I. Aspiration lung abscess Pathogenic inhalation through the mouth and nasopharyngeal cavity is the most important cause of lung abscess development. Purulent secretions such as tonsillitis, sinusitis, alveolar abscess or aging teeth; blood clots after oral, nasal and pharyngeal surgeries; tooth wax or vomit, etc., are inhaled into the lung through the trachea in cases of delirium and general anesthesia, causing fine bronchial obstruction, and pathogenic bacteria can multiply and cause disease. In addition, in some patients, no obvious cause is found, with 29.3% and 23% of cases reported in China and abroad, respectively. The disease may develop due to the influence of cold, extreme fatigue and other causative factors, the general immune status and the reduced defense function of the whistle tract, and the inhalation of contaminated secretions from the oral cavity during deep sleep. This type is often monogenic. Its occurrence is related to anatomical structure and body position. As the right common bronchus is more vain, and the diameter of the tube is thicker, inhalation secretions are easily inhaled into the right lung, so the onset of the right lung is more than the left lung medical education|editing.com. In the supine position, it is more likely to occur in the posterior segment of the upper lobe or the dorsal segment of the lower lobe; in the sitting position, it is more likely to occur in the posterior basal segment of the lower lobe. In the right lateral position, it is more likely to occur in the axillary subsegment formed by the anterior and posterior segments of the right upper lobe. Second, hematogenous lung abscesses Sepsis and sepsis due to skin trauma, infection, boils and carbuncles, osteomyelitis, postpartum pelvic infection, subacute bacterial endocarditis, etc. Pathogenic bacteria (mostly Staphylococcus aureus), septic emboli, are brought to the lung via the small circulation, causing small vessel embolism, inflammation and necrosis of lung tissue, and formation of abscesses. The lesions are often multiple, not necessarily distributed, and often occur in the marginal parts of both lungs. C. Secondary lung abscess Mostly secondary to other diseases, such as secondary infections of Staphylococcus aureus and Bacillus pneumoniae pneumonia, cavitary tuberculosis, bronchiectasis, bronchial cysts and bronchial carcinoma, which can cause lung abscess. Purulent lesions of adjacent organs of the lung or traumatic infections, subdiaphragmatic abscess, perinephric abscess, paracranial abscess, esophageal perforation, etc., can also form abscesses by penetrating into the lung. Fourth, amoebic lung abscess is mostly secondary to amoebic liver abscess. Since liver abscesses tend to occur at the top of the right lobe of the liver, it is easy to penetrate the diaphragm to the lower lobe of the right lung and form amoebic lung abscess.