1.1 Basic Hematology Concepts and Laboratory Procedures Flashcards
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, depends on the patient
A. A false increase in hematocrit (Hct) value
Variation in red blood cell (RBC) size observed on the peripheral blood smear is described as:
A. Anisocytosis
B. Hypochromia
C. Poikilocytosis
D. Pleocytosis
A. Anisocytosis
A mature erythrocytes is approximately 7 to 8 um in diameter. Variation in normal size is denoted by the term anisocytois. Hypochromia is a term that indicates increases central pallor in erythrocytoes, and poikilocytosis denotes variation in RBC shape.
Which of the following is the preferred 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
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 being just beneath the skin, and neither blood vessels nor nerves are in the vicinity.
Mean cell volume (MCV) is calculated by using the following formula:
A. (Hgb ÷ RBC) x 10 where Hgb is hemoglobin in g/dL
B. (Hct ÷ RBC) x 10
C. (Hct ÷ Hgb) x 100
D. (Hgb ÷ RBC) x 100
B. (Hct ÷ RBC) x 10
MCV is the average “volume” of the RBCs. This is obtained by dividing the Hct or packed cell volume (PCV) by the RBC count in millions per microliter (uL) of blood and multiplying by 10. MCV is expressed in cubic microns (um^3) or femtoliters (fL).
What term describes the change in shape of erythrocytes seen on a Wright-stained peripheral blood smear?
A. Poikilocytosis
B. Anisocytosis
C. Hypochromia
D. Polychromasia
A. Poikilocytosis
Calculate the mean cell hemoglobin concentration (MCHC) by using the following values:
———————————————————-
Hgb: 15 g/dL (150 g/L)
Hct: 47 mL/dL (0.47)
RBC: 4.50 x 10^6 uL (4.50 x 10^12/L)
A. 9.5% (0.095)
B. 10.4% (0.104)
C. 31.9% (0.319)
D. 33.3% (0.333)
C. 31.9% (0.319)
MCHC is the average concentration of Hgb in RBCs expressed as percentage. It expresses the ratio of the weight of Hgb to the volume of erythrocytes and is calculated by dividing Hgb by Hct and then multiplying by 100. A decrease in MCHC indicates that cells are hypochromic. In this example, (15/ 47) x 100 =31.915 %. The reference range for MCHC is 32% to 36%.
A manual white blood cell (WBC) count was performed. In total 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 x 10^9/L
B. 2.5 x 10^9/L
C. 4.0 x 10^9/L
D. 8.0 x 10^9/L
A. 0.4 x 10^9/L
The formula used for calculating manual cells counts by using a hemacytometer is: Number of cells counted x dilution factor x depth factor (10) / area. In this example, 36 x 10 x 10 =3,600/9 =400/mm^3 or 0.4 x 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
D. Siderocyte
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. Hgb
C. Hct
D. WBC count
C. Hct
Excessive anticoagulant causes shrinkage of cells; thus, 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 RBCs were counted in an area of 0.2 mm^2. What is the RBC count?
A. 1.68 x 10^12/L
B. 3.36 x 10^12/L
C. 4.47 x 10^12/L
D. 6.66 x 10^12/L
B. 3.36 x 10^12/L
RBC count = number of cells counted x dilution factor x depth factor (10), / area. In this example, 336 x 200 x 10 =672,000 / 0.2 = 3.36 x 10^6/mm^3 = 3.36 x 10^12/L
What phagocytic cells produce lysozymes that are bacteriocidal?
A. Eosinophils
B. Lymphocytes
C. Platelets (PLTs)
D. Neutrophils
D. Neutrophils
If a patient has a reticulocyte count of 7% and Hct of 20%, what is the corrected reticulocyte count?
A. 1.4%
B. 3.1%
C. 3.5%
D. 14%
B. 3.1%
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 (%) x (Hct / 45) where 45 is the average normal Hct. In this case, 7 x (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 (HS)
C. Hemolytic disease of the fetus and newborn
D. Acquired hemolytic anemia
A. Sickle cell anemia
What effect would using a buffer at pH 6.0 have on a Wright-stained smear?
A. RBCs would be stained too pink
B. WBC cytoplasm would be stained too blue
C. RBCs would be stained too blue
D. RBCs would lyse on the slide
A. RBCs would be stained too pink
Which of the following erythrocyte inclusions can be visualized with supravital stain but cannot be detected on a Wright-stained blood smear?
A. Basophilic stippling
B. Heinz bodies
C. Howell-Jolly bodies
D. Siderotic granules
B. Heinz bodies
A falsely elevated Hct is obtained. Which of the following calculated values will not be affected?
A. MCV
B. Mean corpuscular hemoglobin (MCH)
C. MCHC
D. Red blood cell distribution width (RDW)
B. Mean corpuscular hemoglobin (MCH)
MCH= Hgb x 10/RBC count and is not affected by Hct. MCV = Hct x 10/RBC count, and MCHC = Hgb x 100/ Hct; therefore, an erroneous Hct will affect these parameters. Centrifugal force for microhematocrit determination should be 12,000 g for 5 minutes to avoid errors caused by trapped plasma. RDW is calculated by using electronic cell counters and reflects the variance in the size of the RBC population. Electronic cell counters calculate Hct from MCV and RBC count. Therefore, RDW would be affected by an erroneous MCV.
A Miller disk is an ocular device used to facilitate counting of:
A. PLT
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 um^3 (fL); MCH 30 pg; MCHC 34% (0.340). The RBCs on the peripheral blood 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 on 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 NRBCs are seen on the peripheral blood smear because:
A. The WBC count would be falsely lower
B. The RBC count is too low
C. NRBCs are counted as leukocytes
D. NRBCs are confused with giant PLTs
C. NRBCs 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 RBC indices suggests spherocytosis?
A. MCV 76 um^3 MCH 19.9 pg MCHC 28.5%
B. MCV 90 um^3 MCH 30.5 pg MCHC 32.5%
C. MCV 80 um^3 MCH 36.5 pg MCHC 39.0%
D. MCV 81 um^3 MCH 29.0 pg MCHC 34.8%
C. MCV 80 um^3 MCH 36.5 pg MCHC 39.0%
Spherocytes have decreased cell diameter and volume, and this results in loss of central pallor and discoid shape. The index most affected is MCHC, usually being in excess of 36%.
