Bronchial Lavage (BAL): Procedure, Indications, and Diagnostic Value

Bronchoalveolar lavage (BAL) is a diagnostic procedure performed during bronchoscopy to obtain cellular and fluid samples from the distal airways and alveoli for analysis.

Procedure Steps

1. Preparation: Consent, NPO, sedation (conscious/moderate), topical anesthesia (lidocaine) to nose/pharynx/larynx.
2. Bronchoscopy: Flexible bronchoscope passed via nose/mouth to target segment (usually right middle lobe or lingula).
3. Lavage: 100–300 mL sterile saline instilled in 20–50 mL aliquots; each aliquot gently aspirated.
4. Collection: First aliquot (proximal airway) discarded or kept separately; subsequent aliquots pooled for analysis.
5. Processing: Filtered, centrifuged; supernatant for cytokines/microbiology; cell pellet for cytology, flow cytometry, cultures.

Diagnostic Applications

Category	Examples
Infections	Pneumocystis, TB, fungi, viruses, bacteria (quantitative cultures)
Interstitial lung diseases	Hypersensitivity pneumonitis (lymphocytosis), sarcoidosis (CD4/CD8 ratio), NSIP, COP
Alveolar hemorrhage	Hemosiderin-laden macrophages (Goodpasture's, vasculitis)
Malignancy	Cytology for adenocarcinoma, lymphoma (flow cytometry)
Eosinophilic lung disease	Eosinophilia >25% (EP, ABPA, EGPA)
Transplant monitoring	Infection, rejection (lymphocytic bronchiolitis)

Therapeutic Use

• Mucus clearance in plastic bronchitis, cystic fibrosis (limited).
• Instillation of medications (surfactant, antibiotics, fibrinolytics) — experimental.

Safety

Generally safe. Transient fever, hypoxemia, bronchospasm common. Rare: significant bleeding, pneumothorax, respiratory failure. Contraindicated in severe hypoxemia, uncontrolled coagulopathy, hemodynamic instability.