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Peripheral smear

CBC Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: CBC

Overview

A peripheral blood smear (peripheral smear) is a microscopic examination of a thin film of blood on a glass slide stained to show red blood cells (RBCs), white blood cells (WBCs) and platelets. The test evaluates cell size, shape, color, inclusion bodies, differential WBC morphology and platelet appearance—information not apparent from automated counts. It helps identify types of anemia (microcytic, macrocytic, hemolytic), infections, leukemias, platelet disorders, blood parasites and red cell fragmentation. Indications include unexplained fatigue, pallor, bleeding/bruising, fever, abnormal automated CBC or suspected hemolysis. Results may vary with age (newborns and infants have different WBC differentials), pregnancy, chronic illness and some ethnic/genetic conditions (thalassemia, hereditary spherocytosis).

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Test Preparation

No special preparation is required
Clinical history is required

Why Do I Need This Test

Profile: Included in the CBC (complete blood count) workup or ordered as a reflex when CBC flags abnormalities - Symptoms: fatigue, pallor, fever, bleeding, bruising, unexplained cytopenias or leukocytosis - Diagnoses/monitoring: anemia classification, hemolysis, infection, leukemia, parasitic disease, platelet disorders - Reasons for abnormal smear: nutritional deficiencies, bone marrow disorders, autoimmune processes, infections, medications, toxins - Biological meaning: abnormal shapes/patterns indicate underlying mechanism (hemolysis, marrow response, infiltration) - Behaviors: alcohol use, poor diet, certain drugs can alter morphology - Family history: hereditary hemoglobinopathies or membrane disorders warrant smear evaluation

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Understanding Test Results

A normal smear shows predominantly normocytic, normochromic RBCs and a WBC differential within the ranges above.
Microcytosis (small RBCs) suggests iron deficiency or thalassemia; macrocytosis (large RBCs) suggests B12/folate deficiency, liver disease or alcohol effect.
Schistocytes/split RBCs (>1% of RBCs) indicate microangiopathic hemolysis (TTP/HUS/DIC).
Spherocytes point to autoimmune or hereditary hemolysis.
Target cells and basophilic stippling suggest thalassemia or lead poisoning.
Hypersegmented neutrophils indicate megaloblastic anemia.
Presence of blasts or circulating immature myeloid/lymphoid cells is abnormal—any blasts on peripheral smear is concerning for leukemia and needs urgent evaluation (higher counts increase likelihood of acute leukemia).
Marked neutrophilia (>70%) with left shift suggests bacterial infection or inflammation; lymphocytosis (>50–60%) suggests viral infection or chronic lymphoproliferative disorders.
Significant platelet clumping or markedly reduced platelets on smear requires correlation with automated counts to rule out pseudothrombocytopenia or true thrombocytopenia (risk for bleeding).

Normal Range

Neutrophils: 40-60 Lymphocytes: 20-40 Monocytes: 2-8 Eosinophils: 1-4 Basophils: 0.5-1 RBC morphology: normocytic, normochromic; minimal anisocytosis/poikilocytosis Platelets: adequate number; normal size (≈2–4 μm); no clumping

FAQs

Q: What is a peripheral smear test?

A: A peripheral smear test (peripheral blood smear) examines a thin stained blood film under a microscope. It assesses red cell size, shape and color, white cell types and platelet number/appearance. The test helps diagnose anaemia types, infections, haemolysis, blood cell disorders (like leukemia) and platelet problems, and monitors treatment or blood cell changes not detected by automated analyzers.

Q: What is a normal peripheral smear report?

A: A normal peripheral blood smear shows uniform, round, normocytic, normochromic red blood cells without significant anisocytosis or poikilocytosis; a normal white blood cell differential with expected proportions of neutrophils, lymphocytes, monocytes, eosinophils and basophils; adequate platelets in number and size without clumping; and no immature or abnormal cells, parasites, or intracellular inclusions.

Q: What is the difference between a CBC and a peripheral smear?

A: A complete blood count (CBC) is an automated quantitative test reporting red and white cell counts, platelets, hemoglobin, hematocrit and red cell indices. A peripheral smear is a manual microscopic review of a stained blood film to assess cell morphology, detect abnormal cells, parasites or platelet clumping, and to confirm or explain CBC abnormalities. They are complementary tests.

Q: What are the indications for peripheral blood smear?

A: Peripheral blood smear is indicated for unexplained anemia, leukopenia or leukocytosis, thrombocytopenia or thrombocytosis; suspicion of hemolysis, blood‑borne parasites (e.g., malaria), or platelet/clotting disorders; abnormal CBC or automated differential; suspected hematologic malignancies or myelodysplastic syndromes; evaluation of febrile illness with cytopenias; monitoring therapy response, transfusion reactions, or confirming analyzer flags.

Q: How long does peripheral smear take?

A: A peripheral blood smear is quick to prepare and examine: smear and stain take about 10–20 minutes and microscopic review typically 15–45 minutes. Many laboratories provide preliminary findings the same day, with final reports usually within 24 hours for routine samples; urgent or inpatient smears can be reviewed and reported within a few hours.

Q: What is the cost of a peripheral smear test?

A: Costs vary by country and provider. In India private labs often charge roughly ₹200–800 (~$2.50–10). In the UK a peripheral smear is usually free on the NHS; private clinics may charge about £15–60. In the US, insurance often covers it (copay $0–50); uninsured out‑of‑pocket fees commonly run $20–150. Check local labs and your insurer for exact pricing.