There are four examination methods for lung abscess as follows: 1. Chest X-ray is the main diagnostic method for lung abscess. As the abscess has the characteristic of spreading to different lobes, it can spread to multiple lobes or even the whole lung. However, if it occurs at the beginning at a site other than those mentioned above, special etiology should be suspected, such as tumor occlusive abscess or lung cyst infection. Pulmonary abscesses have a wide range of pathological changes and very different x-rays in the different stages. In the acute stage (within 1 week), it is a large dense and modulated shadow, distributed in a wedge shape according to the lobar segments, with the tip toward the lung door and the lateral side close to the thorax, mediastinum or interlobular pleural surface; under treatment, the shadow changes more rapidly. When the abscess communicates with the bronchus, a cavity appears, and due to the fact that the draining bronchus is mostly incompetent and the postural factors, the pus cannot be completely drained, and fluid planes are common on the film. Because of the thick wall and still surrounding inflammation, there is a thick layer outside the cavity, cloudy inflammatory infiltrative shadow, and fibrosis around the chronic ones. The cavity varies in size and shape and can be round, oval or irregular, and many are multifocal. After treatment, if it improves, the cavity gradually shrinks and disappears, leaving a fibrous striated shadow and pleural hypertrophy shadow. 2.CT examination can better understand the scope, location and cavity of the lesion. A few abscesses in which pus is not discharged show round block shadow, but there are small cavities within the visible, not many of them are really solid blocks, which can be easily mistaken for tumors. Pulmonary volume reduction is evident in fibrosis, and complete bronchial occlusion may be present with pulmonary atelectasis. Interlobular pleural thickening may be seen. If the abscess breaks into the chest cavity to form a pus or pneumothorax, there are corresponding changes on the film. 3, fiberoptic bronchoscopy Fiberoptic bronchoscopy is best performed when the patient is more stable, not in high fever and severe inflammation of the whistle. The purpose of the examination: ① Excluding foreign bodies and tumors in the bronchus, if there are foreign bodies can be removed, suspected tumors biopsy and brush film. ②To understand the situation in the bronchus, generally it can be seen that the bronchus is congested, edema, inflammatory or scar stenosis, which can facilitate further decision of treatment. ③ To understand the source of pus and to clarify the site of the lesion, while aspirating pus, injecting bronchodilators and antibiotics, etc. This therapeutic examination can be performed once a week. It is also better to put a thin catheter into the pus cavity through the bronchial biopsy hole to aspirate pus and inject drugs. If the bacteriological diagnosis is unclear or tuberculosis cannot be excluded, the bronchial secretion can be taken from the deep part of the bronchus to check the tuberculosis bacteria and general bacteriological culture and drug sensitivity test. 4.Bronchography
The bronchial changes in lung abscess are quite obvious, and bronchography can understand the location and scope of lesions, and discover lesions that are not seen on plain film or are not clear on tomography, which is helpful to determine the principle of treatment and surgical methods. It can reveal dilated bronchi, filled pus cavities, distorted bronchi, stenosis and bronchopleural fistula. Pulmonary abscesses are characterized by “three more” features that can be seen in the imaging, namely: (i) multi-room pus cavities, connected by irregular sinus tracts; (ii) multi-branch drainage, i.e. one pus cavity with more than one bronchial drainage; and (iii) multi-lobe invasion. The contrast is best done when there is no hemoptysis and little sputum, and if necessary, the contrast is injected after the sputum is aspirated through the fibrinoscope, which fills better, and the contrast can also be aspirated after the film is taken.