Colonoscopy is a procedure that uses a thin, flexible camera to check for abnormalities or disease in your lower intestine or colon.
The colon is the lowest portion of the gastrointestinal tract—the series of organs that takes in food, absorbs nutrients, and disposes of waste. The colon is attached to the anus, the opening in your body where feces are expelled.
A colonoscopy can be done as a pre-emptive screening for colon cancer and other problems. The screening can help doctors:
- look for signs of cancers and other problems
- explore the cause of unexplained changes in bowel habits
- evaluate symptoms of pain or bleeding located in the abdominal area
- find a reason for weight loss, chronic constipation, or diarrhea
The U.S. Preventive Services Task Force (USPSTF) recommends screening for colorectal cancer. Fecal occult blood testing, sigmoidoscopy, or colonoscopy is used to test adults from ages 50 to 75. According to the American College of Surgeons, everyone over the age of 50 who is at average risk of colon cancer should get a colonoscopy once every 10 years. If your risk is higher, you may need more frequent procedures. Between 76 and 90 percent of colon cancer can be prevented through colonoscopies (American College of Surgeons).
Since a colonoscopy is a routine procedure, there are typically few lasting effects from this test. The benefits of detecting problems and beginning treatment far outweigh the risks of complications from a colonoscopy.
However, some rare complications include:
- bleeding from a biopsy site, if a biopsy is done
- reaction to the sedative
- tear in the rectal wall or colon
Your doctor will give you complete instructions for your “bowel prep,” which sounds much more traumatic than it actually is. Basically, it means you must have a clear liquid diet for 24 to 72 hours prior to your procedure. The typical bowel prep diet includes:
- bouillon or broth
- plain coffee or tea
- pulp-free juice
- sports drinks, such as Gatorade
Make sure not to drink any liquids containing red or purple dye, as they may discolor your colon. That means if you’re drinking sports drinks, the red and purple flavors are off-limits.
Inform your doctor of any medications—including over-the-counter drugs or supplements—you are taking. Some may affect your colonoscopy, and if so, your doctor may tell you to stop taking them. These might include blood thinners, vitamins that contain iron, and certain diabetes medications.
Your doctor will give you a laxative to take the night before your appointment. He or she may also advise you to use an enema at the same time, or the day of the procedure.
You may want to arrange for a ride home after your appointment. You’ll want the sedative to fully wear off before getting behind the wheel.
Just before your colonoscopy, you’ll change into a hospital gown. Most people receive some type of sedative, usually in pill form.
While you’re seated and sedated, your doctor will guide a flexible, lighted tube called a colonoscope into your anus. Slowly and gently, he or she will guide it up through the rectum and into the colon. A camera on the end of the colonoscope transmits images to a monitor that your doctor will be watching.
Once the scope is positioned, your doctor will inflate your colon using carbon dioxide gas. This gives him or her a better view.
Depending on what your doctor finds—or what he or she suspects prior to the test— your doctor may remove polyps or a tissue sample for biopsy during this procedure. You’ll be awake during your colonoscopy, so your doctor will be able to tell you what is happening.
The entire procedure takes about 30 minutes to an hour.
After the procedure is done, you’ll wait for about an hour to allow the sedative wear off. You’ll be advised not to drive for the next 24 hours, until its full effects fade.
In addition, you’ll also typically experience some gas and bloating from the gas your doctor blew into your colon. Give this time to get out of your system. If it continues for days after, it could be signaling a problem and you should contact your doctor.
Also, a little bit of blood in your stool after the procedure is normal. However, if you continue to pass blood or blood clots, experience abdominal pain, or have a fever over 100°F, call your doctor.
If your doctor removed tissue or a polyp during a biopsy, it will be sent to a laboratory for testing. Your doctor will inform you of the results when they are ready, normally within a few days.