Where on the blood smear would you select to start your WBC differential count?

Where on the blood smear would you select to start your WBC differential count?

• A. Thickest area
• B. Monocellular layer
• C. Feathered edge
• D. Thinnest area

Answer: (B)

When performing a WBC differential, you start in the monolayer—the area where cells are in a single, even layer with minimal overlapping. This gives the clearest view of nuclear and cytoplasmic features needed to accurately identify different white blood cells. Beginning at the feathered edge or in the thickest area leads to artifactual appearances and overlapping cells, which obscure morphology and make counting unreliable. The thinnest area may have too few cells to provide a representative differential. So the best starting point is the monolayer, where cells are evenly distributed and can be distinguished clearly.

When performing a WBC differential, you start in the monolayer—the area where cells are in a single, even layer with minimal overlapping. This gives the clearest view of nuclear and cytoplasmic features needed to accurately identify different white blood cells. Beginning at the feathered edge or in the thickest area leads to artifactual appearances and overlapping cells, which obscure morphology and make counting unreliable. The thinnest area may have too few cells to provide a representative differential. So the best starting point is the monolayer, where cells are evenly distributed and can be distinguished clearly.