Pediatric Bronchoalveolar Lavage (BAL) Guidelines

Pre‑procedure Imaging

High‑resolution computed tomography (HRCT) should be performed within 6 weeks before BAL to locate the optimal lung segment for sampling. 1
Ground‑glass opacities on HRCT are strongly associated with alveolar lymphocytosis and improve diagnostic yield of BAL. 1
Differential cell counts obtained from BAL vary significantly between lobes, especially for lymphocytes, underscoring the importance of targeted segment selection. 1

Persistent radiographic abnormalities—such as recurrent or persistent atelectasis, recurrent pneumonia, lingering infiltrates, or mass‑like lesions—are accepted indications for BAL. 2
BAL is indicated to obtain pulmonary specimens for microbiological analysis and to exclude aspiration or interstitial lung disease. 2
In children with atypical chronic cough and normal imaging who do not respond to medical therapy, BAL helps rule out micro‑aspiration. 2

Alveolar filling disorders (e.g., pulmonary alveolar proteinosis, lipoid pneumonia) may be treated with therapeutic BAL. 2
Removal of obstructive mucus plugs or intrabronchial blood clots causing atelectasis is an accepted therapeutic use of BAL. 2

Use a flexible bronchoscope with an outer diameter of 2.2–2.7 mm for neonates; larger diameters are selected for older children. 3
In ventilated patients, the bronchoscope may be introduced through an appropriately sized endotracheal tube or tracheostomy. 2
Position the bronchoscope in a wedge (cuña) within the chosen bronchopulmonary segment before instillation. 1
Instill normal saline at room temperature in a total volume of 100–300 mL, divided into 3–5 aliquots. 1
After each aliquot, aspirate immediately using negative suction pressure < 100 mmHg, adjusting pressure to avoid visible airway collapse. 1
Aim for a total fluid return > 30 % of the instilled volume; a minimum return of 5 % is required—if the return is < 5 %, the procedure should be aborted to prevent fluid overload. 1
Collect at least 5 mL of pooled BAL fluid for cellular analysis (optimal 10–20 mL). 1

Collect BAL fluid in containers that minimize cellular adhesion (e.g., silicone‑coated glass, polypropylene, or other tissue‑culture‑compatible plastics). 1
If the laboratory is on‑site with minimal delay, transport the sample “fresh” at ambient temperature. 1
For a transport delay of 30–60 minutes, keep the sample on ice (≈ 4 °C). 1
When delivery will exceed 1 hour, centrifuge the cells and avoid transporting the sample in the original saline solution. 1

A progressively bloodier appearance in sequential aliquots suggests diffuse acute alveolar hemorrhage. 1
A milky or beige‑brown, turbid fluid that forms flocculent sediment within 15–20 minutes is highly suggestive of pulmonary alveolar proteinosis. 1

Abort the procedure if fluid return falls below 5 % of the instilled volume to avoid pulmonary fluid overload. 1
Continuously monitor suction pressure to prevent airway collapse during aspiration. 1
Do not perform HRCT more than 6 weeks before BAL, as parenchymal changes may evolve and affect targeting. 1
Cease further fluid instillation if return remains consistently < 5 %, as this increases procedural risk. 1
Do not transport BAL samples in the original saline solution when the anticipated delivery time exceeds 1 hour; instead, process (e.g., centrifuge) the specimen prior to transport. 1

The European Respiratory Society recommends using a standard suction catheter that fits through the endotracheal tube without fully occluding the lumen. 4
Continuous monitoring of heart rate, oxygen saturation, blood pressure, and temperature should be maintained throughout the procedure. 4
A warm environment must be provided to prevent hypothermia, which neonates are especially prone to during invasive procedures. 4

The catheter is advanced blindly through the endotracheal tube until resistance is felt, indicating wedging in a distal bronchus (usually the right lower lobe). This blind insertion distinguishes mini‑BAL from bronchoscopic BAL. 4
The entire insertion‑to‑withdrawal sequence should be completed within 10–45 seconds, as tolerated by the infant. 4

After the maneuver, clinicians should watch for apnea, hypoxia, and bradycardia during the immediate post‑procedure period. 4
An arterial blood gas sample should be obtained after the procedure, and ventilator settings adjusted based on the results. 4

Mini‑BAL is primarily performed to collect respiratory specimens for microbiological analysis to rule out infection in ventilated neonates. 5

The European Respiratory Society notes that mini‑BAL can be employed therapeutically to remove mucus plugs that cause atelectasis in ventilated neonates. 6

Blind catheter insertion (mini‑BAL) remains the preferred method for obtaining lung secretions in critically ill neonates because it is simple to perform at the bedside and minimizes physiological compromise. 4