Manual Cell Count Flashcards
Why is manual cell counting necessary? (Principle)
May be necessary to use manual methods when counts exceed the linearity of an instrument, when an instrument is nonfunctional and there is no backup, in remote laboratories in Third World countries, or in a disaster situation when testing is done in the field
Manual cell counts are performed using?
Hemacytometer, or counting chamber, and manual dilutions made with calibrated, automated pipettes and diluents (commercially available or laboratory prepared).
The principle for the performance of cell counts is essentially the same for white blood cells (WBCs), red blood cells (RBCs), and platelet. However, they vary in?
dilution, diluting fluid, and area counted
What is the most common hemacytometer used?
Levy chamber with improved Neubauer ruling. Or the Improved Neubauer Counting Chamber/ Hemacytometer
The Improved Neubauer Hemacytometer is composed of two raised surfaces, each with?
a 3 mm x 3 mm square counting area or grid (total area 9 mm2)
The two chambers of the Improved Neubauer Hemacytometer is separated by?
an H-shaped moat
Each of the four corner
(WBC) squares is subdivided further into?
16 squares
The center square subdivided into ___ squares. And each of this square is further subdivided into ____
25 intermediary squares; 16 small squares
The distance between each counting surface and the coverslip is
0.1 mm (reciprocal is 10)
The total volume of one entire grid or counting area on one side of the hemacytometer is?
0.9 mm^3
Cite the general formula for manual cell counts.
Total count = cells counted x dilution factor /
area (mm^2 ) x depth (0.1)
or
Total count = cells counted x dilution factor x 10* / area (mm^2)
If one mm^3 is equivalent to one microliter (uL). How do you convert the count per uL to the count per liter (L)?
by multiplying uL by a factor of 10^6 or by 1,000,000,000
It refers to the number of WBCs in 1 liter (L) or 1 microliter (uL) of blood.
WBC or leukocyte count
Why is the diluting fluid of the WBC count hypotonic?
The diluting fluid lyses the nonnucleated red blood cells in the sample to prevent their interference in the count
The typical dilution of blood for the WBC
count is
1:20
Prior to cell counting, how do you clean the hemocytometer and coverslip that will be used?
You clean the hemacytometer and coverslip with alcohol and dry thoroughly with a lint-free tissue.
WBC counts should be performed within?
3 hours of dilution
When charging or filling both sides of the hemacytometer you hold the microhematocrit tube at a ____ angle and touch the tip to the coverslip edge where it meets the chamber floor
45-degree
What is the method used when counting cells under the microscope?
Battlement
How do you count all the cells (WBCs, RBCs, and Platelets) in the hemacytometer?
For WBC count- four corner squares.
For RBC count- five squares (four corner squares and the center square) in the center square of the grid.
For Platelet count- 25 small squares in the center square of the grid.
What is the preferred objective lens used for each cell count (WBCs, RBCs, Platelet).
For WBC count- LPF (10X objective lens, 100x total magnification).
For RBC count- HPF (40x objective lens, 400x total magnification)
For Platelet count- HPF (40x objective lens, 400x total magnification)
What type of microscope is used in Platelet cell count?
Phase-contrast microscope. A light microscope can also be used, but visualizing the platelets may be more difficult.
If the difference between the total cells counted on each side is more than 10% what does this indicates?
Indicates an uneven distribution, which requires that the procedure be repeated.
In WBC cell count, if 1:100 dilution was being utilized, how many squares/ area should you count?
9 large squares or 9 mm2 on both sides of the chamber
