Fiberoptic bronchoscopy examines the main airways for the presence of cancer or a foreign body. In this hospital procedure, the doctor suppresses the patient's gag reflex by spraying anesthetic into the throat. After light sedation, the doctor inserts the fiberoptic bronchoscope into either the nose or the mouth and passes it down the throat into the trachea and then into each lung. There are no pain fibers in the tracheobronchial tree, so the procedure is painless. Tissue for diagnosis can be obtained either by brushing, washing or biopsy.