Peripheral Blood Smear

A peripheral blood smear, also known as a blood film or smear, is a diagnostic test used to examine the components of blood under a microscope.

Purpose

The purpose of a peripheral blood smear is to:

• Diagnose and monitor various blood disorders, such as anemia, leukemia, and lymphoma
• Identify abnormalities in blood cells, including red blood cells, white blood cells, and platelets
• Detect infections, such as malaria or babesiosis, that affect the blood
• Monitor the effectiveness of treatments for blood disorders

Procedure

The procedure for a peripheral blood smear involves:

1. A healthcare professional drawing a sample of blood from a vein in the arm or finger
2. The blood sample being placed on a glass slide and spread into a thin layer using a special tool
3. The slide being allowed to air dry or fixed with a chemical solution to preserve the blood cells
4. The slide being stained with a dye, such as Wright's stain or Giemsa stain, to highlight the different components of the blood
5. The stained slide being examined under a microscope by a trained healthcare professional or laboratory technician

Components Examined

During a peripheral blood smear examination, the following components are typically evaluated:

• Red blood cells (RBCs): size, shape, color, and any abnormalities
• White blood cells (WBCs): type, number, and any abnormalities
• Platelets: number and any abnormalities
• Hematocrit: the proportion of RBCs in the blood

Abnormalities Detected

A peripheral blood smear can detect a range of abnormalities, including:

• Anisocytosis (unequal size of RBCs)
• Poikilocytosis (abnormal shape of RBCs)
• Leukocytosis (high WBC count) or leukopenia (low WBC count)
• Thrombocytosis (high platelet count) or thrombocytopenia (low platelet count)
• Blast cells or other abnormal cells that may indicate a blood disorder

Limitations and Risks

While a peripheral blood smear is a valuable diagnostic tool, it has some limitations and risks:

• May not detect all types of blood disorders or abnormalities
• Requires a skilled healthcare professional or laboratory technician to interpret the results accurately
• May cause temporary discomfort or bruising at the blood draw site
• May require additional testing, such as bone marrow biopsy or molecular analysis, to confirm a diagnosis