Deck 39: Automated Cell-Counting Instrumentation

Question 1

How do Beckman Coulter and Abbott instruments count red cells and platelets?

A) Florescent staining and enumeration
B) Survival staining and conductivity
C) Optical scatter
D) Electrical impedance

Answer 1

Electrical impedance

Question 2

What does the pneumatic system of cell counters do?

A) Operates the valves and moves the sample
B) Controls computer software
C) Digitizes the pulses generated by cell passage
D) Controls the laser light

Answer 2

Operates the valves and moves the sample

Question 3

What technology minimizes the problems of a rigid aperture including protein buildup, coincidence, and a single cell being counted twice?

A) Forward scatter
B) Radiofrequency
C) Hydrodynamic focusing
D) Fluorescence

Answer 3

Hydrodynamic focusing

Question 4

What principle does the Sysmex SE-9000/9500 use to analyze and separate white cell populations?

A) Electronic impedance
B) Optical light scatter
C) Volume, conductivity, and scatter
D) Low-frequency direct current and high-frequency current

Question 5

Select the most appropriate action for the results in Question 18:

A) Report the results.
B) Lyse the red cells manually and rerun.
C) Warm sample to 37 $\degree$ C and rerun.
D) Replace plasma with saline and rerun.

Question 6

An elevated immature reticulocyte fraction is associated with:

A) Bone marrow suppression
B) Chemotherapy
C) Bone marrow response to anemia
D) Renal disease

Question 7

Which of the following uses a peroxidase stain channel?

A) Siemens Healthcare Diagnostics ADVIA 2120
B) Coulter LH750
C) Sysmex SE-9000
D) Abbott CELL-DYN 4000

Question 8

What is the greatest limitation of automated cell counters?

A) Poor precision
B) Speed
C) Unavailability of quality control materials
D) Inherent specimen problems leading to occasional spurious results

Question 9

A patient sample comes off an automated cell counter with a failure of the red cell "rule of three." The red count is lower than expected given the hemoglobin. The MCV, MCH, and MCHC are elevated. Which of the following is the most likely reason for this failure?

A) Megaloblastic anemia
B) Lyse-resistant red cells
C) Cold agglutinin
D) Lipemia

Question 10

Which of the following is always calculated on cell counters?

A) Hematocrit
B) MCV
C) Mean cell hemoglobin concentration (MCHC)
D) Red count

Question 11

Which of the following is true regarding automated reticulocyte counts?

A) This was one of the earlier cell-counting methods to be automated.
B) Ribonucleic acid (RNA) is stained with various dyes that allow for detection of reticulocytes by optical scatter or fluorescence.
C) They are more accurate but less precise than the manual method.
D) They require significantly more time to count reticulocytes than manual methods.

Question 12

Platelet clumps would most likely interfere with which other automated parameter?

A) WBC count
B) RBC
C) Hemoglobin
D) Red cell indices

Question 13

Compared with manual methods, automated reticulocyte counting improved which of the following?

A) Distribution error
B) Statistical sampling error
C) Interobserver error
D) All of the above

Question 14

Which of the following is determined by light transmission between 525 and 555 nm?

A) Reticulocytes
B) Hemoglobin
C) Mean cell volume (MCV)
D) Mean cell hemoglobin (MCH)

Question 15

How do CELL-DYN instruments differentiate red cells and platelets from one another?

A) Differences in forward scatter using optical light scatter principle
B) Use of a unique reagent that selectively lyses red cells while preserving platelets
C) Differences in volume (fL) using electrical impedance principle
D) Use of a unique reagent that selectively lyses platelets while preserving red cells

Question 16

Forward light scatter, when used in an instrument using the optical scatter principle, correlates with cell:

A) Granules
B) Size
C) Nuclear chromatin
D) Number

Question 17

Counting the number and size of electrical interferences created by blood cells as they pass through a small aperture is a description of which of the following principles?

A) Electronic impedance
B) Optical scatter
C) Conductivity
D) Laminar flow

Question 18

What is the mechanism for the three-part differential found in older Coulter machines or those designed for smaller laboratories?

A) Volume, conductivity, scatter
B) Multiangle polarized scatter separation
C) Peroxidase staining and light scatter
D) Impedance after cytoplasm shrinkage

Question 19

An automated hematology analyzer is used to evaluate a blood specimen. Which of the following, coming off the instrument, would require performance of a manual white cell differential as opposed to blood film review?

A) Flagged data
B) Suppression of automated differential data
C) Abnormal red cell indices
D) A slightly elevated platelet count

Question 20

All of the following will be invalid when lipemia is present in a blood sample except:

A) MCHC
B) MCV
C) MCH
D) Hemoglobin

Question 21

Which automatic hematology analyzer performs the white count (by both optical scatter and electrical impedance) and then compares the two as an internal quality control check?

A) Sysmex 9000/9500
B) Coulter LH750
C) CELL-DYN 4000
D) Advia 2100

Question 22

What is the recommended method for establishing accuracy of automated hematology analyzers?

A) Use at least three levels of controls for calibration.
B) Use whole blood calibration methodology.
C) Use commercially prepared whole blood calibrators.
D) Perform manual methods for comparison.

Question 23

Platelet volume normally:

A) Is 15 to 20 fL
B) Increases as the sample sits in ethylenediaminetetraacetic acid (EDTA)
C) Is 5 to 18 fL
D) Is not reliable on most electronic instruments

Question 24

When the electronic impedance principle is used to count blood cells, what is done to increase platelet-counting sensitivity?

A) Decrease the size of the RBC/platelet aperture.
B) Increase the size of the RBC/platelet aperture.
C) Use a strong lysing agent to selectively lyse the RBCs.
D) Lower the upper threshold for counting platelets so that even microcytic red cells are excluded.

Question 25

A patient's white blood count comes off an automated cell counter as 380 * 10⁹/L. Which of the following could be reported without any additional testing?

A) Red blood count
B) Hemoglobin
C) Hematocrit
D) Platelet count

Question 26

Which of the following occurs if testing is not performed with 24 hours from specimen collection?

A) White blood count rises
B) WBCs deteriorate and RBCs swell
C) Hemoglobin rises
D) MCV decreases