Before performing a pelvic CT examination, it is important to carefully check the CT examination request form to understand the condition and clarify the purpose and requirements of the examination. For the application form with unclear examination purpose requirements, it should be confirmed with the clinician. For enhanced scanners, they should be prepared according to the requirements for the use of iodine-containing contrast agent, fasting for 4 hours before the examination, taking 1000-1500 ml of 1%-2% aqueous iodine-containing contrast agent orally in divided doses for 6-10 hours before the examination, so as to make the distal and proximal segments of the small intestine as well as the colon fill up, and drinking a lot of water before the scanning in order to keep the bladder filled up. Female married patients need to place a vaginal plug, there are rectal or sigmoid colon invasion, can be injected directly into the rectum 1%-2% iodine-containing contrast solution or air 300 ml. barium can not be used to perform gastrointestinal examination, so as to avoid artifacts formed by the residual contrast agent in the intestines after the examination, which will affect the quality of the image and lead to misdiagnosis.