Hospital and Clinic
The truth about colonoscopy
Keeping you comfortable during a colonoscopy
Are you preparing for a colonoscopy? Are you contemplating whether now is the right time for you to have this important screening? Or, are you nervous, confused and hoping for some straight answers? Regardless of where you’re at in the process, you’ve come to the right place.
The information below will help you better understand colonoscopies and colon cancer. Our experts are here to ensure your experience is comfortable and you’re well-prepared.
What is a colonoscopy?
A colonoscopy (koe-lun-OS-kuh-pee) is an exam 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.
Why get a colonoscopy?
Your doctor may recommend a colonoscopy to:
- Investigate intestinal signs and symptoms. A colonoscopy can help your doctor explore possible causes of abdominal pain, rectal bleeding, chronic constipation, chronic diarrhea and other intestinal problems.
- Screen for colon cancer. If you're age 50 or older and at average risk of colon cancer — you have no colon cancer risk factors other than age — your doctor may recommend a colonoscopy every 10 years or sometimes sooner to screen for colon cancer. Colonoscopy is one option for colon cancer screening. Talk with your doctor about your options.
- Look for more polyps. If you have had polyps before, your doctor may recommend a follow-up colonoscopy to look for and remove any additional polyps. This is done to reduce your risk of colon cancer.
When should I get a colonoscopy?Experts recommend starting colon screening in patients at the age of 50 or 10 years prior to the age at which an immediate family member was diagnosed. For example, if your mother was diagnosed at age 48, have your first screening at age 38. The ideal time for African Americans or Native Americans/Alaska Natives to have their first colon cancer screening is 45 years old.
What's the colonoscopy process?
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.
To empty your colon, your doctor may ask you to:
- Follow a special diet the day before the exam. Typically, you won't be able to eat solid food the day before the exam. Drinks may be limited to clear liquids — plain water, tea and coffee without milk or cream, broth, and carbonated beverages. Avoid red liquids, which can be confused with blood during the colonoscopy. You may not be able to eat or drink anything after midnight the night before the exam.
- Take a laxative. Your doctor may suggest taking a laxative, in either pill form or liquid form. You may be instructed to take the laxative the night before your colonoscopy, or you may be asked to use the laxative both the night before and the morning of the procedure.
- Use an enema kit. In some cases, you may need to use an over-the-counter enema kit — either the night before the exam or a few hours before the exam — to empty your colon.
- Adjust your medications. Remind your doctor of your medications at least a week before the exam — especially if you have diabetes, high blood pressure or heart problems or if you take medications or supplements that contain iron.
Also tell your doctor if you take aspirin or other medications that thin the blood, such as warfarin (Coumadin); newer anticoagulants, such as dabigatran (Pradaxa) or rivaroxaban (Xarelto), used to reduce risk of blot clots or stroke; or clopidogrel (Plavix).
You may need to adjust your dosages or stop taking the medications temporarily.
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 into your colon. The air 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 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 20 minutes to an hour.
After the exam
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 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 of 100 F (37.8 C) or higher.
Is a colonoscopy my only option?An alternative to a traditional colonoscopy is a new at-home test, which Mayo Clinic helped develop, that utilizes a stool sample to test for cancer DNA. Talk to your health care provider to see if this may be an option for you.
What is colorectal cancer?
Colorectal cancer is an umbrella term used for cancer of the large intestine (colon), which is the lower part of your digestive system, and rectal cancer, which occurs in the last several inches of your colon.
In addition to regular screenings, healthy lifestyle improvements may help prevent colorectal cancer. Exercise most days of the week; eat a diet rich in fruits, vegetables and whole grains; quit smoking; maintain a healthy weight; and drink alcohol in moderation, if at all.