bronchoalveolar lavage (BAL)

Introduction

The collection of alveolar lavage specimens during bronchoscopy.

Indications

• pulmonary infection*
  • Pneumocystis carinii
  • tuberculosis
  • mycoses
  • other infections
• alveolar proteinosis
• pulmonary Langerhans cell granuloma
• lymphangitic pulmonary metastases (carcinomatosis)
• cell counts in diagnosis of parenchymal lung disease
• alveolar hemorrhage
• cytology for pulmonary neoplasm

* procedure of choice for assessment of infectious entities in pulmonary disease

Contraindications

• not useful for:
  • sarcoidosis
  • idiopathic pulmonary fibrosis
  • mass lesions, pulmonary nodules, lymphadenopathy

Laboratory

• microscopic examination
  • in normal persons, a BAL cell count shows 93% alveolar macrophages & 7% lymphocytes
  • granulocytes & macrophages are rarely observed in the absence of infectious pulmonary disease
• BAL CD4/CD8 ratio
  • reversed in patients with:
    • AIDS
    • lymphocytic interstitial pneumonitis
    • hypersensitivity pneumonitis (many)
  • increased in patients with sarcoidosis (non-specific)
• miscellaneous labs
  • protein in lower respiratory specimen

Procedure

• instillation of 100-150 mL of normal saline into the diseased segment(s) of the lung & aspirating the saline back via the bronchoscope
• the aspirated specimens can be examined under the microscope much as sputum may be analyzed

Notes

• contamination by upper airway flora may occur

More general terms

• bronchoscopic procedure
• lavage

Additional terms

• culture of bronchial or transtracheal aspirate/lavage
• sputum (phlegm)