A CT examination usually takes from fifteen minutes to half an hour. When the exam is over, the patient may be asked to wait until the images are examined to determine if more images are needed. CT scanning causes no pain, and with spiral CT, the need to lie still for any length of time is reduced. For different parts of the body, the patient preparation will be different. You may be asked to swallow a liquid contrast agent that allows the radiologist to better see the stomach, small bowel, and colon.
Some patients find the taste mildly unpleasant, but most can easily tolerate it.
Your exam may require the administration of the agent by enema if the colon is the focus of the study. You will experience a sense of abdominal fullness and may feel an increasing need to expel the liquid. Commonly, a contrast agent is injected into a vein to better define the blood vessels and kidneys , and to accentuate the appearance between normal and abnormal tissue in organs like the liver and spleen . Some people report feeling a flush of heat and sometimes a metallic taste in the back of the mouth. These sensations usually disappear within a minute or two.