Which device is primarily used to protect the accuracy of cell counts per microliter?

Which device is primarily used to protect the accuracy of cell counts per microliter?

• A. Hemocytometer
• B. Hematocrit tubes
• C. PCV card reader
• D. Standard WBC counting device

Answer: (A)

To obtain an accurate cell count per microliter, you need to count cells in a known, fixed volume. The hemocytometer provides that by using a standardized counting chamber with a precise depth (0.1 mm) and a grid etched into the surface. Each counted square corresponds to a specific volume (0.1 microliters), so counting cells in several squares and applying the dilution factor yields cells per microliter. Repeating across multiple squares reduces sampling error, giving a reliable concentration. Other devices don’t provide that fixed-volume counting framework. Hematocrit tubes measure packed cell volume, not cell concentration. A PCV card reader reads the packed volume value, not the number of cells per microliter. A standard WBC counting device may count cells but without the standardized chamber geometry, the results wouldn’t be as directly convertible to concentration.

To obtain an accurate cell count per microliter, you need to count cells in a known, fixed volume. The hemocytometer provides that by using a standardized counting chamber with a precise depth (0.1 mm) and a grid etched into the surface. Each counted square corresponds to a specific volume (0.1 microliters), so counting cells in several squares and applying the dilution factor yields cells per microliter. Repeating across multiple squares reduces sampling error, giving a reliable concentration.

Other devices don’t provide that fixed-volume counting framework. Hematocrit tubes measure packed cell volume, not cell concentration. A PCV card reader reads the packed volume value, not the number of cells per microliter. A standard WBC counting device may count cells but without the standardized chamber geometry, the results wouldn’t be as directly convertible to concentration.