Brief Description – Colonoscopy is a procedure that lets your doctor look inside your entire large intestine. It uses an instrument called a colonoscope, which has a tiny camera attached to a long, thin tube.
Why the Test is Performed
Colonoscopy is done to:
- Look for early signs of cancer in the colon and rectum
- Routinely screen for colorectal cancer, which usually starts at age 50
- Check for the cause of blood in the stool or rectal bleeding.
- Check for the cause of dark or black stools.
- Check for the cause of chronic diarrhoea.
- Check for the cause of iron deficiency anaemia.
- Check for the cause of sudden, unexplained weight loss.
- Check the colon after abnormal results from a CT scan, MRI, stool test, or barium enema.
- Watch or treat inflammatory bowel disease (IBD).
- Check for the cause of long-term, unexplained belly pain.How the Test is Performed
- Colonoscopy may be done in a doctor’s office, clinic, or a hospital. The test is most often done by a doctor who works with problems of the digestive system (gastroenterologist).
- You will be given a gown to wear during the test. You may lie on your left side with your knees pulled up to your belly.
- The doctor will insert a thin, flexible colonoscope in your anus and move it slowly through the rectum and into your colon.
- Air will be used to inflate your colon so the doctor can look at the lining of the colon through the scope or on a computer screen hooked to the scope.
- The doctor will look at the whole length of your colon as the scope is gently moved in and then out of your colon. The doctor may also use tiny tools, such as forceps, loops, or swabs, through the scope to collect tissue samples (biopsy) or take out growths.
Usually, people do not feel anything if a biopsy is done or if polyps are taken out.
The scope is slowly pulled out of your anus and the air escapes. Your anal area will be cleaned with tissues.
The test usually takes 30 to 45 minutes, but it may take longer, depending upon what is found and what is done during the test.
How to Prepare For the Test
- Before this test, you will need to clean out your colon (colon prep). Colon prep takes 1 to 2 days, depending on which type of prep your doctor recommends. Some preps may be taken the evening before the test. For many people, the prep is worse than the test.
- The bowel prep may be uncomfortable, and you may feel hungry on the clear liquid diet.
- Plan to stay home during your prep time since you will need to use the bathroom often.
- The colon prep causes loose, frequent stools and diarrhoea so that your colon will be empty for the test.
- If you need to drink a special solution as part of your prep, be sure to have clear fruit juices or soft drinks to drink after the prep because the solution may have a salty or unpleasant taste.
- You may be asked to stop taking aspirin or iron supplements 7 to 14 days before the test. If you take blood-thinning medicines regularly, discuss with your doctor how to manage your medicine.
- You will be asked to sign a consent form that says you understand the risks of the test and agree to have it done.
- Arrange to have someone take you home after the test, because you may be given a medicine (sedative) to help you relax before the test.During the Test
During the test, you may feel very sleepy and relaxed from the sedative and pain medicines. You may feel the need to have a bowel movement while the scope is in your colon. You may also feel some cramping.
Breathe deeply and slowly through your mouth to relax your belly muscles. You will likely feel and hear some air escape around the scope. There is no need to be embarrassed about it. The passing of air is expected. You may be asked to change your position during the test. If you are having pain, tell your doctor.
After the Test
After the test, you may need to stay at the clinic for 1 to 2 hours. Or you may be allowed to leave sooner with the person who will be driving you home.
Your doctor will tell you when you can eat your normal diet and do your normal activities. Drink a lot of fluid after the test to replace the fluids you may have lost during the colon prep, but do not drink alcohol.
If you are having cramps, passing gas may help relieve them. If you received a sedative during the test, do not drive, operate machinery, or sign legal documents for 24 hours after the test. If a biopsy was done or a polyp taken out, you may have traces of blood in your stool for a few days.
There is a small chance for problems from a colonoscopy. The scope or a small tool may tear the lining of the colon causing pain or bleeding.