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Sputum MicroscopyAka: Sputum Cytology, Sputum Gram Stain

See Also
1. Sputum Collection
2. Sputum Gross Exam
Assessing Sputum Sample Quality
1. Ideal Sputum Sample for Culture
  1. Under 10 squamous epithelial cell per low power field
  2. Many Neutrophils present (>5 per high power field)
  3. Bronchial epithelial cells present
  4. Alveolar Macrophages may be present
2. Inadequate Sputum Sample
  1. Over 25 squamous epithelial cells/LPM
Sputum Sample Preparation
1. Pull strand or plug of Sputum onto slide
2. Consider buffered crystal violet to stain cells
3. Apply cover slip
4. View under oil immersion
Cytology Stains
1. No Stain
  1. Blastomycosis
  2. Cryptococcosis
2. Gram Stain
  1. Gram Positive Bacteria
  2. Candida
  3. Tuberculosis (weakly Gram Positive)
  4. Nocardia (weakly Gram Positive)
3. Direct Fluorescent Antibody Staining
  1. Legionella
4. Wright stain or Giemsa Stain
  1. Intracellular organisms
Special Staining Circumstances
1. Acid-fast Mycobacteria (Tuberculosis)
  1. Ziehl-Neelsen Stain (Red against blue background)
  2. Kinyoun stain
    1. Less reliable than Ziehl-Neelsen stain
    2. Results in quickly stained sample
  3. Fluorochrome dyes (auramine, rhodamine)
    1. Higher false positive rate than Ziehl-Neelsen stain
    2. Assist greatly in identifying organisms
2. Fungal Organisms
  1. PAS staining or Methenamine silver staining
    1. Histoplasmosis
    2. Coccidioidomycosis
    3. Aspergillus
    4. Mucor
  2. KOH Preparation
Microscopic findings
1. Caseous masses
2. Dittrich's plugs
3. Curschmann's spirals (Asthma)
4. Charcot-Leyden Crystals (Asthma)
5. Bronchial casts
6. Concretions
7. Broncholith
  1. Calcified particles as seen in Broncholithiasis
8. Lung Cancer cells
  1. Central bronchus tumors
  2. May require 4 samples to detect
9. Eosinophils (>5%): identified with Wright's Stain
  1. Allergy
  2. Asthma

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This page was written by Scott Moses, MD. This page was last revised before 5/10/08, prior to consistent tracking of revision date. This page was last published on 5/10/2008. Please send comments and questions to the editor. Contact information may be found on the page About the Family Practice Notebook. These pages are best viewed with Microsoft Internet Explorer 6.0.