Colonoscopy

Patient Information and "Risk" Form

Mr James Francombe, General and Colorectal Consultant Surgeon

To download the pdf version of this factsheet please click on this link

A colonoscopy is the most accurate way of examining the colon (otherwise known as the large bowel). It is both more sensitive and more specific than other types of bowel examination in that more subtle abnormalities can be identified and tissue specimens and/or polyps can be removed.

Preparation

For the procedure to be possible the bowel has to be cleaned out. You will receive a separate instruction sheet for bowel preparation. Please ensure that you read this carefully and if you have any doubts about the preparation please ask.

Sedation

In line with national current best practice we use light intravenous sedation for the procedure. This means that for many patients they are able to watch the procedure. If you experience discomfort during the examination it is imperative that you talk to the endoscopist and the nursing staff. In some circumstances it may be necessary for you to receive ore sedation and painkillers.

Risks

• As with any procedure, the benefits of colonoscopy are accompanied by a risk.

• Diagnostic Colonoscopy Pain/discomfort - most commonly due to the distension of the colon by air and transient stretching of the bowel wall.

• Incomplete examination - in approximately 1 in 10 procedures it may not be possible to see all of the colon. If this is the case the endoscopist will discuss with you whether or not you would need further tests.  

• Perforation - it is possible to inadvertently tear the large bowel lining and cause peritonitis. This may settle spontaneously but would usually require an operation to put it right. The risk of this happening is approximately 1 in 500 - 1 in 1000 examinations.

Figure 1. A flexible telescope will be passed along the full length of the colon.
Polypectomy If a polyp is found, it should be removed. Some polyps may turn into malignant cancer over a period of time and removing them when they are still benign eliminates this risk. A polyp is removed by burning its base with an electric current (figure 2).

Depending on the size of the polyp and how difficult it is to remove, there is a risk of causing either bleeding or making a hole in the wall of the bowel. The risk is approximately 1 in every 100 polyps removed.

• Bleeding from the polyp stalk - this may be evident at the time of the procedure or delayed up to 10-14 days after the examination. In the majority of circumstances bleeding usually settles of it own accord but medical attention should be sought if this occurs after you leave the hospital.
• Perforation - Bowel perforations usually require surgery. Should this happen, it has to be compared with the fact that, previously, everyone with a polyp large enough to cause concern would have had to undergo surgery.

Alternatives to colonoscopy.

• Barium enema
• Virtual colonography

These "X-ray" examinations still require the bowel to be cleared prior to the examination but they don't require any sedation. If abnormalities are identified by these techniques some patients may subsequently have to undergo colonoscopy to clarify the nature of the abnormality or remove any identified polyps.

After the procedure

You may feel distended with wind after the examination and that feeling will resolve as the wind passes. If you experience more severe pain it is imperative you seek medical advice.

Because the sedative drugs that we use have an amnesic effect at higher doses we recommend that patients should not drive or sign legal documents for 24 hours after the examination.

If any samples or polyps are removed at the time of the procedure you will be informed of any further results in due course.