Oral sputum is sputum, sputum is yellow may be chronic bronchitis, bronchiectasis, lung abscess and other diseases combined with bacterial infection. 1. Chronic bronchitis: under normal circumstances, chronic bronchitis is mucus white sputum, if the white mucus sputum changes to yellow, most of them are caused by bacterial infections, and yellow sputum or pus sputum will appear. 2. Bronchial dilatation: Bronchial dilatation is mostly secondary to respiratory infections, causing repeated inflammation of the bronchial tubes, which ultimately leads to the destruction of the bronchial tube walls. If acute infection occurs, yellow sputum or purulent sputum will be coughed up. 3. Lung abscess: The typical symptom of lung abscess is purulent sputum, and yellow sputum and bloody sputum may also occur. The main consideration is bacterial infection. Coughing up yellow sputum may also be seen in pneumonia and other diseases, it is recommended to go to the hospital to clarify the cause of the disease, under the guidance of the doctor for treatment.