MLS HEMATOLOGY EXAM /HEMATOLOGY MLS ACTUAL
EXAM 400 QUESTIONS AND CORRECT DETAILED
ANSWERS WITH RATIONALES (VERIFIED ANSWERS) |
ALREADY GRADED A+
Insufficient centrifugation will result in:
A. A false increase in hematocrit (Hct) value
B. A false decrease in Hct value
C. No effect on Hct value
D. All of these options, depending on the patient - ANSWER: A. Insufficient
centrifugation does not pack down the
red blood cells; therefore, the Hct, which is the
volume of packed cells, will increase.
Variation in red cell size observed on the peripheral smear is described as:
A. Anisocytosis
B. Hypochromia
C. Poikilocytosis
D. Pleocytosis - ANSWER: A. A mature erythrocyte is approximately 7-8 μm in
diameter. Variation in normal size is denoted by the
term anisocytosis. Hypochromia is a term that indicates increased central pallor in
erythrocytes, and poikilocytosis denotes variation in red cell shape.
Which of the following is the preferable site for bone marrow aspiration and biopsy
in an adult?
A. Iliac crest
B. Sternum
C. Tibia
D. Spinous processes of a vertebra - ANSWER: A. The iliac crest is the most
frequently used site for
bone marrow aspiration and biopsy. This site is the
safest and most easily accessible, with the bone just
beneath the skin, and neither blood vessels nor
nerves are in the vicinity.
Mean cell volume (MCV) is calculated using the following formula:
A. (Hgb / RBC) × 10
B. (Hct / RBC) × 10
C. (Hct / Hgb) × 100
D. (Hgb / RBC) × 100 - ANSWER: B. MCV is the average "volume" of the red cells. This
is
,obtained by dividing the Hct or packed cell volume
(PCV) by the red blood cell (RBC) count in millions per
microliter of blood and multiplying by 10. The MCV is
expressed in cubic microns (μm3) or femtoliters (fL).
What term describes the change in shape of erythrocytes seen on a Wright's-stained
peripheral blood smear?
A. Poikilocytosis
B. Anisocytosis
C. Hypochromia
D. Polychromasia - ANSWER: A. Variation in shape of the erythrocytes on a
peripheral
blood smear is poikilocytosis. Anisocytosis refers to a
change in size. Hypochromia is an increase in central
pallor in erythrocytes. Polychromasia describes the bluish tinge of the immature
erythrocytes (reticulocytes) circulating in the peripheral blood.
Calculate the mean cell hemoglobin concentration (MCHC) using the following
values:
Hgb: 15 g/dL (150 g/L)
Hct: 47 mL/dL (0.47)
RBC: 4.50 × 106/μL (4.50 × 1012/L)
A. 9.5% (.095)
B. 10.4% (.104)
C. 31.9% (.319)
D. 33.3% (.333) - ANSWER: C. MCHC is the average concentration of Hgb in red
cells expressed as a percentage. It expresses the ratio of the weight of Hgb to the
volume of erythrocytes and is calculated by dividing Hgb by the Hct, and then
multiplying by 100. A decreased MCHC indicates that cells are hypochromic. In this
example, (15 ÷ 47) × 100 = 31.9%. The reference range for MCHC is 32%-36%.
A manual white blood cell (WBC) count was performed. A total of 36 cells were
counted in all 9-mm^2 squares of a Neubauer-ruled hemacytometer. A 1:10 dilution
was used. What is the WBC count?
A. 0.4 × 10^9/L
B. 2.5 × 10^9/L
C. 4.0 × 10^9/L
D. 8.0 × 10^9/L - ANSWER: A. The formula used for calculating manual cell counts
using a hemacytometer is:
Number of cells counted × dilution factor × depth factor (10) divided by the area.
In this example, 36 × 10 × 10 = 3600 ÷ 9 = 400/mm^3 or 0.4 × 10^9/L.
,When an erythrocyte containing iron granules is stained with Prussian blue, the cell
is called a:
A. Spherocyte
B. Leptocyte
C. Schistocyte
D. Siderocyte - ANSWER: D. Siderocytes are red cells containing iron granules
and are visible when stained with Prussian blue.
A 7.0-mL ethylenediaminetetraacetic acid (EDTA) tube is received in the laboratory
containing only 2.0 mL of blood. If the laboratory is using manual techniques, which
of the following tests will most likely be erroneous?
A. RBC count
B. Hemoglobin (Hgb)
C. Hct
D. WBC count - ANSWER: C. Excessive anticoagulant causes shrinkage of cells;
thus, the Hct will be affected. RBC and WBC counts
remain the same, as does the Hgb content.
A 1:200 dilution of a patient's sample was made and 336 red cells were counted in
an area of 0.2 mm^2. What is the RBC count?
A. 1.68 × 1012/L
B. 3.36 × 1012/L
C. 4.47 × 1012/L
D. 6.66 × 1012/L - ANSWER: B. RBC count = number of cells counted × dilution
factor × depth factor (10), divided by the area.
In this example, 336 × 200 × 10 = 672,000 ÷ 0.2 = 3.36 ×
106/mm^3 = 3.36 × 10^12/L.
What phagocytic cells produce lysozymes that are bacteriocidal?
A. Eosinophils
B. Lymphocytes
C. Platelets
D. Neutrophils - ANSWER: D. Neutrophils are highly phagocytic and release
lysozymes, peroxidase, and pyrogenic proteins.
Eosinophils migrate to sites where there is an allergic reaction or parasitic
infestation, releasing peroxidase, pyrogens, and other enzymes, including an oxidase
that neutralizes histamine. They are poorly phagocytic and do not release lysozyme.
If a patient has a reticulocyte count of 7% and an Hct of 20%, what is the corrected
reticulocyte count?
A. 1.4%
, B. 3.1%
C. 3.5%
D. 14% - ANSWER: B. In anemic states, the reticulocyte percentage is not
a true measure of reticulocyte production. The following formula must be applied to
calculate the
corrected (for anemia) reticulocyte count. Corrected
reticulocyte count = reticulocytes (%) × Hct ÷ 45, the
average normal Hct. In this case, 7 × (20 ÷ 45) = 3.1.
A decreased osmotic fragility test would be associated with which of the following
conditions?
A. Sickle cell anemia
B. Hereditary spherocytosis
C. Hemolytic disease of the newborn
D. Acquired hemolytic anemia - ANSWER: A. Osmotic fragility is decreased when
numerous sickle
cells and target cells are present and is increased in
the presence of spherocytes. Spherocytes are a prominent feature of hereditary
spherocytosis (HS),
hemolytic disease of the newborn, and acquired hemolytic anemia. The osmotic
fragility test is increased in the presence of spherocytes, whereas this test is
decreased when sickle cells, target cells, and other poikilocytes are present.
What effect would using a buffer at pH 6.0 have on a Wright's-stained smear?
A. Red cells would be stained too pink
B. White cell cytoplasm would be stained too blue
C. Red cells would be stained too blue
D. Red cells would lyse on the slide - ANSWER: A. The pH of the buffer is critical in
Romanowsky stains.
When the pH is too low (<6.4), the red cells take up more acid dye (eosin), becoming
too pink. Leukocytes also show poor nuclear detail when the pH is decreased.
Which of the following erythrocyte inclusions can be visualized with supravital stain
but cannot be detected on a Wright's-stained blood smear?
A. Basophilic stippling
B. Heinz bodies
C. Howell-Jolly bodies
D. Siderotic granules - ANSWER: B. Heinz bodies are irregular, refractile, purple
inclusions that are not visible with Wright's stain but show up with supravital
staining. The other three inclusions can be detected with Wright's stain.
A falsely elevated Hct is obtained. Which of the following calculated values will not
be affected?
EXAM 400 QUESTIONS AND CORRECT DETAILED
ANSWERS WITH RATIONALES (VERIFIED ANSWERS) |
ALREADY GRADED A+
Insufficient centrifugation will result in:
A. A false increase in hematocrit (Hct) value
B. A false decrease in Hct value
C. No effect on Hct value
D. All of these options, depending on the patient - ANSWER: A. Insufficient
centrifugation does not pack down the
red blood cells; therefore, the Hct, which is the
volume of packed cells, will increase.
Variation in red cell size observed on the peripheral smear is described as:
A. Anisocytosis
B. Hypochromia
C. Poikilocytosis
D. Pleocytosis - ANSWER: A. A mature erythrocyte is approximately 7-8 μm in
diameter. Variation in normal size is denoted by the
term anisocytosis. Hypochromia is a term that indicates increased central pallor in
erythrocytes, and poikilocytosis denotes variation in red cell shape.
Which of the following is the preferable site for bone marrow aspiration and biopsy
in an adult?
A. Iliac crest
B. Sternum
C. Tibia
D. Spinous processes of a vertebra - ANSWER: A. The iliac crest is the most
frequently used site for
bone marrow aspiration and biopsy. This site is the
safest and most easily accessible, with the bone just
beneath the skin, and neither blood vessels nor
nerves are in the vicinity.
Mean cell volume (MCV) is calculated using the following formula:
A. (Hgb / RBC) × 10
B. (Hct / RBC) × 10
C. (Hct / Hgb) × 100
D. (Hgb / RBC) × 100 - ANSWER: B. MCV is the average "volume" of the red cells. This
is
,obtained by dividing the Hct or packed cell volume
(PCV) by the red blood cell (RBC) count in millions per
microliter of blood and multiplying by 10. The MCV is
expressed in cubic microns (μm3) or femtoliters (fL).
What term describes the change in shape of erythrocytes seen on a Wright's-stained
peripheral blood smear?
A. Poikilocytosis
B. Anisocytosis
C. Hypochromia
D. Polychromasia - ANSWER: A. Variation in shape of the erythrocytes on a
peripheral
blood smear is poikilocytosis. Anisocytosis refers to a
change in size. Hypochromia is an increase in central
pallor in erythrocytes. Polychromasia describes the bluish tinge of the immature
erythrocytes (reticulocytes) circulating in the peripheral blood.
Calculate the mean cell hemoglobin concentration (MCHC) using the following
values:
Hgb: 15 g/dL (150 g/L)
Hct: 47 mL/dL (0.47)
RBC: 4.50 × 106/μL (4.50 × 1012/L)
A. 9.5% (.095)
B. 10.4% (.104)
C. 31.9% (.319)
D. 33.3% (.333) - ANSWER: C. MCHC is the average concentration of Hgb in red
cells expressed as a percentage. It expresses the ratio of the weight of Hgb to the
volume of erythrocytes and is calculated by dividing Hgb by the Hct, and then
multiplying by 100. A decreased MCHC indicates that cells are hypochromic. In this
example, (15 ÷ 47) × 100 = 31.9%. The reference range for MCHC is 32%-36%.
A manual white blood cell (WBC) count was performed. A total of 36 cells were
counted in all 9-mm^2 squares of a Neubauer-ruled hemacytometer. A 1:10 dilution
was used. What is the WBC count?
A. 0.4 × 10^9/L
B. 2.5 × 10^9/L
C. 4.0 × 10^9/L
D. 8.0 × 10^9/L - ANSWER: A. The formula used for calculating manual cell counts
using a hemacytometer is:
Number of cells counted × dilution factor × depth factor (10) divided by the area.
In this example, 36 × 10 × 10 = 3600 ÷ 9 = 400/mm^3 or 0.4 × 10^9/L.
,When an erythrocyte containing iron granules is stained with Prussian blue, the cell
is called a:
A. Spherocyte
B. Leptocyte
C. Schistocyte
D. Siderocyte - ANSWER: D. Siderocytes are red cells containing iron granules
and are visible when stained with Prussian blue.
A 7.0-mL ethylenediaminetetraacetic acid (EDTA) tube is received in the laboratory
containing only 2.0 mL of blood. If the laboratory is using manual techniques, which
of the following tests will most likely be erroneous?
A. RBC count
B. Hemoglobin (Hgb)
C. Hct
D. WBC count - ANSWER: C. Excessive anticoagulant causes shrinkage of cells;
thus, the Hct will be affected. RBC and WBC counts
remain the same, as does the Hgb content.
A 1:200 dilution of a patient's sample was made and 336 red cells were counted in
an area of 0.2 mm^2. What is the RBC count?
A. 1.68 × 1012/L
B. 3.36 × 1012/L
C. 4.47 × 1012/L
D. 6.66 × 1012/L - ANSWER: B. RBC count = number of cells counted × dilution
factor × depth factor (10), divided by the area.
In this example, 336 × 200 × 10 = 672,000 ÷ 0.2 = 3.36 ×
106/mm^3 = 3.36 × 10^12/L.
What phagocytic cells produce lysozymes that are bacteriocidal?
A. Eosinophils
B. Lymphocytes
C. Platelets
D. Neutrophils - ANSWER: D. Neutrophils are highly phagocytic and release
lysozymes, peroxidase, and pyrogenic proteins.
Eosinophils migrate to sites where there is an allergic reaction or parasitic
infestation, releasing peroxidase, pyrogens, and other enzymes, including an oxidase
that neutralizes histamine. They are poorly phagocytic and do not release lysozyme.
If a patient has a reticulocyte count of 7% and an Hct of 20%, what is the corrected
reticulocyte count?
A. 1.4%
, B. 3.1%
C. 3.5%
D. 14% - ANSWER: B. In anemic states, the reticulocyte percentage is not
a true measure of reticulocyte production. The following formula must be applied to
calculate the
corrected (for anemia) reticulocyte count. Corrected
reticulocyte count = reticulocytes (%) × Hct ÷ 45, the
average normal Hct. In this case, 7 × (20 ÷ 45) = 3.1.
A decreased osmotic fragility test would be associated with which of the following
conditions?
A. Sickle cell anemia
B. Hereditary spherocytosis
C. Hemolytic disease of the newborn
D. Acquired hemolytic anemia - ANSWER: A. Osmotic fragility is decreased when
numerous sickle
cells and target cells are present and is increased in
the presence of spherocytes. Spherocytes are a prominent feature of hereditary
spherocytosis (HS),
hemolytic disease of the newborn, and acquired hemolytic anemia. The osmotic
fragility test is increased in the presence of spherocytes, whereas this test is
decreased when sickle cells, target cells, and other poikilocytes are present.
What effect would using a buffer at pH 6.0 have on a Wright's-stained smear?
A. Red cells would be stained too pink
B. White cell cytoplasm would be stained too blue
C. Red cells would be stained too blue
D. Red cells would lyse on the slide - ANSWER: A. The pH of the buffer is critical in
Romanowsky stains.
When the pH is too low (<6.4), the red cells take up more acid dye (eosin), becoming
too pink. Leukocytes also show poor nuclear detail when the pH is decreased.
Which of the following erythrocyte inclusions can be visualized with supravital stain
but cannot be detected on a Wright's-stained blood smear?
A. Basophilic stippling
B. Heinz bodies
C. Howell-Jolly bodies
D. Siderotic granules - ANSWER: B. Heinz bodies are irregular, refractile, purple
inclusions that are not visible with Wright's stain but show up with supravital
staining. The other three inclusions can be detected with Wright's stain.
A falsely elevated Hct is obtained. Which of the following calculated values will not
be affected?
