What type of blood sample is examined to count eosinophils?

Eosinophils are a type of white blood cell that are often counted during a complete blood count (CBC) as part of a peripheral blood sample. This sample contains all components of blood, including red blood cells, white blood cells, and platelets, and is obtained through venipuncture.

The examination of a peripheral blood sample allows for the identification and quantification of eosinophils, as well as other types of white blood cells. Eosinophils play a crucial role in the immune response, particularly in allergic reactions and parasitic infections, so their levels can provide important diagnostic information.

In contrast, plasma and serum samples do not contain cells, as they are the liquid components of blood after cells have been removed. Plasma contains clotting factors and proteins, whereas serum is the liquid that remains after blood has clotted. Bone marrow aspirate, while it can provide information about the production of blood cells, is not routinely used for counting eosinophils in peripheral blood; counting is typically done directly from the peripheral blood sample. Thus, utilizing a peripheral blood sample is the most appropriate method for evaluating eosinophil counts.