WBC manual count using hemocytometer
IntroductionWBCs count is the count of leukocytes contained in 1 liter of blood
Expressed as WBCs/mm³
WBC is used to investigate infections & unexplained fever ,& to monitor treatment which can cause leucopenia.
Material
Blood sample (EDTA anticoagulated blood or capillary blood)WBCs diluting pipette
Diluting solution
Hemocytometer
microscope
The Hemacytometer
contains 2 Neubauer counting chamberEach chamber contains:
*4 WBC counting squares
*Each contains 16 squares
Methodolog
draw blood up to 0.5 marks on WBCs pipette and complete to 11 with WBCs diluting solution(Turk‘s solution).
Mix for 2-3 minute
Charge hemacytometer
Discard the first 4-5 drops
Place tip of the pipette at the edge central platform
Then let the hemacytometer to stand on the bench for 3-5 minute
Turk's solutionTürk's solution is a composed of a stain (Gentian violet) and 1-2% acetic acid. The solution destroys red blood cells within a blood sample, and stains the nuclei of the white blood cells, making them easier to see and count. Turk's Solution is intended for use in counting leukocytes in a defined volume of blood. Erythrocytes are hemolyzed while leukocytes are stained for easy visualization.
Calculation
Number of cells/mm³=
counted cells in 4 large square/ 4 x
diluting factor x
volume correction factor
The dilution factor=
total volume/sample volume= 11-1/0.5 =20
counted volume =
The total volume of the 1 large square== (width x length x depth )
= (1mm x 1mm x 1/10 mm) =1/10
Number of cells/mm³=
counted cells in 1 large square x
diluting factor x
volume correction factor.
Number of cells/mm³= n x20 x 10
= n x 200
Example
If total number of WBCs in 4 squares is 120
Then the number of WBCs in 1mm³=
120/ 4 x 200 =6000
Normal values of WBCs:
Newborn 9000-30000 cell/mm³
Adult 4000-11000 cell/mm³
Significance of the test
-Leukocytosis
*Occur as an indicator of body defense against foreign materials (bacteria, parasites, toxins)
*Metabolic disorders
*Chemical and drug poisoning
*Acute hemorrhage
