Colonoscopy

Colonoscopy is performed to investigate symptoms such as bleeding from the bowel, a persistent change in bowel habit, unexplained abdominal pain, iron-deficiency anaemia or unexplained weight loss. It is also the follow-up test when a bowel cancer screening test (faecal occult blood test) returns a positive result.

It is used for surveillance in people at increased risk of bowel cancer, including those with a strong family history, a previous history of polyps or bowel cancer, or long-standing inflammatory bowel disease. During the procedure, polyps can be removed and small tissue samples (biopsies) taken. Removing polyps prevents them from developing into cancer over time, which is why colonoscopy is both a diagnostic and a preventive procedure. It is also used before and after bowel cancer surgery to examine the rest of the colon.

For the bowel lining to be seen clearly, the colon must be completely empty. You will be given a bowel preparation kit and written instructions. In the days beforehand you will be asked to follow a low-fibre diet, and on the day before the procedure to have clear fluids only while drinking the preparation solution, which causes frequent loose bowel motions. Staying well hydrated with clear fluids is important.

You will need to fast from food for six hours before the procedure, with clear fluids usually permitted until two hours beforehand. Please tell us about all your medications, especially blood thinners, iron tablets and diabetes medication, as some need to be stopped or adjusted. If you have kidney or heart problems, let us know, as the type of preparation may need to be changed.

Colonoscopy is performed as a day procedure under sedation given by an anaesthetist, so you will be comfortable and most people have no memory of it. Once you are asleep, the colonoscope, a thin flexible tube with a camera and light at its tip, is passed through the anus and gently advanced around the whole large bowel to the point where it joins the small bowel. Air or carbon dioxide is used to inflate the bowel so the lining can be inspected carefully.

Any polyps found are usually removed during the same procedure using a small wire loop or forceps passed through the scope, and biopsies are taken of any abnormal areas. The procedure typically takes 20 to 40 minutes. Serious complications such as bleeding or a perforation of the bowel wall are uncommon, and your surgeon will discuss the risks with you beforehand.

You will rest in the recovery area until the sedation has worn off, usually within an hour or two, and can then go home with a responsible adult. Because of the sedation, you must not drive, operate machinery, drink alcohol or sign legal documents for 24 hours. Mild bloating or wind is common as the air passes and settles within a few hours, and you can usually eat and drink normally straight away.

The preliminary findings are discussed with you on the day and a written report is sent to your referring doctor. If polyps were removed or biopsies taken, the pathology results take about a week and are reviewed with you at a follow-up appointment, along with a recommendation on when your next colonoscopy should be. Contact your surgeon or the hospital if you develop significant abdominal pain, ongoing bleeding or fever after the procedure.