Blood smear. In this test, a drop of blood is spread (smeared) on a slide and stained with a special dye. The slide is then examined under a microscope. The numbers, size, and shape of red blood cells, white blood cells, and platelets are recorded. Blood cells with unusual shapes or sizes can help diagnose many blood diseases, such as leukemia, malaria, or sickle cell anemia.
This is part of the CBC – Complete Blood Count Test.