Lecture 4 Flashcards
What is Electronic Impedance?
Also know as the Coulter Principle, provides a 3 part diff made of Histograms.
What is Optical Scatter?
5 part diff made of scatter plots.
The number of voltage pulse in the Electronic Impedance is proportional to the what?
Number of cells.
The size of voltage pulse in the Electronic Impedance is proportional to the what?
The Size or volume of the cells.
The x axis in a Electronic Impedance histogram is what?
Cell Size
The y axis in a Electronic Impedance histogram is what?
Relative number of cells
What size aperture is the WBCs and HgB measured in?
It is measured in a large WBC aperture.
What size aperture is RBCs and PLTs measured in?
A smaller RBC/PLT aperture.
What happens when Protein Buildup on an Aperture?
There is a decreases flow of cell thru aperture and a increases electrical resistance which falsely low cell counts with falsely high cell volumes.
What happens when Coincidence Passage (Coincidence Counting) accrues?
More than one cell pulled through aperture at one time, resulting in a falsely high cell volume.
What is a CBC Histogram?
It is a plot of the size distribution of WBCs, RBCs, and platelets.
What is shown in a histogram?
Average size of cells, Distribution of cells around a mean, and Presence of abnormal cell populations
How is the WBC aperture measured?
A lyseing agent is added to this aperture and the then the cells are measured spectrophotometically.
What is directly Measured?
RBC, WBC, and HgB
What is Derived from The Histogram?
PLT, MVP (Mean PLT Volume), MCV and RDW
What is computed?
HCT, MCH, and MCHC
What are the 2 populations on a WBC histogram?
Lymphs, Mid cells, and Granulocytes
R0
Clumped PLT, “Y-axis takeoff”
R1
Clumped PLT, “Y-axis takeoff”, and NRBC
R2
Blasts and Atypical (reactive) Lymphs
R3
Increased number of bands or eosinophils
R4
High absolute granulocyte counts
RM
Abnormalities in multiple regions
What can be estimated by looking at the RBC histogram by drawing a line from the peak to the X-axis.
MCV
What does a “Broad-based” RBC histograms mean?
Anisocytosis and Correlates with a high RDW
RBCs are sized as particles that are?
> = 36 fL
35-90 fL
Lymphs
90-160 fL
Mid cells
160-450 fL
Granulocytes
What is a Dimorphic RBC Population
Having two different populations of RBCs in the body at the same time and looks like a (Camel humps) because there are two RBC peaks on the histogram.
Platelets are sized as particles between?
2-20 fL
Interference in PLT counts
Dirt or debris in the diluent, Microcytic RBCs, Schistocytes (RBC fragments)
Tailing Up
MCV is very low, suspect microcytic RBCs are the cause.
What is a scatterplot?
It is a three-dimensional plot of cell populations. It is based upon VCS technology.
What is VCS technology?
Volume: Cell sizing by electrical impedance
Conductivity: Uses a high frequency electromagnetic probe which reflects the nuclear, granular, and chemical properties of cells.
Light scatter: Cell surfaces features and internal structure.
What gives you a 5 part diff?
A Scattergram or a Scatterplot
Which type of Scatterplot is most used.
DF-1 (Discriminant Function -1)
What is displayed on a DF-1?
X-axis: light scatter
Y-axis: volume
Basophils are not visible on DF-1 because they are located behind the lymphs.
what are the other 2 types of scatterplots?
DF-2 and DF-3
what are the Color Codes of the Scattergram?
Yellow (highest in number)
Red
Green
Blue (lowest in number)
Bull’s moving average can only be done on what cells and why?
RBC and because they useally do not change much.
What can Falsely increase a WBC count?
Heparin
NRBC
Platelet Clumps
What can Falsely Decrease a WBC count?
Clotted specimen
Smudge cells
What can Falsely increase a RBC count?
Giant platelet
Greatly elevated WBC
What can Falsely Decrease a RBC count?
Microcytic RBCs (counted as plts)
Cold agglutinins
Clotted specimens
What can Falsely increase a HgB count?
Lipemia
Greatly elevated WBC
What can Falsely increase a Hematocrit count?
Hyperglycemia (600 mg/dL or greater) (Glucose causes the RBCs to swell)
Greatly elevated WBC
What can Falsely increase a MCV count?
Hyperglycemia,
EDTA blood at room temperature > 6 hours
WBC > 50,000 WBC/uL
What can Falsely increase a PLT count?
Microcytic RBCs RBC fragments (schistocytes)
What can Falsely Decrease a HgB count?
Clotted specimen
What can Falsely Decrease a Hematocrit count?
Clotted specimen
Hemolysis
What can Falsely Decrease a PLT count?
Clotted specimen
Giant platelets counted as WBC
Platelet clumping, platelet satellitosis counted as WBC
What is a Pre-Analytical Sources of Error?
Anything that happens before it gets into the Instrument.
What is a Analytical Sources of Error?
Anything that happens while the test is being ran.
What is Post-Analytical Sources of Error
Anything that happens after the sample has been ran.
What are the 3 Types of Hematology Analyzers?
Beckman-Coulter
Sysmex
Cell-Dyn by Abbott Laboratories
Agglutination
Clumping of RBCs
