peripheral blood film

A peripheral blood film (peripheral blood smear) is a thin layer of blood spread on a glass slide, stained and examined under a microscope to evaluate blood cell appearance and distribution. It shows red cell size and shape, white cell types and abnormalities, and platelet number and morphology, helping detect anemia, infections, blood cancers and platelet disorders and complementing automated counts.

Peripheral blood film helps diagnose anemia types (iron‑deficiency, megaloblastic, hemolytic including spherocytosis), hemoglobinopathies (thalassemia, sickle cell), leukemias and marrow disorders (myelodysplasia, myelofibrosis), infections (malaria, babesiosis), microangiopathic hemolytic anemia (DIC, TTP with schistocytes), platelet disorders and reactive changes from severe infection or sepsis, paroxysmal nocturnal hemoglobinuria, leukoerythroblastic pictures from marrow infiltration, and eosinophilia or lymphocytosis suggesting allergic or viral processes.

A doctor orders a peripheral blood smear to visually examine red and white blood cells and platelets for size, shape and abnormalities. It helps diagnose and classify anemias, hemolysis, infections (e.g., malaria), blood cancers (leukemia), platelet disorders and unexpected automated count results. Smears reveal cell inclusions, immature cells and parasites that guide further testing and treatment.

A normal peripheral blood smear shows normocytic, normochromic red cells without significant anisopoikilocytosis or abnormal inclusions; WBC differential: neutrophils 40–75%, lymphocytes 20–45%, monocytes 2–8%, eosinophils 1–4%, basophils 0–1%; platelets 150–450 ×10^9/L. Hemoglobin ~13.5–17.5 g/dL (men), 12.0–15.5 g/dL (women) with hematocrit ~41–53% (men), 36–46% (women). Interpretation considers age, sex and clinical context.

The purpose of a peripheral blood film (PBF) test is to examine a stained blood smear under a microscope to assess the size, shape, and appearance of red and white blood cells and platelets. It helps diagnose and classify anaemias, infections (including malaria), blood cancers (leukaemia), platelet disorders and hemoglobinopathies, monitors treatment response, and guides further laboratory tests and clinical management.

Collect fresh venous blood in an EDTA tube and mix gently. Place one small drop near the frosted end of a clean slide. Use a second spreader slide at a 30–45° angle to touch and draw the drop forward, then push smoothly to form a thin film with a feathered edge. Air-dry, then fix and stain (Wright/Giemsa). Label and examine promptly.