Fiberoptic bronchoscopy is a procedure which involves passing a pencil-thin tube into the lung in order to collect fluid and cells from the airways. Fiberoptic bronchoscopy can collect cells from the walls of airways by gently brushing them (bronchial brushing). In addition, squirting small amounts of sterile water in to the airway and gently suctioning it back into the bronchoscope (bronchoalveolar lavage) collects cells.