The purpose of performing abdominal CT examination is to find out whether there are infectious diseases in the abdominal organs, such as inflammation, tuberculosis, abscess, etc.; whether there are occupancies, such as benign and malignant tumors, metastatic tumors, etc.; whether there are deformities, stones, obstructions, perforations, fluid accumulation, etc. Before the examination, the patient usually needs to drink 2% aqueous solution containing iodine contrast agent. One of its purposes is: to let the contrast agent fill the whole intestinal cavity to reduce the artifacts produced by the accumulation of gas in the intestinal cavity under the action of X-ray, so as to avoid affecting the diagnostic effect due to artifacts; the other is: to facilitate the differential diagnosis of diseases after filling the intestine, so as to improve the correct rate of diagnosis. Therefore, after drinking the contrast agent, a process is needed, and CT examination can be performed after the contrast agent drunk reaches the intestinal cavity of the site to be examined. And why are some patients ready for abdominal CT examination as soon as they come in? When stones are considered, such as: gallbladder stones, kidney stones, etc.; acute pancreatitis, intestinal obstruction, intestinal perforation usually do not need to drink contrast agent, this is to prevent contrast agent from masking the condition or aggravating it. Even if the patients drink contrast agent at the same time, there is also a sequence, if the upper abdominal examination, mainly to see the liver, gallbladder, pancreas, spleen patients, first drink 500 ml of contrast agent water solution, and then drink 300 ml after half an hour can be CT examination. While looking at the kidneys, or even the bladder, prostate, uterus and other whole abdominal CT examinations, usually only about 2 hours after drinking the contrast agent, and it is best to take a trip to the bathroom before the first drink of contrast agent to drain the urine, and then drink 1000 ml of contrast agent, and then drink 400 ml before the examination, during which it is best not to go to the bathroom again to let the bladder fill up. Patients who have just had a barium meal examination of the gastrointestinal tract, which is commonly referred to as a barium meal angiogram of the digestive tract, need a delay of 1 week after a full abdominal examination with sex CT. The contrast agent used in a barium gastrointestinal study is denser than that used in a CT study and can produce artifacts in response to X-rays, similar in nature to the artifacts due to gas described earlier. Therefore, these two examinations are often in conflict. When doing a barium meal examination of the gastrointestinal tract, it is necessary to fast and not eat or drink, so as to facilitate the barium to be adequately coated on the gastric and intestinal mucosa and to see the gastric and intestinal mucosa clearly. In contrast, abdominal CT examination requires drinking a large amount of contrast solution, which is very different from each other. Therefore, one of the two must be examined, not both.