MODULE 2 AUTOMATION Flashcards
Two basic cell counting principles employed in most hematology analyzers
Electrical Impedance
Optical Scatter or Detection
What is Hydraulics
aspirating unit, dilutors, dispenser, mixing chambers, aperture baths, flow cells and hemoglobinometer
What is PNEUMATICS
Vacuums and pressure for opening valves and moving the sample through the system
What is ELECTRICAL SYSTEMS
Electronic analyzers and computing circuity for processing data
What is Electrical Impedance
Also know as low-voltage direct current resistance
most commonly methodology used
example are Coulter Counter and Sysmex Counter
Principle of Electrical Impedance
Cell passes through the aperture, cells do not conduct current but they change electrical resistance which is counted as voltage pulses.
Size Threshold Ranges in an Electrical Impedance Method
`RBCs 36-360 fL
WBCs 45-450 fL
Lymphocytes 45-90 fL
Monocytes 90-160 fL
Granulocytes 160-450 fL
Platelets 2-20 fL
Principle of OPTICAL SCATTER
Differentiate and enumerate cell types based on the scattering properties of the cells.
Patterns of scatter are measured in various angles
Uses laser and nonlaser light
What are the Patters of Scatters are measured by various angles
- Forward angle light source
- Side angle light scatter
What is Forward angle light scatter
measure cell size
What is Side angle light scatter
Measures cell granularity and lobularity
Side angle light scatter consist of
a. RBC no nucleus
b. WBC with nucleus
Example of LIGHT used in Optical Scatter
a. Tungsten
b. Helium-neon laser
what is Tungsten
halogen lamp
Helium-neon Lamp
Laser monochrome light
What is a Laser Light
most common light source used in flow cytometers because of its properties INTENSITY, STABILITY and MONOCHROMATISM
Principle of FLOW CYTOMETRY
Cells suspension is run under high pressure in single, narrow stream of laser, causing excitation of flourescent compounds resulting emission of light energy. Energy is detected by a photomultiplier tube and converted into computerized data, which provide information regarding the number, size and cellular components.
Major components of Flow Cytomers
Fluidics
Optics
Electronics
What is FLUIDICS
flow chamber for single cell seperation, sheath fluid and hydrodynamic focusing
what is OPTICS
excitation of light source includes lasers or lamps.
Light is seperated by dichroic mirror and filters
example of lasers
argon
krypton
Helium-neon
helium cadium
diode
(KAHHD)
examples of Lamps
Mercury
Xenon-mercury
(MX)
what is Electronics
Photomultuplier tube detecs light energy, then converts this to voltage pulses, computers translate pulses into data files.
Benefits of Optical Technology
Laser Light can be focused on individual cells
More than 2 measurements can be made and more information can be gathered
Cells are passed in a single file through the flow cells
More realistic results
Principle of histogram
utilizes impedance technology and representation of cell number versus one measured property, usually cell size.
Produced by plotting the number on the y axis and cell size on the x axis
How many distribution peaks is the Normal WBC Histogram
3 Distribution Peaks
First Peak WBC Histogram
45-90 fL: small mononuclear cells (lymphocytes
Second Peak WBC Histogram
90-160 fL: minor population of large mononuclear cells (monocytes, reactive lymphocytes, immature WBCs)
Third Peak WBC Histogram
160-450 fL: normal mature types of granulocytes
WBC categories on Coulter Counter
Small Cells (lymphocytes)
Medium Cells (Reactive lymphocytes)
Large Cells (Granulocytes)
Abnormal WBC Histogram
Enumerate Abnormal WBC Histogram
R1: <35 fL indicate nRBCs, giant and clumped platelets
R2: 90 fL indicate Reactive lymhocytes or blast cells
R3: 160 fL indicate increase in bands, immature neutrophils, eosinophils or basophils
R4: >450 fL indicate high granulocyte and multiple region overlap (RM)
Enumerate Abnormal WBC Histogram
R1: <35 fL indicate nRBCs, giant and clumped platelets
R2: 90 fL indicate Reactive lymhocytes or blast cells
R3: 160 fL indicate increase in bands, immature neutrophils, eosinophils or basophils
R4: >450 fL indicate high granulocyte and multiple region overlap (RM)
Abnormal WBC Histogram
Other flags in WBC Histogram
H: parameter value is higher than set normal limit
L: parameter value is lower than set normal limit
Other flags in WBC Histogram
H: parameter value is higher than set normal limit
L: parameter value is lower than set normal limit
Abnormal WBC Histogram
RBC Histogram
6-360 fL or >36 fL
Show single peak at between 70 and 110 fL
Abnormal RBC Histogram Interpretation
24-36 fL Reject (RBC Histogram can measure cells as small as 24 fL)
Shift to the Right: Macrocytic
Shift to the Left: Microcytic
Bimodal, 2 Peaks: Cold agglutinin, hemolytic anemia with schistocytes present, anemia with different cell size (when patient present blood transfusion, dimorphic RBC population)
Increased Curved Width: Anisocytosis (correlate with increase RDW)
WBC Histogram
24-36 fL Reject (RBC Histogram can measure cells as small as 24 fL)
Shift to the Right: Macrocytic
Shift to the Left: Microcytic
Bimodal, 2 Peaks: Cold agglutinin, hemolytic anemia with schistocytes present, anemia with different cell size (when patient present blood transfusion
WBC Histogram
24-36 fL Reject (RBC Histogram can measure cells as small as 24 fL)
Shift to the Right: Macrocytic
Shift to the Left: Microcytic
Bimodal, 2 Peaks: Cold agglutinin, hemolytic anemia with schistocytes present, anemia with different cell size (when patient present blood transfusion
WBC Histogram
24-36 fL Reject (RBC Histogram can measure cells as small as 24 fL)
Shift to the Right: Macrocytic
Shift to the Left: Microcytic
Bimodal, 2 Peaks: Cold agglutinin, hemolytic anemia with schistocytes present, anemia with different cell size (when patient present blood transfusion
Platelet Histogram
2-20 fL
Platelet Histogram Interpretation
Lower Region Interference: <2 fL Electrical Impedence
Upper Rehion Interference: >20 fL Microcytic RBCs, Schistocytes, Giant or Clumped Platelets
Abnormal RBC Histogram Interpretation
Scattergram
also called CYTOGRAM OR SCATTERPLOT
2-dimensional representation of 2 or more cell properties or characteristics plotted against each other
Scattergram
also called CYTOGRAM OR SCATTERPLOT
2-dimensional representation of 2 or more cell properties or characteristics plotted against each other
Scatter plots for WBC
Displayed on a monitor and colored coded for different subpopulations
Methodologies of Scattergram
Radiofrequency
Fluorescence
Cytochemistry
Problems Encountered in Automated Methods
Instrumental Errors
Nature of the Specimen
Example of Instrumental Error
Positive Errors
negative Errors
Improper Settings of aperture current/threshold
What is a Positive Errors
Aperture
Examples Positive Errors
Aperture plug- most common problem in cell counting
Bubbles in the sample- cause by vigorous mixing
Extraneous electrical pulses
Example of Negative Errors
Excessive lysing of RBCs
Example of Improper setting of aperture current/threshold
cause either + or - errors
Example of Nature of specimen error
Giant platelets
Fragment of WBC cytoplasm may be counted as RBCs or Platelets
Agglutination of RBCs, WBCs and Platelets
Platelet Sattelitism
Effect of Giant Platelets in Nature of Specimen Errors
Effect of Giant Platelets in Nature of Specimen Errors
counted as RBCs or WBCs
Effect of Giant Platelets in Nature of Specimen Errors
counted as RBCs or WBCs
Effect of Fragment of WBC Cytoplasm in Nature of Specimen Errors
Effect of Fragment of WBC Cytoplasm in Nature of Specimen Errors
counted as RBCs or Platelets
Effect of Agglutination of RBCs, WBCs and Platelets in Nature of Specimen Errors
False-negative results for each count
Effect of Fragment of WBC Cytoplasm in Nature of Specimen Errors
counted as RBCs or Platelets
Effect of Agglutination of RBCs, WBCs and Platelets in Nature of Specimen Errors
False-negative results for each count
Effect of Platelets Satellitism in Nature of Specimen Errors
Falsely low platelets count
Cold agglutinins Parameters Affected
INCREASE: MCV, MCHC
DECREASE: RBC
Grainy Appearance
Corrective action for Cold Agglutinins
warm specimen 37 degree Celsius and RERUN
Corrective action for Cold Agglutinins
warm specimen 37 degree Celsius and RERUN
Lipemia Icterus Parameters Affected
Lipemia Icterus Parameters Affected
INCREASE: Hb, MCH
Corrective action for Cold Agglutinins
warm specimen 37 degree Celsius and RERUN
Lipemia Icterus Parameters Affected
INCREASE: Hb, MCH
Lipemia Icterus Parameters Affected
Hemolysis Parameters Affected
DECREASE: RBC, Hct
Corrective action Lipemia Icterus
Plasma replacement
Corrective action Hemolysis
Request new specimen
Lysis-resistant RBCs Parameters Affected
INCREASE: WBC, Hb
Corrective action Lysis-resistant RBCs
Perform manual dilution, allow incubation time for lysis
Microcytes or Schistocytes Parameters Affected
INCREASE: PLT
DECREASE: RBC
Corrective action for Microcytes or Schistocytes
review blood film
nRCS, Megakaryocytes fragments or Micromegakaryoblasts Parameters Affected
INCREASE: WBC (older specimen)
Corrective action for nRCS, Megakaryocytes fragments or Micromegakaryoblasts
Newer instruments
Count nRBCs and correct WBC count
Count micromegakaryoblasts per 100 WBCs and correct
Platelets Clumps Parameters Affected
INCREASE: WBC
DECREASE: PLT
Corrective action for Platelets Clumps
Redraw specimen in Sodium Citrate, multiply result by 1.1
WBC, 100.000/mL Parameters Affected
INCREASE: Hb, RBC, Hct
Corrective action for WBC, 100.000/mL
Manual Hct
Manual Hb
Leukemia, especially with chemotherapy Parameters Affected
INCREASE: PLT
DECREASE: WBC
Corrective action for Leukemia, especially with chemotherapy
Review film
Perform phase platelet count or CD61 count
Old Specimen Parameters Affected
INCREASE: MCV, MPV
DECREASE: PLT
Corrective action for Old Specimen
establish stability and specimen rejection criteria
Lyse resistance abnormal RBCs
Sickle Cells
Target Cells
Hypochromic Cells
(STH)
Criteria to repeat the analysis if
Rule of 3 failures on a normochromic sample
Any results outside linearity limits established by the manufacturer- dilute into linearity range
unexplained delta check failures
Effect of Agglutination of RBCs, WBCs and Platelets in Nature of Specimen Errors
False-negative results for each count
Criteria to repeat the analysis if
Rule of 3 failures on a normochromic sample
Any results outside linearity limits established by the manufacturer- dilute into linearity range
unexplained delta check failures
Effect of Agglutination of RBCs, WBCs and Platelets in Nature of Specimen Errors
False-negative results for each count