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The colon is the last portion of the digestive tract. It is a hollow tube about 1.5 metres long that ends at the rectum and anus. The main function of the colon is to store unabsorbed food before it is eliminated in the faeces. A colonoscopy is a medical procedure that examines the large bowel. The colonoscope is the device used to perform a colonoscopy. This device consists of a long, firm and flexible plastic tube with a tiny video camera and light at one end. The gastroenterologist carefully guides this instrument in various directions to look inside the colon. The picture from the camera appears on a television monitor to provide a clear, magnified view of the colon lining.
Conditions that may be diagnosed with colonoscopy
A colonoscopy can be used to look for cancer of the colon (bowel cancer) or colon polyps, which are growths on the lining of the colon that can sometimes be cancerous or may grow to be cancerous. A colonoscopy may be performed in order to find the cause of signs and symptoms including:
- Bleeding from the rectum
- Blood in the stools
- Pus or mucus in the stools
- Unexplained abdominal pain
- Changes in bowel habits such as unexplained and long-lasting diarrhoea
Medical issues to consider
Before the procedure, you need to discuss a range of issues with your doctor including:
- All medications (prescription and non-prescription), vitamins, minerals and herbal supplements you are currently taking.
- The bowel must be clean so that the doctor can see the colon lining. This cleaning process varies, but you may be told to modify your diet and avoid certain foods in the week before the procedure.
- You will be given a 'bowel preparation kit' and instructions on how to use it. The kit contains substances that help cleanse the bowel. It may also include liquid preparations that are designed to stimulate bowel movements as well as laxative tablets and other preparations. It is vital that you strictly follow the instructions given to you by medical staff.
- You will be advised not to consume any foods or liquids, other than the liquids provided in the bowel preparation kit, in the eight to 10 hours before the procedure.
Colonoscopy procedure
Before the colonoscopy procedure, an intravenous line is inserted into the back of your hand to provide medications that make you relaxed and drowsy. Although you will probably be 'awake' during the procedure, the medications usually prevent you from having any memories of it.
Colonoscopy is usually performed on a table. The patient lies on their left-hand side with their knees tucked up to their chest. The colonoscope is gently inserted through the anus and up into the colon, and air is introduced to help the colonoscope pass. Once the colonoscope has reached the point where the colon joins the small intestine, the doctor slowly withdraws it while looking carefully at the colon lining. Photographs may be taken. The procedure generally takes 15 minutes to one hour.
If colon polyps are found during a colonoscopy, they are removed and the tissue is sent for analysis to determine if the polyp is cancerous. Polyp removal or biopsy may cause excessive bleeding, which may require blood transfusion or re-insertion of the colonoscope to control the bleeding.
Immediately after the procedure
After the procedure, you can expect:
- Bloating
- Gas
- Mild cramping
- You may be offered a drink and something light to eat about one hour after you are fully awake
- Usually, you can go home after four hours or so.
Possible complications
Colonoscopy is a safe procedure, although complications sometimes occur. These include:
- Excessive bleeding
- Perforation or puncture of the colon wall
Taking care of yourself at home
Be advised by your doctor, but general suggestions include:
- Patients should not drive themselves home after a colonoscopy procedure, due to the effects of the medications that are given.
- Don't consume alcohol, as it may interact with the medications.
- Follow all dietary suggestions.
Long term outlook
Any abdominal bloating, pain and flatulence will resolve within a couple of days. These symptoms are caused by the air that is pumped into the colon during the procedure. You will need to see your doctor again to discuss your results from the colonoscopy. Treatment depends on the diagnosis.
Other tests
There are alternative tests to colonoscopy, but they aren't always appropriate. Sometimes, these tests are done in conjunction with colonoscopy, because of the extra information they provide. These tests can include:
- Barium enema - a specialised x-ray of the colon, using a contrasting dye flushed into the body via the anus.
- CT scan - a special contrasting dye is swallowed, then pictures are taken of the digestive tract.
- Sigmoidoscopy - a similar procedure to the colonoscopy, except the sigmoidoscope is much shorter. The device can't access past the sigmoid colon, which is the section of bowel that joins directly to the rectum.
Where to get help
- Your doctor
- Gastroenterologist
Things to remember
- A colonoscopy is a medical procedure that examines the large bowel.
- The colonoscope consists of a long, firm and flexible plastic tube with a tiny video camera and light at one end.
- A colonoscopy can be used to look for cancer of the entire colon (bowel cancer) or colon polyps, and to help diagnose symptoms such as unexplained diarrhoea, abdominal pain or blood in the stool. Early cancers and polyps can be removed at the same time.
You might also be interested in:
Bowel cancer.
Collagenous colitis.
Crohn's and colitis.
Endometriosis - treatment options.
Endoscopy.
Irritable bowel syndrome.
MRI scan.
Want to know more?
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