A 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 ed into the rectum. A tiny video camera at the tip of the tube allows the doctor to view the entire inside of the colon.
If necessary, polyps or other types of abnormal tissue can be removed through the endoscope during a colonoscopy. Tissue samples (biopsies) may be taken during a colonoscopy as well.
Why is this done
Your doctor may recommend a colonoscopy to
Look for any signs and symptoms of intestinal conditions. A colonoscopy can help your doctor explore possible causes of abdominal pain, rectal bleeding, chronic constipation, chronic diarrhea and other intestinal problems.
Screening for colon cancer. If you''re age 50 or older and have an average risk of colon cancer — and age is the only risk factor for colon cancer — your doctor may recommend a colonoscopy every 10 years or sometimes for a shorter period of time to screen for colon cancer. Colonoscopy is one option for colon cancer screening. Talk to your doctor about the options available.
Explore more polyps. If you''ve had polyps before, your doctor may recommend a follow-up colonoscopy to find and remove more polyps. This procedure is done to reduce the risk of colon cancer.
Risks
Colonoscopy poses few risks. Rarely, complications of a colonoscopy may include
Adverse reaction to the sedative used during the test
Bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed
A tear in the colon or rectal wall (perforation)
After discussing the risks of colonoscopy with you, your doctor will ask you to sign a consent form to authorize the procedure.
How to prepare
Before you have a colonoscopy, you will need to clean (empty) your colon. Any residue in your colon may obstruct 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. You will usually not be able to eat solid food the day before the test. Drinks may be limited to clear liquids — plain water, tea and coffee without milk or cream, meat broth and soda. Avoid red fluids, which can be confused with blood during a colonoscopy. You may not be able to eat or drink anything after midnight the night before the test.
Take a laxative. Your doctor will usually recommend a laxative in tablet or liquid form. You may be directed to take a laxative medicine the night before your colonoscopy, or you may be asked to take a laxative both the night before and the morning of your procedure.
Use an enema. In some cases, you may need to use an over-the-counter enema — either the night before the exam or a few hours before the exam — to empty your colon. This is generally only effective for emptying the lower colon and is not usually recommended as the primary method for emptying your colon.
Adjust your medications. Remind your doctor about 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 are taking aspirin or other blood-thinning medications, such as warfarin (Coumadin, Jantoven) newer anticoagulants such as dabigatran (Pradaxa) or rivaroxaban (Xarelto), which are used to reduce the risk of blood clots or stroke or heart medications that affect platelets, such as clopidogrel (Plavix).
You may need to adjust your dose or stop taking your medications temporarily.
What you can expect
during the procedure
During the colonoscopy, you''ll wear a pantyhose, and probably nothing else. Anesthesia is usually recommended. Sometimes a mild anesthetic is given in tablet form. In other cases, an anesthetic is given along with an intravenous pain reliever to reduce any discomfort.
The examination process begins with you lying on your side on an examination table, usually with your knees pressed toward your chest. The doctor s the colonoscope into the rectum.
An endoscope — which is long enough to reach anywhere in the colon — contains a spotlight and a tube (duct) that allows the doctor to pump air or carbon dioxide into the colon. The colon is inflated with air or carbon dioxide This allows the doctor a better view of the lining of the colon.
If the endoscope is moved or air is pumped, you may feel cramping or an urgent need to have a bowel movement.
The colonoscope also has a tiny camera at its tip. The camera sends images to an external monitor Which enables the doctor to examine the inside of the colon.
The doctor may also instruments through the channel to take samples of tissue (biopsies), or remove polyps or other foreign tissue.
A colonoscopy takes between 30 and 60 minutes.
After the procedure
It takes about an hour to start recovering from the anesthetic after the test. You will need someone to drive you home because it can take up to a day for the full effects of the drug to wear off. So, don''t drive, make any important decisions, or go back to work for the rest of the day.
If your doctor removed a polyp during a colonoscopy, he or she may advise you to temporarily follow a special diet.
You may feel bloated or pass gas for a few hours after the test due to the emptying of air in your colon. Walking may help relieve discomfort.
You may also notice a small amount of blood at your first stool after the test. Usually this does not cause any concern. Consult your doctor if you continue to have stools with blood or blood clots, or if you have persistent abdominal pain or fever. Although unlikely, it may happen immediately or in the first few days after the procedure, but it may be delayed for up to one to two weeks.
Results
Your doctor will review the results of your colonoscopy and then share them with you.
Negative result
A colonoscopy is considered negative if the doctor does not find any traces of a disorder in the colon.
Your doctor may also recommend another colonoscopy
In 10 years, if you have an average risk of colon cancer — you have no colon cancer risk factors other than age
Within five years, if you had a history of stomach polyps (polyps) during previous colonoscopy
Within one year, if you''ve had a residual colon condition that prevents your colon exam from being completed
Positive results
A colonoscopy is considered positive if the doctor finds any polyps or abnormal tissue in the colon.
Most polyps are not cancerous, but some can be precancerous. Polyps removed during a colonoscopy are sent to a lab for analysis to determine whether they are cancerous, precancerous or noncancerous.
Depending on the size and number of polyps, you may need to follow a stricter monitoring schedule in the future to look for more polyps.
If your doctor finds one or two polyps less than 0.4 inch (1 centimeter) in diameter, he or she may recommend a repeat colonoscopy in five to 10 years, depending on your risk factors for colon cancer.
Your doctor will recommend another colonoscopy sooner if you have
More than two polyps
Large polyp — larger than 0.4 inch (1 centimeter)
Polyps and also stool remaining in the colon that prevents a comprehensive examination of the colon
Distinctive cell polyps that indicate a higher risk of cancer in the future
precancerous polyps
If you have a polyp or other abnormal tissue that couldn''t be removed during a colonoscopy, your doctor may recommend a repeat exam by a gastroenterologist with particular expertise in removing large polyps, or a surgeon.
Problems with the test
If your doctor is concerned about the quality of the view through the endoscopy, he or she may recommend a repeat colonoscopy or shorten the recommended period for repeating this test. If the doctor can''t the scope through the entire colon, a barium enema or virtual colonoscopy may be best to check the rest of the colon.
