 Bronchoalveolar lavage

Bronchoalveolar lavage (BAL) (also known as bronchoalveolar washing) is a diagnostic method of the lower respiratory system in which a bronchoscope is passed through the mouth or nose into an appropriate airway in the lungs, with a measured amount of fluid introduced and then collected for examination.This method is typically performed to diagnose pathogenic infections of the lower respiratory airways (leading to, for example pneumonia and COVID-19), though it also has been shown to have utility in diagnosing interstitial lung disease.