This is the procedure in which an instrument is introduced through the mouth or the nostril to examine the upper airway: nasal pharynx, oral pharynx, larynx, trachea and the bronchi. Biopsy and cell samples (sputum or bronchial washings) could be obtained and foreign body could be retrieved. In rigid bronchoscopy a metal tube is used. In fiberoptic bronchoscopy a flexible fiberoptic instrument is used. Laser excision of bronchial tumors is also performed through a bronchoscope. Material effects, risks and side effects: bleeding after biopsy; coughing; laryngospasm; aspiration; collapse of small airways; hypoxemia.