A laboratory test that provides information about the number, type, and shape of blood cells; also known as a peripheral smear or differential stain. Once a blood sample has been drawn, the number of white and red blood cells relative to other types of blood cells is counted, any abnormalities in cell shape are noted, and the total number of white blood cells and platelets is roughly estimated. A blood smear also allows doctors to classify the blood by its color and by the shape and size of the cells. A blood smear may be performed as part of a routine health examination or when diagnosing an illness, particularly one that involves abnormally shaped blood cells.
A drop of (anticoagulated) whole blood spread thinly on a glass microscope slide so that blood cell types can be examined, counted, and characterized.