Preparation for CT examination of small intestine: 1 day before CT examination: fasting of crumbly food and oral laxative for 1 day (the purpose is to empty the intestinal tract of feces so as not to treat the feces in the intestinal lumen as a lesion). You can always drink water and apply sports drinks to replenish calories and electrolytes. On the day of CT examination: take oral intestinal contrast agent (20ml of pantethine + 1000ml-1500ml of purified water), 2-3 hours before CT examination, and finish it orally within half an hour; after 2-3 hours of oral intestinal contrast agent, perform whole abdominal plain CT examination. Note: 1. This method is prohibited for patients suspected of having intestinal obstruction; 2. To avoid hypoglycemia after fasting, patients can always drink sugar water or sports drinks before CT examination; if patients cannot eat, intravenous rehydration therapy is required.