The white blood cell (WBC) count is a useful diagnostic tool that is frequently given to patients who may have an infection or other disease. By preparing a sample of blood and counting the number of cells, a WBC count helps reveal the number of WBCs per microliter (mcL).
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Things you need
- Antiseptic Wipe
- Elastic band
- Needle & Tube
- Turk's Solution
Obtain Blood Sample. Blood should only be drawn by qualified professionals. Before drawing blood, use an antiseptic wipe to clean an area on the inside of the elbow. Tying an elastic band around the upper arm will help increase the pressure in the lower arm and cause the vein to swell. Use a needle and collection tube or vial to draw blood from the vein. Upon collecting the blood, the needle can be removed.
Prepare the slide. The blood sample (of a known volume) must be diluted, then treated with Turk's solution. Turk's solution contains acetic acid, which breaks down the red blood cells, and dye, which stains the WBCs.
Count the WBCs. Using a microscope, count the number of WBCs in the defined volume of blood. According to the Merck manual, counting should be conducted with a x10 objective lens. WBCs should be counted in the four large corner squares because their sides measure 1mm. For quality purposes, it is helpful to repeat the count. Different counts should not have a difference of more than 15%.
Calculate the WBC. In a solution that was diluted 1:10, the number of WBCs in the four squares should be multiplied by 10 twice, then divided by four [ (WBC x 10 x 10)/4 ] = [ WBC x 25 ].
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