Bronchoalveolar lavage (BAL) (otherwise called bronchoalveolar washing) is a symptomatic technique for the lower respiratory framework in which a bronchoscope is gone through the mouth or nose into a suitable aviation route in the lungs, with a deliberate measure of liquid presented and afterward gathered for assessment. This strategy is regularly performed to analyze pathogenic contaminations of the lower respiratory airways(leading to, for instance pneumonia and COVID-19), however it likewise has been appeared to have utility in diagnosing interstitial lung infection.