HEMA Harr Flashcards
(161 cards)
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
A. A false increase in hematocrit (Hct) value
Explanation: 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
A. Anisocytosis
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
A. Iliac crest
Explanation: 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
B. (Hct ÷ RBC) × 10
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
A. Poikilocytosis
Explanation: 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)
C. 31.9% (.319)
Explanation: 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-mm2 squares of a Neubauer-ruled hemacytometer. A 1:10 dilution was used. What is the WBC count?
A. 0.4 × 109/L
B. 2.5 × 109/L
C. 4.0 × 109/L
D. 8.0 × 109/L
A. 0.4 × 109/L
Explanation: 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/mm3 or 0.4 × 109/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
D. Siderocyte
explanation: 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
C. Hct
explanation: 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 mm2. 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
B. 3.36 × 1012/L
Explanation:
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/mm3 = 3.36 × 1012/L.
What phagocytic cells produce lysozymes that are bacteriocidal?
A. Eosinophils
B. Lymphocytes
C. Platelets
D. Neutrophils
D. Neutrophils
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%
B. 3.1%
Explanation: 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
A. Sickle cell anemia
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
A. Red cells would be stained too pink
Explanation: 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
B. Heinz bodies
Explanation: 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?
A. MCV
B. MCH
C. MCHC
D. Red cell distribution width (RDW)
B. MCH
A Miller disk is an ocular device used to facilitate counting of:
A. Platelets
B. Reticulocytes
C. Sickle cells
D. Nucleated red blood cells (NRBCs)
B. Reticulocytes
SITUATION: RBC indices obtained on an anemic patient are as follows: MCV 88 μm3 (fL); MCH 30 pg; MCHC 34% (.340). The RBCs on the peripheral smear would appear:
A. Microcytic, hypochromic
B. Microcytic, normochromic
C. Normocytic, normochromic
D. Normocytic, hypochromic
C. Normocytic, normochromic
All of the following factors may influence the erythrocyte sedimentation rate (ESR) except:
A. Blood drawn into a sodium citrate tube
B. Anisocytosis, poikilocytosis
C. Plasma proteins
D. Caliber of the tube
A. Blood drawn into a sodium citrate tube
What staining method is used most frequently to stain and manually count reticulocytes?
A. Immunofluorescence
B. Supravital staining
C. Romanowsky staining
D. Cytochemical staining
B. Supravital staining
The Coulter principle for counting of cells is based upon the fact that:
A. Isotonic solutions conduct electricity better than cells do
B. Conductivity varies proportionally to the number of cells
C. Cells conduct electricity better than saline does
D. Isotonic solutions cannot conduct electricity
A. Isotonic solutions conduct electricity better than cells do
A correction is necessary for WBC counts when nucleated RBCs are seen on the peripheral smear because:
A. The WBC count would be falsely lower
B. The RBC count is too low
C. Nucleated RBCs are counted as leukocytes
D. Nucleated RBCs are confused with giant platelets
C. Nucleated RBCs are counted as leukocytes
Using an electronic cell counter analyzer, an increased RDW should correlate with:
A. Spherocytosis
B. Anisocytosis
C. Leukocytosis
D. Presence of NRBCs
B. Anisocytosis
Given the following values, which set of red blood cell indices suggests spherocytosis?
A. MCV 76 μm3 MCH 19.9 pg MCHC 28.5%
B. MCV 90 μm3 MCH 30.5 pg MCHC 32.5%
C. MCV 80 μm3 MCH 36.5 pg MCHC 39.0%
D. MCV 81 μm3 MCH 29.0 pg MCHC 34.8%
C. MCV 80 μm3 MCH 36.5 pg MCHC 39.0%