Bronchoalveolar Lavage (BAL):
Saline (or another fluid) is passed through a bronchoscope into a portion of the lung and then collected with suction for examination.  The procedure allows one to "wash out" a peripheral portion of the lung and send the fluid that is retrieved to the laboratory to look for evidence of an infection, cancer or other disease.  BAL provides a much more reliable specimen than the "sputum" that a person might expectorate.