It is possible that yellow sputum with blood in it is caused by the following factors: 1. trachea and bronchitis caused by bacterial infections in the trachea and bronchus, and when patients cough violently, the mucous membrane of the respiratory tract will be damaged, resulting in the symptoms of blood in sputum. 2. yellow sputum with blood in it for a long time may also be caused by pulmonary tuberculosis, and in addition to yellow sputum with blood in it, it will also be accompanied by symptoms such as low fever and wasting. 3. 3.Symptoms caused by bronchopulmonary cancer and other diseases, such as hoarseness, in addition to blood in the sputum. Clinically, there are many factors that lead to the appearance of yellow sputum with blood in the sputum, so it is recommended to go to the hospital for lung CT and other examinations to further clarify the cause and treatment.