MLS HEMATOLOGY EXAM 2023-2024 /HEMATOLOGY
MLS ACTUAL EXAM 400 QUESTIONS AND CORRECT
DETAILED ANSWERS WITH RATIONALES (VERIFIED
ANSWERS) |ALREADY GRADED A+
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.
RATIONALE: 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. RDW – ….ANSWER….b.
RATIONALE: the MCH = Hb x 10/RBC count and is not affected by the Hct. The MCV
= Hct x 10/RBC count, and MCHC – Hb x 100/Hct; therefore, an erroneous Hct will affect
these parameters. Centrifugal force for microhematocrit determination should be 12,000
g for 5 min in order to avoid error caused by trapped plasma. The red cell distribution
width (RDW) is calculated by electronic cell counters and reflects the variance in the
size of the red cell population. Electronic cell counters calculate Hct from the MCV and
RBC count. Therefore, the RDW would be affected by an erroneous MCV
A Miller disk is an ocular device used to facilitate counting of:
a. platelets
b. reticulocytes
c. sickle cells
d. NRBCs – ….ANSWER….b.
RATIONALE: the manual reticulocyte count involves the counting of 1,000 RBCs. The
Miller disk is a reticle (grid) that is placed in the eyepiece of the microscope and divides
the field into two squares, one being nine times larger in size than the other.
Reticulocytes are enumerated in both the squares. Mature red cells are counted in the
smaller one
RBC indicies obtained on an anemic patient are as follows: MCV 88 um3 (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 – ….ANSWER….c.
RATIONALE: the MCV, MCH, and MCHC are all within the reference interval (normal
range); hence, the erythrocytes should be of normal size and should reflect normal
concentrations of Hb. Therefore, the anemia is 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 – ….ANSWER….a.
RATIONALE: EDTA and sodium citrate can be used without any effect on the eSR.
Anisocytosis and poikilocytosis may impede rouleaux formation, thus causing a low
ESR. Plasma proteins, especially fibrinogen and immunoglobulins, enhance rouleaux,
increasing the ESR. Reference ranges must be established for different caliber tubes
What staining method is used most frequently to stain and manually count
reticulocytes?
a. immunofluorescence
b. supravital staining
c. Romanowsky staining
d. cytochemical staining – ….ANSWER….b. RATIONALE:
the reticulum within the reticulocytes consists of RNA, which cannot be stained with
Wright’s stain. Supravital staining with new methylene blue is used to identify the
reticulocytes
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 – ….ANSWER….a.
RATIONALE: electronic cell (Coulter) counters use the principle of electrical impedance.
Two electrodes suspended in isotonic solutions are separated by a glass tube having a
small aperture. A vacuum is applied, and as a cell passes through the aperture it
impedes the flow of current and generates a voltage pulse
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 – ….ANSWER….c.
RATIONALE: the automated hematology analyzers enumerate all nucleated cells.
NRBCs are counted along with WBCs, falsely elevating the WBC count. To correct the
WBC count, determine the number of NRBCs per 100 WBCs. Corrected WBC count =
(uncorrected WBC count / [NRBCs + 100]) x 100
Using an electronic cell counter analyzer, an increased RDW should correlate with:
a. spherocytosis
b. anisocytosis
c. leukocytosis
d. presence of NRBCs – ….ANSWER….b.
RATIONALE:the RDW parameter correlates with the degree of anisocytosis seen on the
morphological examination. The RR is 11.5-14.5%
Given the following values, which set of RBC indices suggests spherocytosis?
a. MCV 76 MCH 19.9 MCHC 28.5%
b. MCV 90 MCH 30.5 MCHC 32.5%
c. MCV 80 MCH 36.5 MCHC 39.0%
d. MCV 81 MCH 29 MCHC 34.8% – ….ANSWER….c.
RATIONALE: spherocytes have a decreased cell diameter and volume, which results in
loss of central pallor and discoid shape. The index most affected is the MCHC, usually
being in excess of 36%
Which of the following statistical terms reflects the best index of precision when
comparing two CBC parameters?
a. mean
b. median
c. coefficient of variation
d. standard deviation – ….ANSWER….c.
RATIONALE: standard deviation(s) describes the distribution of a sample of
observations. It depends upon both the mean (average value) and dispersion of results
and is most influenced by reproducibility or precision. Because s is influenced by the
mean and expressed as a percentage of the mean, the coefficient of variation
([s/mean]x100) can be used to compare precision of tests with different means (e.g.
WBC and RBC counts or low vs high controls)
Which of the following is considered a normal hemoglobin?
a. carboxyhemogloibn
b. methemoglobin
c. sulfhemoglobin
d. deoxyhemoglobin – ….ANSWER….d. deoxyhemoglobin is the physiological Hb that
results form the unloading of oxygen by Hb.This is accompanied by the widening of the
space between beta chains and the binding of 2,3-DPG on a mole-for-mole basis
Which conditions will shift the oxyhemoglobin dissociation curve to the right?
a. acidosis
b. alkalosis
c. multiple blood transfusions
d. increased quantities of hemoglobin S or C – ….ANSWER….a. acidosis is associated
with a shift to the right of the oxyhemoglobin dissociation curve and, therefore,
increased oxygen release (decreased affinity of Hb for oxygen). Alkalosis does the
opposite. Multiple blood transfusions shift the curve to the left because the transfused
blood is low in 2,3-DPG. Hb S and Hb C do not change the affinity of oxygen fo
hemoglobin, however, many hemoglobinopathies do. For example, Hb Kansas causes a
right shift and Hb Chesapeake causes a left shift of the oxyhemoglobin dissociation
curve
What is the major type of leukocyte seen in the peripheral smear of a patient with
aplastic anemia?
a. segmented neutrophil
b. lymphocyte
c. monocyte
d. eosinophil – ….ANSWER….b. lymphocytes constitute the majority of the nucleated
cells seen. The bone marrow in aplastic anemia is spotty with patches of normal
cellularity. Absolute granulocytopenia is usually present, however, lymphocyte
production is less affected
What is the normal WBC differential lymphocyte percentage (range) in the adult
population?
a. 5-10%
b. 10-20%
c. 20-44%
d. 50-70% – ….ANSWER….c. the normal adult percentage of lymphocytes in a white cell
differential is between 20% and 44%, although normal ranges vary by institution, patient
population, and testing methodology. This range is higher in the pediatric population
In which age group would 60% lymphocytes be a normal finding?
a. 6 months-2 years
b. 4-6 years
c. 11-15 years
d. 40-60 years – ….ANSWER….a. there is a relative neutropenia in children from ages 4
months to 4 years. Because of this, the percentage of lymphocytes is increased in this
population. This is commonly referred to as a reversal in the normal differential
percentage (or inverted differential)
Which of the following results on an automated differential suggests that a peripheral
smear should be reviewed manually?
a. segs = 70%
b. band = 6%
c. mono = 15%