. Intrinsic pathway
B. Extrinsic pathway
C. Common pathway only
D. Fibrinolytic pathway
pg. 3
, Correct Answer: B. Extrinsic pathway
Explanation:
The PT primarily evaluates the extrinsic and common coagulation pathways.
Factor VII is the major factor assessed by the extrinsic pathway. The aPTT
evaluates the intrinsic and common pathways. Therefore, an isolated
prolonged PT can suggest a problem involving factor VII, early vitamin K
deficiency, warfarin therapy, or certain liver-related abnormalities affecting
factor production.
7. An acid-fast bacillus is recovered from a respiratory specimen. Which
staining method is most appropriate for demonstrating the organism?
A. Gram stain
B. Wright stain
C. Ziehl-Neelsen stain
D. India ink preparation
Correct Answer: C. Ziehl-Neelsen stain
Explanation:
Mycobacteria contain large amounts of mycolic acid in their cell walls,
making them resistant to decolorization by acid-alcohol after staining with
carbol fuchsin. This property produces the term acid-fast bacilli. The Ziehl-
Neelsen method is a classic acid-fast staining procedure. A modified acid-fast
procedure may also be used for certain organisms such as Nocardia and some
coccidian parasites.
8. A patient's serum sodium is 140 mmol/L, chloride is 104 mmol/L, and
bicarbonate is 12 mmol/L. What is the calculated anion gap?
A. 12 mmol/L
B. 18 mmol/L
C. 24 mmol/L
D. 36 mmol/L
Correct Answer: C. 24 mmol/L
pg. 4
Questions, Correct Answer & Detailed Explanations – Latest
Update 2026/2027 | Already Graded A+
1. A patient’s CBC shows a hemoglobin of 8.2 g/dL, MCV of 68 fL, MCHC of
28 g/dL, increased RDW, decreased serum iron, increased TIBC, and
decreased ferritin. Which diagnosis is most likely?
A. β-thalassemia major
B. Iron deficiency anemia
C. Anemia of chronic disease
D. Sideroblastic anemia
Correct Answer: B. Iron deficiency anemia
Explanation:
The findings are classic for iron deficiency anemia, which is a microcytic,
hypochromic anemia. The low MCV and MCHC reflect impaired hemoglobin
production. A particularly important distinction is the iron profile: serum
iron and ferritin are decreased, while TIBC is increased because the body
increases its capacity to bind and transport the limited available iron. The
increased RDW reflects significant variation in RBC size, commonly seen as
iron deficiency progresses. In contrast, anemia of chronic disease usually has
decreased serum iron but normal or increased ferritin and decreased
TIBC.
2. A blood culture grows gram-positive cocci in clusters. The organism is
catalase positive and coagulase positive. Which organism is most likely
responsible?
A. Staphylococcus epidermidis
B. Staphylococcus aureus
C. Streptococcus pyogenes
D. Enterococcus faecalis
Correct Answer: B. Staphylococcus aureus
pg. 1
,Explanation:
Staphylococcus aureus is characterized by gram-positive cocci arranged in
clusters, a positive catalase reaction, and a positive coagulase test. Catalase
differentiates Staphylococcus species from Streptococcus species because
streptococci are catalase negative. Coagulase positivity strongly supports S.
aureus among the commonly encountered clinically significant staphylococci.
S. epidermidis is catalase positive but coagulase negative.
3. A patient's ABO typing demonstrates strong agglutination with anti-A
and anti-AB but no reaction with anti-B. The plasma reacts strongly with
B reagent cells. What is the patient's blood type?
A. A
B. B
C. AB
D. O
Correct Answer: A. A
Explanation:
The patient's red cells possess A antigen, demonstrated by reactions with
anti-A and anti-AB. The absence of reaction with anti-B indicates that B
antigen is absent. In reverse typing, the patient's plasma contains anti-B,
producing agglutination with B reagent cells. Group A individuals normally
have A antigen on their RBCs and anti-B in their plasma.
4. A peripheral smear demonstrates numerous target cells, microcytosis,
and hypochromia. The patient's RBC count is relatively high despite a
reduced MCV. Which condition should be suspected?
A. Iron deficiency anemia
B. β-thalassemia trait
C. Acute blood loss
D. Hereditary spherocytosis
Correct Answer: B. β-thalassemia trait
pg. 2
,Explanation:
Thalassemia trait commonly produces marked microcytosis with a relatively
preserved or increased RBC count. Target cells may also be prominent. This
helps distinguish thalassemia from iron deficiency anemia, where the RBC
count is often reduced and RDW is frequently increased. A patient with β-
thalassemia trait may have relatively mild anemia despite a strikingly low
MCV.
5. A urine specimen is positive for nitrite and leukocyte esterase.
Microscopy demonstrates numerous WBCs and bacteria. Which
interpretation is most appropriate?
A. The findings strongly support a bacterial urinary tract infection
B. The findings indicate glomerulonephritis
C. The findings are diagnostic of nephrotic syndrome
D. The findings indicate contamination by squamous cells
Correct Answer: A. The findings strongly support a bacterial urinary
tract infection
Explanation:
Nitrite positivity occurs when certain bacteria reduce urinary nitrate to
nitrite. Many gram-negative urinary pathogens, particularly Enterobacterales,
can produce this reaction. Leukocyte esterase indicates the presence of
WBCs because the reagent detects esterase activity from granulocytes. When
nitrite, leukocyte esterase, pyuria, and bacteriuria occur together, a bacterial
UTI is strongly supported.
6. A patient's PT is prolonged while the aPTT is within the reference
interval. Which coagulation pathway is primarily being evaluated by the
abnormal test?
A. Intrinsic pathway
B. Extrinsic pathway
C. Common pathway only
D. Fibrinolytic pathway
pg. 3
, Correct Answer: B. Extrinsic pathway
Explanation:
The PT primarily evaluates the extrinsic and common coagulation pathways.
Factor VII is the major factor assessed by the extrinsic pathway. The aPTT
evaluates the intrinsic and common pathways. Therefore, an isolated
prolonged PT can suggest a problem involving factor VII, early vitamin K
deficiency, warfarin therapy, or certain liver-related abnormalities affecting
factor production.
7. An acid-fast bacillus is recovered from a respiratory specimen. Which
staining method is most appropriate for demonstrating the organism?
A. Gram stain
B. Wright stain
C. Ziehl-Neelsen stain
D. India ink preparation
Correct Answer: C. Ziehl-Neelsen stain
Explanation:
Mycobacteria contain large amounts of mycolic acid in their cell walls,
making them resistant to decolorization by acid-alcohol after staining with
carbol fuchsin. This property produces the term acid-fast bacilli. The Ziehl-
Neelsen method is a classic acid-fast staining procedure. A modified acid-fast
procedure may also be used for certain organisms such as Nocardia and some
coccidian parasites.
8. A patient's serum sodium is 140 mmol/L, chloride is 104 mmol/L, and
bicarbonate is 12 mmol/L. What is the calculated anion gap?
A. 12 mmol/L
B. 18 mmol/L
C. 24 mmol/L
D. 36 mmol/L
Correct Answer: C. 24 mmol/L
pg. 4
