What is colonoscopy?
This procedure involves a colonoscope(a thin flexible tube with a camera at the tip) being passed through the anus into the large intestine (colon). It allows the doctor to inspect the large intestine for any abnormalities and also perform specialised procedures such as biopsies and removal of polyps.
Why should I have a colonoscopy?
Colonoscopy is useful both for the diagnosis and treatment of different bowel conditions. It can help doctors diagnose unexplained changes in bowel habits, abdominal pain, bleeding from the bowel and weight loss. Patients who have tested positive for blood on stool test (+ve FOB Test), must undergo a colonoscopy to rule out colorectal cancer. Colonoscopy also allows your doctor to remove polyps (small growths in the colon), which if left untreated, can turn sinister. Patients with a history of such polyps, will need to have repeat colonoscopy in due course.
How do I prepare for a colonoscopy?
For a successful colonoscopy, it is essential to empty the bowels thoroughly of all waste material, which can be done by taking a bowel preparation. Failure to do this prior to colonoscopy may mean the doctor won’t be able to examine the large intestine thoroughly, and you may have to return for a repeat procedure.
Please see Bowel Preparation Information sheet for instructions.
How is colonoscopy performed?
Before the procedure a light anaesthetic is given. You will not receive a full general anaesthetic. You may be slightly aware of what is going on in the room, but generally you won’t remember anything. A highly qualified anaesthetist and nursing staff will monitor your vital signs during the procedure and will attempt to make you as comfortable as possible.
Examination of the bowel
Once sedated and lying in a comfortable position on your left side, the doctor inserts the colonoscope (‘scope’) through the anus and slowly guides it into the colon. A small camera at the end of the scope transmits a video image to a monitor, allowing the doctor to carefully examine the intestinal lining. Once the scope has reached the other end of the large bowel, it is slowly withdrawn and the lining of the bowel is carefully examined again.
Removal of polyps and biopsy
A polyp is a small tissue growth attached to the bowel wall. These are common in adults and are usually benign. Most colorectal cancer however begins as a polyp. Some polyps never become cancerous however It is impossible to predict which polyps will progress to cancer and which will remain as benign polyps. For this reason it is advised that all polyps be removed at the time of colonoscopy using tiny tools passed through the scope as removing them early is an effective way to prevent cancer. If you have any queries or reservations about removing polyps, please inform the staff before the procedure. If Large polyps are removed then small metal clips may be placed to reduce the risk of bleeding. Small tissue samples or biopsies of the bowel may also be taken for examination. This allows the doctor to review it with a microscope for signs of disease.
What happens after colonoscopy?
Following the procedure you will remain in the recovery area for an hour or two until the sedation medication wears off. You will usually be given something light to eat and drink once you are awake. When you wake up you may feel a little bloated. This is due to the air that was inserted during the procedure, and will pass over the next hour or so.
Your doctor will briefly inform you of your test results on the day of the procedure. A follow-up appointment may be made to discuss the test results more fully. The results of any biopsies or samples taken will take a few days.
Because of the sedation given during the procedure, it is very important that you do not drive a car, travel on public transport alone, operate machinery, sign legal documents or drink alcohol on the same day after the test. It is strongly advised that a friend or relative take you home and stay with you.
What are the risks or side-effects?
Although complications can occur, they are rare when the procedure is performed by doctors who are specially trained in colonoscopy. In Australia, very few people experience serious side-effects from colonoscopy and polypectomy (polyp removal). The chance of complications depends on the exact type of procedure that is being performed and other factors including your general health.
Depending on the reason for the procedure, there may be risks of NOT having the procedure e.g. missed disease or delayed diagnosis. These risks may be fatal, e.g. delayed diagnosis of cancer.
Common risks of the procedure include:
- Mild abdominal pain, bloating and discomfort due to gas used during the procedure (usually settles with walking)
- Nausea and vomiting.
- Faintness or dizziness, especially when you start to move around.
- Headache.
- Pain, redness or bruising at the sedation injection site (usually in the hand or arm).
- Muscle aches and pains.
- Allergy to medications given at time of the procedure.
- Minor rectal bleeding (one in 100) if a biopsy has been taken or polyp removed.
Occasionally, people may be intolerant to the bowel preparation medication and experience headaches or vomiting. In a few cases, if the colonoscopy is not successfully completed it may need to be repeated.
Very rarely (one in 1,000 cases), the bowel lining may be torn or splenic injury may happen, and if this occurs you will be admitted to hospital and surgery may be required to repair it.
Colonoscopy is considered to provide the most accurate assessment of the colon. However, no test is perfect and there is a risk that an abnormality may not be detected. A colonoscopy can miss lesions in the bowel in 2% – 8% of cases. For serious lesions such as cancer, the chance is much less, but still present.
If you have severe abdominal pain, persistent bleeding from anus, fever or any other symptoms that may concern you hours or days after the colonoscopy you should contact the hospital or your doctor’s rooms immediately using details as above.
