Doing CT may detect some of the intestinal diseases, such as tumors and intestinal obstruction. CT examination has the advantages of reconstruction, good reproducibility, fast examination speed, high density resolution, etc. It can observe the position, shape, lumen condition, and surrounding of intestinal wall lesions, etc. CT examination can be categorized into CT scanning, enhanced ct and so on. 1. CT scanning: it can show the shape and deformation of intestinal tube. It can detect intestinal obstruction, intussusception and other diseases through scanning. 2. Enhanced CT: it can make qualitative and quantitative analysis of the progress state of lesions, such as intestinal tumors. After oral administration of contrast agent, the deformation of intestinal wall can be seen more clearly, such as intestinal ulcers, stenosis, vascular lesions and other diseases. CT has poor diagnostic accuracy for diseases such as intestinal inflammation and polyps. Therefore, it is necessary to take into account the specific situation to determine whether to fast or not, and if there is a clear diagnosis, you must cooperate with the doctor for treatment.