Sputum examination precautions are as follows: 1, control the amount of sputum: generally do not need a particularly large amount of sputum, the sputum sent for examination needs to use a special container, usually for 3-5 mouthfuls of sputum volume. The amount of sputum is not less than 2ml, and it is enough to ensure the amount of 3-5 smears; 2. Ensure the freshness of sputum: usually the first sputum in the morning, and send the sputum for examination in time after it is coughed up, especially in hot weather when the container needs to be kept clean and produced in time; 3. Patients need to have sputum testing for 3 consecutive days to ensure the relatively stable morphology of the production, and 1 day may not be completely representative and more contingent; 4. When the sputum is obviously thick, such as yellow thick sputum or yellow pus sputum, antibiotics are required for treatment. Antibiotics may control inflammatory secondary changes such as exudate, more mucus, or interfering degenerative cells, minimizing inflammatory changes. Patients need to be treated with antibiotics for 3-5 days before performing relevant sputum cytology, which can reflect the most basic, clear and primitive state of the respiratory system, especially in the case of tumorigenic lesions, which facilitates sputum cytology observation after reducing inflammatory disturbances.