Colonoscopy is a procedure to examine the lining of the colon (large intestine) with an instrument called an endoscope (or colonoscope). Usually the whole colon is examined (to the caecum) and sometimes also the end of the small intestine (terminal ileum). The aim of colonoscopy is to assess the colon for any diseases such as colitis (inflammation), Crohn’s disease, diverticulosis, polyps and tumours. Biopsies are often taken from the colon at the time of colonoscopy and polyps may be removed.

What are polyps and will they be removed?
Polyps are growths in the colon that are usually benign. If it is safe to do so they are usually removed at colonoscopy because they can, with time, enlarge and become cancerous. Removal of polyps will prevent their progression to colon cancer. When polyps are removed they are usually sent for examination by a pathologist. If the polyp is very large then your Gastroenterologist may decide not to remove it at the time because of excessive risk.  If this is the case then your Gastroenterologist will discuss it with you after the procedure and make arrangements for polyp removal.

How do I prepare?
For a successful procedure it is important that your Gastroenterologist can see the lining of your bowel clearly.  Bowel preparation takes place on the day before colonoscopy. This is explained on a separate sheet. (link to page) It is important to keep well hydrated (drink lots of fluid) while having the bowel preparation. You must stop all fluids 4 hours before your admission to the hospital.

Should I take my usual medications?
Some medications should be stopped up to a week before your procedure. Aspirin, Persantin, Asasantin and Clopidogrel (Iscover, Plavix or equivalent) will usually be stopped a week prior to the procedure and your Gastroenterologist may ask you to stay off these medications for a week afterwards if polyps are removed. However, in some patients your Gastroenterologist may decide to do the procedure on these medications, particularly if you have significant heart disease or recent insertion of coronary stents. Blood thinning (‘anti-coagulant’) drugs such as Warfarin, Xarelto and Pradaxa greatly increases the risk of bleeding and this needs to be discussed with your Gastroenterologist before the procedure. They will usually need to be stopped and you may need to have injections with Clexane (an injected anti-coagulant) around the time of the procedure.

Diabetics will need special consideration and this needs to be discussed with your Gastroenterologist before colonoscopy.  Most oral diabetic medications will be stopped on the morning of the procedure and insulin doses will be adjusted in the 24 hours before the procedure.  Iron tablets should be stopped a week before the procedure. Anti-inflammatory drugs should be stopped 48 hours before the procedure.

All other important medications can be taken normally.

What happens on the day?
When you arrive at the hospital the nursing staff will greet you and get you prepared for the procedure.  The anaesthetist will meet you and once you are in the procedure room you will have an intravenous cannula placed and be given a sedative.  The procedure is done with you asleep but it is not a general anaesthetic. You should recover quickly after the procedure.  Patients rarely have any memory of the procedure. 

Once you have been sedated your Gastroenterologist will perform the colonoscopy.  This usually takes approximately 30 minutes. Your Gastroenterologist will gently inflate the bowel with gas during the procedure.  Most of this gas will be removed by the end of the procedure but you may notice bloating and pass some residual gas after the procedure.

Are there any risks?
Colonoscopy is generally a low-risk procedure. However, it does carry a small risk of complications. One of the risks is perforation (tearing of the bowel). This can be caused by the instrument or at the time of polypectomy (polyp removal). Fortunately, it is a rare complication but it is serious and would require admission to hospital and often surgery, should it occur.

Bleeding can occur, particularly after polyp removal. Bleeding is more likely to occur if you have been on Aspirin or other blood thinning drugs. Bleeding usually stops spontaneously but may require intervention (eg surgery).

Intravenous sedation is generally safe and well tolerated but there is a small risk of allergic reaction to the drugs or aspiration (pneumonia from inhaling gastric contents while sedated).  Low blood pressure and oxygen levels can occur but you will be closely monitored during the procedure and this can usually be rapidly corrected.

The bowel preparation carries a risk of dehydration which can be associated with fainting and electrolyte disturbances. This is much less likely to happen if a good fluid intake is maintained while taking the bowel preparation. The bowel preparation is explained on a separate sheet.

No test is perfect. Colonoscopy is considered the most accurate way of assessing the colon but a lesion can be missed. The likelihood of missing something is greater if the bowel is not adequately cleaned out.

what happens after the procedure?
After the procedure you will be taken to the recovery room.  You may have bloating and abdominal cramping or discomfort but this usually settles quickly. Your Gastroenterologist will speak to you after the procedure to explain the findings but you may not recall all of the conversation.  You will be given a sheet with a summary of the findings to take home.  Your Gastroenterologist will send a written report to your GP and let you know whether or not they need to see you again.  If you need a repeat colonoscopy your Gastroenterologist will tell you when this should be. If biopsies have been taken or polyps have been removed your Gastroenterologist will usually write to you or talk to you a few days after the procedure.

You must not drive, return to work, drink alcohol, operate machinery, sign legal documents or use public transport unaccompanied until the following day. You should be escorted home by an adult and have someone with you at home until the following day.

Overall, colonoscopy is a low-risk procedure and should go without any major problems. If you have questions before the procedure please phone your Gastroenterologist.  If you have significant pain or bleeding the night after the procedure you can contact the hospital. In an emergency call 000.

Further information is available on the Gastroenterological Society of Australia website on the ‘consumer information’ page at