Background The European Respiratory Society guidance on bronchoalveolar lavage (BAL) in children was published in 2000. It recommended taking one BAL specimen from the most affected lobe or from the right middle lobe in diffuse disease. In 2007, the European Respiratory Society modified the recommendations for children with cystic fibrosis (CF), suggesting two BAL specimens (right middle lobe and the lingula or the most affected lobe).

Objective To determine if BAL samples from one or two lobes give the full picture of lower airway infection in children with CF.

Design, setting and patients A retrospective review of all paediatric patients with CF who underwent flexible bronchoscopy between May 2007 and May 2009 was undertaken.

Main outcome measures As BAL specimens from all six lobes were collected, the BAL results were reviewed to identify if positive cultures would have been missed if only one lobe (right middle or most affected) or two lobes (right middle plus the lingula or most affected) had been sampled.

Results The results of 39 bronchoscopic procedures in 31 children were reviewed. The BAL samples were taken from 6 lobes in all 39 procedures. Had only one lobe been used, 26 positive cultures (14 organisms) would have been missed in 11 patients. Had two lobes been used, 12 positive cultures (8 organisms) would have been missed in 7 patients.

Conclusion A single-lobe BAL is insufficient in assessing patients with CF for lower airway infection. Even when BAL specimens are taken from two lobes, a number of infections may be missed.