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. Some people experience a mild itching sensation. In very rare cases, a patient may become short of breath or experience swelling in the throat or other parts of the body. These can be indications of a more serious reaction to the contrast agent that should be treated promptly, so tell the technologist immediately if you experience these symptoms. Fortunately, with the safety of the newest contrast agents, these adverse effects are very rare.