1.A blood collection and diluting system is first assembled.
2.To gain access to the diluting solution, the reservoir seal needs is punctured.
3.A finger is lanced and a small drop of blood is allowed to accumulate.
4.Blood is drawn into the pipette.
5.Blood in the pipette is transferred to the diluting reservoir, which contains a solution (= 0.9% saline) that is isotonic for blood cells and prevents them rupturing (= cell lysis). Usually, there is enough fluid in the reservoir to dilute the blood by a factor of 200-400 times, and the dilution factor (df) is provided by the manufacturer.
6.The reservoir and pipette are converted into a dropper assembly by removing the pipette from the reservoir and reseating it in the reverse position.
7.A coverslip is placed on a hemacytometer, and the dropper assembly is carefully positioned next to the coverslip. A few drops of solution is then squeezed from the reservoir.
8.The hemacytometer draws a set amount of solution under the coverslip. Usually this is limited to depth of 0.1 mm.
9.Etched in the hemacytometer is a counting grid, which appears under magnification.
10.Five grid squares are used to count RBCs.
Fluid volume/grid square = 0.004 〖mm〗^3 (or 0.2 mm × 0.2 mm × 0.1 mm).
Total volume counted = 0.020 〖mm〗^3(or 5 × 0.004 〖mm〗^3).
11.All RBCs in each grid squares are counted.
Total RBC count = RBCs counted in 5 squares × volume correction factor (VCF)× dilution factor (DF).
VCF = 0.1 〖mm〗^3/ 0.020 〖mm〗^3
DF = 200 to 400 ×