Colonoscopy is an examination used to detect changes or abnormalities in the large intestine (colon) and rectum.
During a colonoscopy, a long, flexible tube (colonoscope) is inserted into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the inside of the entire colon.
If necessary, polyps or other types of abnormal tissue can be removed through the scope during a colonoscopy. Tissue samples (biopsies) can be taken during a colonoscopy as well.
Your doctor may recommend a colonoscopy to:
Before a colonoscopy, you'll need to clean out (empty) your colon. Any residue in your colon may obscure the view of your colon and rectum during the exam.
During a colonoscopy, you'll wear a gown, but likely nothing else. Sedation is usually recommended. Sometimes a mild sedative is given in pill form. In other cases, the sedative is combined with an intravenous pain medication to minimize any discomfort.
You'll begin the exam lying on your side on the exam table, usually with your knees drawn toward your chest. The doctor will insert a colonoscope into your rectum.
The scope — which is long enough to reach the entire length of your colon — contains a light and a tube (channel) that allows the doctor to pump air or carbon dioxide into your colon. The air or carbon dioxide inflates the colon, which provides a better view of the lining of the colon.
When the scope is moved or air is introduced, you may feel abdominal cramping or the urge to have a bowel movement.
The colonoscope also contains a tiny video camera at its tip. The camera sends images to an external monitor so that the doctor can study the inside of your colon.
The doctor can also insert instruments through the channel to take tissue samples (biopsies) or remove polyps or other areas of abnormal tissue.
A colonoscopy typically takes about 30 to 60 minutes.
After the exam, it takes about an hour to begin to recover from the sedative. You'll need someone to take you home because it can take up to a day for the full effects of the sedative to wear off. Don't drive or make important decisions or go back to work for the rest of the day.
If your doctor removed a polyp during your colonoscopy, you may be advised to eat a special diet temporarily.
You may feel bloated or pass gas for a few hours after the exam, as you clear the air from your colon. Walking may help relieve any discomfort.
You may also notice a small amount of blood with your first bowel movement after the exam. Usually this isn't cause for alarm. Consult your doctor if you continue to pass blood or blood clots or if you have persistent abdominal pain or a fever. While unlikely, this may occur immediately or in the first few days after the procedure, but may be delayed for up to one to two weeks.