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Peripheral Blood Smear Interpretation Algorithm

Peripheral Blood Smear Interpretation Algorithm: Peripheral Blood Smear Review → Smear Quality Assessment → RBC Assessment → RBC Morphology Patterns → C...

Interactive Decision Tree

Mini Map

Algorithm Steps

  1. ▶
    Start

    Peripheral Blood Smear Review

    Systematic approach to blood film interpretation

    1. ◆
      Decision

      Smear Quality Assessment

      Evaluate technical adequacy

      • Good feathered edge
      • Monolayer zone present
      • No clotting or artifacts
      • Staining quality adequate
      1. ●
        Action

        RBC Assessment

        Evaluate red cell morphology

        • Size: Microcytic, normocytic, macrocytic
        • Shape: Spherocytes, elliptocytes, sickle cells, schistocytes
        • Color: Hypochromic, polychromatic
        • Inclusions: Howell-Jolly, basophilic stippling, parasites
        • Distribution: Rouleaux, agglutination
        1. ◆
          Decision

          RBC Morphology Patterns

          Recognize diagnostic patterns

          • Spherocytes → Hereditary spherocytosis, AIHA
          • Schistocytes → MAHA (TTP, HUS, DIC)
          • Target cells → Liver disease, hemoglobinopathy
          • Sickle cells → Sickle cell disease
          • Teardrop cells → Myelofibrosis
          1. ⚠
            Warning

            Critical/Urgent Findings

            Require immediate notification

            • Blasts present (possible leukemia)
            • >1% schistocytes (MAHA)
            • Malaria parasites
            • Extreme leukocytosis (>100K)
            • Marked thrombocytopenia with bleeding risk
            1. ●
              Action

              Correlate with CBC/Clinical

              Integrate findings

              • Match morphology with indices (MCV, MCH, MCHC)
              • Review clinical history
              • Consider additional testing: reticulocyte count, hemolysis labs
              • Recommend flow cytometry if abnormal WBCs
              • Suggest bone marrow if indicated
              1. ✓
                Outcome

                Issue Report

                Document findings and recommendations

      2. ●
        Action

        WBC Assessment

        Evaluate white cell morphology

        • Differential count estimation
        • Immature forms: Left shift, blasts
        • Toxic changes: Döhle bodies, toxic granulation, vacuoles
        • Atypical lymphocytes
        • Abnormal cells: Leukemia, lymphoma
        1. ◆
          Decision

          WBC Pattern Recognition

          Identify significant findings

          • Blasts >5% → Leukemia workup
          • Left shift → Infection, CML
          • Atypical lymphs → Viral (EBV, CMV), lymphoma
          • Monocytosis → CMML, chronic infection
          • Eosinophilia → Allergy, parasites, neoplasm
      3. ●
        Action

        Platelet Assessment

        Evaluate platelet morphology

        • Quantity: Adequate, increased, decreased
        • Size: Large platelets, giant platelets
        • Clumping: Pseudothrombocytopenia
        • Granulation: Hypogranular (MDS)
        • Exclude platelet satellitism

Guideline Source

ASCP Peripheral Blood Smear Review Guidelines

DOI: 10.1093/ajcp/aqz203View Guideline

Clinical Safety Information

Clinical Decision Support — Not a Substitute for Clinical Judgment

Individual patient factors may require deviation from these recommendations.

Known Limitations

  • Requires adequate smear quality for interpretation
  • Does not replace flow cytometry for leukemia diagnosis
  • Quantitative abnormalities need CBC correlation
  • Rare morphologies may require specialist review
  • Does not address bone marrow correlation

Applicable Regions

USAUUKEU

AU: RCPA guidelines

UK: NICE hematology pathways

US: ASCP and CAP guidelines

Version 1Next review: 2028-01-01

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Frequently Asked Questions

What is the Peripheral Blood Smear Interpretation Algorithm?

The Peripheral Blood Smear Interpretation Algorithm is a diagnostic clinical algorithm for Pathology. It provides a structured decision tree to guide clinical decision-making, based on ASCP Peripheral Blood Smear Review Guidelines.

What guideline is the Peripheral Blood Smear Interpretation Algorithm based on?

This algorithm is based on ASCP Peripheral Blood Smear Review Guidelines (DOI: 10.1093/ajcp/aqz203).

What are the limitations of the Peripheral Blood Smear Interpretation Algorithm?

Known limitations include: Requires adequate smear quality for interpretation; Does not replace flow cytometry for leukemia diagnosis; Quantitative abnormalities need CBC correlation; Rare morphologies may require specialist review; Does not address bone marrow correlation. Individual patient factors may require deviation from these recommendations.

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