Peripheral blood smear
A stained film of blood examined under a microscope to assess the number, appearance, and proportions of blood cells.
Wedge smear method: A technique that spreads a drop of blood into a thin film using the edge of a second slide. It creates the thin, feathered film used for routine manual blood-cell review.
Anemia: A condition in which blood has reduced oxygen-carrying capacity, often because of low hemoglobin or red-cell mass. Red-cell size, color, and shape help characterize its underlying pattern.
Red blood cell: A hemoglobin-containing blood cell that transports oxygen and carbon dioxide. Its size, central pallor, and shape dominate routine film assessment.
Automated hematology analyzer: An instrument that measures and classifies blood cells using electronic, optical, or flow-based methods. It rapidly counts cells, while the smear permits direct visual inspection.
Preanalytical variation: Changes introduced before laboratory analysis by collection, transport, storage, or specimen handling. Delay and handling can distort cells before they reach the microscope.
Wright stain: An acidic and basic dye mixture used to distinguish structures in blood cells. Its contrasting colors make cell types and intracellular details visible.
Leukemia: A group of cancers arising from blood-forming tissues that produce abnormal blood cells. Circulating blasts or atypical white cells may prompt urgent investigation.
White blood cell: A blood cell involved in immune defense and inflammation. Its types and maturation stages are classified during film review.
Flow cytometry: A technique that characterizes cells in suspension by measuring light scattering and fluorescent signals. It provides marker-based cell analysis beyond routine stained-film morphology.
Interobserver variability: Differences in judgments made by separate observers assessing the same material. Manual cell classification can vary between trained reviewers.