Bronchiectasis is not a disease, but a phenomenon of abnormal dilatation of bronchial structures caused by a variety of reasons, and therefore is not called a disease but a condition in medical science. This means that many diseases can be accompanied by bronchiectasis. The clinical manifestations are coughing, coughing up purulent sputum, hemoptysis and recurrent infections, and in severe cases, respiratory failure may occur. What is bronchiectasis? First, let’s take a look at the structure of the bronchi. The structure of a bronchus is like a big tree turned upside down. The main trunk of this tree is the main trachea, and then according to the dichotomy, one branch is divided into two branches, i.e. the left and right bronchi, and so on repeatedly through 26 branches, and finally connected to the alveoli. The relationship between the bronchi and the alveoli is like the relationship between the trunk, branches and leaves of a tree. Together with blood vessels and lymphatic vessels, they form the lungs. Bronchial dilatation is the abnormal expansion of the bronchial structure, that is, the bronchial thickening, deformation, some people may ask, the pipeline thickened, is not more usual? In fact, the thickening is accompanied by the destruction of autoimmune function. Simply put, the human body cannot expel the phlegm out of the body normally, and “running water does not rot, the household hub is not worm-eaten”, and the retained phlegm invites bacteria to multiply, which leads to repeated infections of bronchi and lungs. Subsequently, the blood vessels accompanying the bronchial tubes may be invaded and ruptured, leading to hemoptysis. The condition is further aggravated when a large amount of blood is not released in time to block the airways.