Definition

Peripheral blood smear test is an examination of the solid components of blood, including red blood cells, white blood cells, and platelets. The purpose of this test is to analyze the size and shape of blood cells and estimate the count of white blood cells and platelets.

Indication

Peripheral blood smear is used to help diagnose and monitor various health conditions, including blood disorders, organ failures such as those affecting the kidneys or liver, and certain cancers. Some blood disorders that may be assessed through this test include:

• Anemia: A condition in which there are fewer red blood cells than normal, often caused by nutritional deficiencies.

• Leukopenia: A condition characterized by a reduced number of white blood cells.

• Thrombocytopenia: A condition where the platelet count is below normal levels.

• Leukocytosis: This condition involves an increased white blood cell count.

• Lymphocytosis: An elevation in the number of lymphocytes, a type of white blood cell.

• Certain cancers that affect the bone marrow.

Contraindication

There are no specific contraindications for peripheral blood smear. This is a safe and commonly used procedure.

Preparation Before the Test

No special preparation is required for peripheral blood smear. However, it is important to inform your doctor if you are taking any medications, as this could affect the results.

Test Procedure

The procedure for peripheral blood smear is straightforward. A healthcare professional will clean the skin on your arm with sterile alcohol and draw a small sample of blood from a vein using a sterile syringe. For infants, blood is typically drawn from the heel. The blood sample is then placed into a blood tube and sent to the laboratory, where it is examined under a microscope or specialized machine.

The risks associated with this test are minimal. Some individuals may experience minor pain, dizziness, or bruising at the site of the blood draw, but these symptoms usually resolve quickly.

Normal and Abnormal Value

Normal test results indicate that blood cells have the correct size, shape, and color. In a normal peripheral blood smear, the appearance of red blood cells and white blood cells should be distinguishable, with each having characteristic attributes. While normal values can slightly vary between laboratories, it is important to consult your doctor to interpret your specific results.

Red Blood Cells

Normal red blood cells are typically uniform in size, measuring between 7-8 µm in diameter. These cells lack a nucleus, which distinguishes them from other types of cells. Their shape is round and concave, resembling a donut with a slight depression in the middle. The hemoglobin contained within red blood cells gives them their characteristic pinkish color, with a paler center.

White Blood Cells

White blood cells test includes identifying the different types of leukocytes, each with distinct characteristics:

• Neutrophils: Measuring between 10-18 µm, neutrophils have cytoplasm containing pink or purple granules. They are the most abundant type of white blood cells and are essential for defending the body against infections.

• Eosinophils: These cells measure 10-15 µm and are identifiable by their large, orange-red granules. Eosinophils are typically found in small numbers (1-3%) and increase in response to parasitic infections or allergies.

• Basophils: With a size of 10-15 µm, basophils have large, dark purple granules. They are the least common white blood cell type, usually comprising about 1% of the total white blood cell count.

• Monocytes: Monocytes are the largest type of white blood cells, measuring between 12-20 µm. They play a key role in phagocytosis, which is the process of ingesting bacteria or foreign cells.

• Lymphocytes: Typically small, measuring 10-12 µm, lymphocytes have a small amount of cytoplasm and are round with a smooth surface. They are a critical part of the body’s immune response.

Results and Recommendations (Follow-up Tests)

If the test reveals abnormalities in the size, shape, or color of blood cells, further testing may be necessary to diagnose potential underlying conditions. Some possible causes of abnormal results red blood cells smear include:

• Anemia, including sickle cell anemia

• Thalassemia

• Bone marrow disorders

• Liver disease

• Cancer metastasizing to the bones

Abnormal white blood cell smear results can indicate conditions such as:

• Infections or inflammation

• Allergic reactions

• Leukemia

• Bone marrow disorders

Abnormal platelet smear results may suggest:

• Thrombocytopenia (a condition where there are too few platelets, leading to a higher risk of bleeding)

• Bernard-Soulier Syndrome

Consult the Right Doctor

If your peripheral blood count results are abnormal, you should consult with a general practitioner for diagnosis and treatment. For further evaluation, you may also need to see an internist. In pediatric cases, a pediatrician can provide more specialized care.

Looking for more information about laboratory, radiology, and other examination results? Click here!