A hemacytometer is used to count cells in a precise volume of fluid.
(1) Load the hemacytometer with undiluted, well-mixed body fluid using a Pasteur pipette.
(2) Let the fluid settle for at least 10 minutes in a moist environment (Petri dish with moistened filter paper in the bottom).
(3) Count the red or white cells in 5 large squares (4 corner and center) on each of the 2 sides of the hemocytometer. The results of the 2 sides should be within 20% of each other; if not, repeat. According to convention, elements are counted if they lie on the topmost and leftmost lines, but not the bottommost or rightmost lines.
(4) Add the results of both sides together, giving a count over a total of 10 squares.
(1) No dilution factor needed.
(2) 10 squares have a volume of 10 * (0.1 cumm) = 1 cumm (microliter)
Therefore, the result of the 10 square count is the number of red or white blood cells per cumm (microliter).
If the number of large squares counted differs from 10, the equation is:
number of cells per cumm (microliter) =
= (total number of cells counted) / ((number of squares counted) * (0.1 cumm))
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Specialty: Hematology Oncology, Clinical Laboratory, Pulmonology, Surgery, general, Nephrology