ASCP MLS Hematology Exam
Questions and Answers67
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 - ANSWERS -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 - ANSWERS -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 - ANSWERS -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.
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 - ANSWERS -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 - ANSWERS -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.
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) - ANSWERS -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 - ANSWERS -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 - ANSWERS -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 - ANSWERS -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.
Questions and Answers67
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 - ANSWERS -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 - ANSWERS -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 - ANSWERS -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.
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 - ANSWERS -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 - ANSWERS -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.
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) - ANSWERS -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 - ANSWERS -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 - ANSWERS -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 - ANSWERS -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.
