automated analyzers (wk 11 study questions) Flashcards
3 benefits to the practice for using automated analyzers
Reduced labor costs
More complete information
Improved data reliability
Which of the automated cell counts are least accurate, RBC, WBC or Platelet?
platelet
Polycythemia
Increased number of RBCs; Accompanied by increased PCV and hemoglobin concentration
Anemia
Decrease in the oxygen-carrying capacity of the blood
three categories of analyzers
Impedance
Laser Flow Cytometry
Quantitative Buffy Coat Analysis System
Why should the CVT run regular quality control measures on the analyzer?
to ensure accuracy
Explain how impedance is used to count cells and how the machine can tell
an RBC from a WBC using this method
Passage of electric current across two electrodes separated by a glass tube with a small opening or aperture
Electrolyte fluid conducts the current.
Counting by moving a specific volume of cells in the electrolyte solution through the aperture by use of a vacuum or positive pressure
Cells are poor conductors and impede the flow of the current
Change in current is a function of cell size
disadvantages to using the impedance analyzer
Variation of cell size
Morphologic abnormalities not noted
Platelet clumping inaccuracies
Nucleated RBC inaccuracies
Quantitative Buffy Coat analysis system and its limitations
-Uses differential centrifugation and staining to estimate cells
-Uses specialized microhematocrit tube.
-Gives hematocrit value and estimates WBC and platelet concentrations
Limitation:
-Groups granulocytes and agranulocytes
-Left shift and Lymphopenia may go undetected
-Provides only estimates
Laser-based flow cytometer
Uses focused laser beams to evaluate the size and density; Cells scatter light differently
When would manual cell counts be performed?
avian and exotic practices
three advantages for running a CBC using the automated analyzer
-Faster than manual counts
-No operator bias
-More reproducible: counts more cells than manual
-Little training needed
disadvantages of running a CBC on the automated analyzer
-Clots, large platelets, and Nucleated RBCs can cause errors
-Can not pick up diagnostic changes in cell morphology
When should a blood smear be made and examined for a patient sample?
Recommended for all CBCs but definitely for sick patients
hematology analyzers
Impedance method:
-Cells pass through a charged aperture, disrupting the current
-Each interruption is counted
-The length of the interruption is proportional to cell size
-Chemical lysing agents are also used to help differentiate the cells
What are the graphs called that are shown on the results screen?
histogram
Dot plot
A visual representation of the CBC
What does the size and shape of the cloud on a dot plot tell us?
an indication of whether the cells of one type (i.e. the RBCs) are all similar in size or abnormally varied
What would the RBC dot plot look like if the patient was anemic?
very small
What would the WBC dot plot look like if the patient had neutrophilia?
larger
What can the dot plot tell you about abnormal cell morphology?
size only
doublets
Two discreet red blood cells that are in close proximity to one another when they are examined by the laser beam; mapped as one event but counted as two cells
RBC fragments
-Portions of red blood cell membranes from broken cells
-Particles have a similar size to platelets but refract light differently and are therefore located to the left of the platelet population
-Colored pink
uRBC
Unlysed RBC (colored orange)
