CT urine holding is usually meant to be performed for the examination of the urinary system and pelvic organs. After holding the urine, the bladder can be filled, so that the internal condition of the organ to be examined can be better observed, and there is no presence of lesions. Other than that, such as head CT, lung CT, abdominal organs, bones, joints and other parts of the examination is not required to hold urine. Therefore, before the CT examination, the doctor must inform the patient of the parts to be examined and the matters to be noted during the examination, including whether it is necessary to have an empty stomach and whether it is necessary to hold urine, and at the same time, it is necessary to remove the metal objects before the examination, so as not to affect the results of the examination.