Sometimes it is necessary for the doctor to introduce air into the colon to improve visibility. Before having a colonoscopy the colon must be clear of stool so that the doctor has good visibility. The patient must undergo a preparation that may include a liquid diet, enema, and laxatives to clear stool from the colon. The technique for bowel preparation may differ by health facility. A sedative is given before a person undergoes colonoscopy.
Many people sleep through the whole procedure and feel little or no discomfort.
Occasionally, the insertion of air during the procedure may cause the same kind of discomfort as gas pain. A barium enema is a radiological examination of the rectum and the entire colon. Before a barium enema, the patient may have to undergo a preparation that includes a liquid diet, enema, or laxative to clear stool from the colon. This preparation may differ from exam to exam and from one doctor to another. This contrast material outlines the colon.