Other methods to obtain the specimen may include bronchoscopy and transtracheal aspiration .
Normal sputum contains epithelial cells from the lining of the respiratory tract.
Tumors within the respiratory tract may slough cells into the sputum. The specimen is prepared in the laboratory and examined under the microscope for the presence of abnormal cells. Rinse your mouth with water to avoid contamination by particles from the mouth. Cough deeply from the lungs after taking several deep breaths. One teaspoon of sputum is needed for the test.