Which device is used to count leukocytes during manual counting?

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

Answer: (A)

Manual counting of leukocytes relies on a hemocytometer. This is a glass slide with a precise grid and a defined chamber depth, so each counted field represents a known volume. After diluting the blood with an appropriate diluent, you load the sample into the chamber and count white cells in the specified squares under a microscope. Because the volume is fixed, the total leukocyte concentration per microliter is calculated by applying the dilution factor to the count. This is distinct from using hematocrit tubes, which measure packed red cells, or a PCV reader, which reads packed cell volume rather than counting white cells. The standard tool for manual WBC counts is the hemocytometer (often the Neubauer chamber).