Average No. of
Platelets per X100 Field Platelet Count Estimate
Figure 20.7 Three zones of wedge preparation.
1. WBCs should contain a blue nucleus along with a lighter staining cytoplasm.
2. RBCs should have good quality of color ranging from buff pink to orange.
3. Platelets should be blue with granules and no nucleus.
5 to 8 100,000 to 160,000
10 to 15 200,000 to 300,000
16 to 20 320,000 to 400,000
Observations Under X10
1. Place a well-stained slide on the stage of the microscope, smear side up, and focus using the low-power objective (X10).
2. Check to see if there are good counting areas available free of ragged edges and cell clumps.
3. Check the WBC distribution over the smear.
4. Check that the slide is properly stained.
5. Check for the presence of large platelets, platelet clumps, and fibrin strands.
Observations Under X40 x-: WBC Estimates
1. Place a drop of immersion oil on the slide and change the objective to X50 oil. (In cases where no X50 is available, use the X40 high dry with no oil.)
2. Choose a portion of the peripheral smear where there is only slight overlapping of the RBCs. Count 10 fields, take the total number of white cells and divide by 10, and refer to Table 20.1 to determine the WBC estimate.
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