The purpose of abdominal CT examination is to understand the abdominal organs; before the examination, the patient usually needs to drink an aqueous solution of intestinal contrast agent containing iodine, the purpose of which is to let the contrast agent fill the intestinal cavity in order to reduce the artifacts produced by the accumulation of gas in the intestinal cavity under the action of X-rays and avoid affecting the diagnostic effect due to artifacts; another purpose is: to facilitate the differential diagnosis of diseases after filling the intestine in order to improve the correct rate of diagnosis. Therefore, a process is needed after drinking the contrast agent, which takes a certain amount of time, and the abdominal CT examination can be performed after the contrast agent has reached the intestinal cavity of the area to be examined. However, not all abdominal CT exams require drinking intestinal contrast. When stones are considered, such as gallbladder stones, kidney stones, etc.; acute pancreatitis, intestinal obstruction, intestinal perforation, etc., it is usually not necessary to drink contrast, which is to prevent the contrast from masking the condition or aggravating it. And even at the same time, there is a sequence of patients drinking contrast. If you are conducting an upper abdominal examination, mainly to look at the liver, gallbladder, pancreas, spleen patients, drink 500 ml of aqueous solution of contrast agent first, and then drink 300 ml after half an hour will be ready for CT examination. And when you are looking at the kidneys, or even the bladder, prostate, uterus and other full abdominal CT exams, usually you can only perform the exam about 2 hours after drinking the contrast agent, and it is best to take a trip to the bathroom before the 1st drink of contrast agent to drain the urine, and then drink 1000 ml of contrast agent and 400 ml again before the exam, during which it is best not to go to the bathroom again and let the bladder fill up.