A colonoscopy is a common procedure that lets doctors examine the colon and rectum for abnormalities and changes. Sedated, the patient lies on his side on a table. The doctor inserts a flexible tube with tiny video camera at the tip into the rectum and colon, which is the large intestine. The test is takes about 30 minutes and is usually painless.
Your doctor may recommend a colonoscopy to:
- Screen for colon cancer or rectal cancer. Colorectal cancer is the third leading cause of cancer deaths in the United States. People age 50 and older are advised to have a colonoscopy every 10 years if they have no special risk factors for colon cancer. If a relative has had colon cancer, or if you have inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis, you may get a colonoscopy earlier or more often. If precancerous polyps are found, they can be removed during the colonoscopy.
- Check for the cause of intestinal symptoms. A colonoscopy may help your doctor diagnose the cause of abdominal pain, rectal bleeding, chronic constipation, chronic diarrhea and other problems.
Possible Complications of Colonoscopy
Colonoscopy is a safe and routine procedure. Still, like any procedure, it does carry some uncommon risks:
- Rarely, patients have an adverse reaction to the sedative used during the exam.
- There may be bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed. Bleeding typically stops on its own, but may require further treatments, including blood transfusions.
- The scope may cause a tear in the colon or rectum wall (perforation), which could require emergency surgery.
Preparation for a Colonoscopy
You will need to clean out your colon before the exam. Your doctor may ask you to consume only clear liquids the day before the exam, and take a laxative preparation. Your doctor may also ask you to stop taking certain medications one week in advance, especially if you take medications that contain iron, or take aspirin or other blood thinners.
During a Colonoscopy
You will be sedated with anesthesia given either by pill or IV infusion. You will lie on your side on the exam table, usually with your knees draw up toward your chest. The doctor will insert the scope into your rectum and up the entire length of your colon. Most colonoscopies last 20-30 minutes, and are followed by an hour in the recovery area.
After a Colonoscopy
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. You can eat normally, and should rest that day. 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. Call your doctor if you continue to pass blood or blood clots or if you have persistent abdominal pain or a fever of 100 F (37.8 C) or higher.
Colonoscopies are considered the “gold standard” for examination of the colon and rectum. However, sometimes polyps or other problems are not spotted. It’s important to take your bowel preparation as instructed to clean your colon effectively. This minimizes the risk that a problem will go unseen.
National Institutes of Health: Colonoscopy