Peripheral Smear

Function

A Peripheral Smear (or Peripheral Blood Film) is a manual microscopic examination of a thin layer of blood spread on a glass slide. While automated machines count cells, the smear allows a trained pathologist to see the actual shape, size, and health of Red Blood Cells (RBCs), White Blood Cells (WBCs), and Platelets. It serves as a visual confirmation of automated CBC results.

Why it is Ordered

It is ordered when an automated CBC shows abnormal results, such as a very low platelet count or the presence of immature cells. It is also used to investigate suspected blood disorders, parasitic infections (like malaria), or unexplained jaundice and anemia.

Associated Conditions

• Sickle Cell Disease: Identified by the characteristic sickle-shaped RBCs.
• Leukemia: Suggested by the presence of 'blasts' (immature, cancerous white cells).
• Malaria: The parasites can be seen directly inside the red blood cells.
• Thalassemia: Indicated by 'target cells' and significant variation in cell size.
• Hemolytic Anemia: Characterized by fragmented red cells (schistocytes).

Clinical Value

This test provides information that machines often miss, such as the specific way platelets clump together or the presence of subtle inclusions within cells that indicate lead poisoning or specific vitamin deficiencies.