What are the findings on a peripheral blood smear (PBS)?

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Last updated: April 28, 2025View editorial policy

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From the Guidelines

A peripheral blood smear should be reviewed for the presence of mast cells and/or evidence of an associated hematologic neoplasm, as recommended by the NCCN clinical practice guidelines in oncology 1. The peripheral blood smear is a crucial diagnostic tool that provides valuable information about the presence of mast cells, dysplasia, monocytosis, and/or eosinophilia in patients with suspected mast cell diseases.

  • The test involves examining the appearance of blood cells under a microscope, which helps identify specific cell morphologies associated with different diseases.
  • The procedure requires a small blood sample, typically drawn from a vein in the arm, and results are usually available within hours to a day.
  • According to the ASCO clinical practice guideline endorsement of the College of American Pathologists and American Society of Hematology guideline, a pathologist should review recent or concurrent CBC counts and leukocyte differentials and evaluate a peripheral blood smear 1.
  • The percentage of circulating mast cells should be reported in patients with mast cell leukemia, and the smear should be reviewed for features of an associated hematologic neoplasm.
  • The value of a peripheral blood smear lies in its ability to provide visual confirmation of abnormalities that automated analyzers might miss, allowing clinicians to identify specific cell morphologies associated with different diseases.
  • For accurate interpretation, the smear should be prepared properly and examined by trained laboratory professionals or hematologists.

From the Research

Purpose of Peripheral Blood Smear

  • A microscopic examination of an appropriately prepared and well-stained blood smear by a knowledgeable laboratory professional is necessary and clinically useful in a number of circumstances and for a variety of reasons 2
  • The Peripheral Blood Smear (PBS) examination plays an important role in evaluating hematological disorders, such as anemia 3
  • Peripheral blood smear examination is used to diagnose and evaluate suspected platelet-related disorders in children 4

Analysis of Peripheral Blood Smear

  • Manual analysis of peripheral blood smear is tedious, time-consuming, and prone to errors, requiring qualified laboratorians 3, 5
  • Automation of PBS analysis is an active field of research, with methods using image processing techniques being developed 3, 5
  • Image analysis consists of a sequence of steps, including image segmentation, features extraction and selection, and pattern classification 5

Applications of Peripheral Blood Smear

  • Anemia diagnosis using PBS 3
  • Evaluation of suspected platelet-related disorders in children 4
  • Verification of flagged automated hematology results and determination of the need for a manual differential leukocyte count 2
  • Provision of a complete hematologic picture of a case, including diagnosis or diagnostic clues 2

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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