Colonoscopy

What is it?

For a colonoscopy to be effective the bowel must be clean to allow a good view of its surface.  An oral preparation needs to be taken 24 hours prior to the procedure which encourages the bowel to empty its contents.  The procedure is usually performed under sedation anaesthetic and requires a stay in hospital of only a few hours.  To minimise the risk from after-effects of the anaesthetic, patients should avoid driving for the next 24 hours.

Currently, colonoscopy is the best way to visulaise the entire colon and rectum and to allow both biopsies to be taken and polyps removed.  The major risk associated with a colonoscopy is perforation of the colon which, according to the National Health and Medical Research Council (NHMRC), has previoulsy been reported to occur in approximately one in every 1,000 colonoscopies in Australia.  This figure is NOT true when colonoiscopies are carried out by specialist and experienced colonoscopists and would be more accurately approximately one in every 10, 000 procedures.

Perforation may be treated with or without surgery, depending on the circumstances, but if surgery is required, then on occasions it is necessary to establish a colostomy, usually as a temporary measure.  Bleeding may occur after colonoscopy but this is rarely serious and will usually stop spontaneously.  Bleeding may require a repeat colonoscopy or surgery.  Both bleeding and perforation are more common if polyps are removed from the colon.  It is essential to remove polyps when they are found since some may ultimately become cancerous if left behind.

According to the NHMRC approximately one person in 10,000 will die following a colonoscopy, usually as a result of a perforation, and usually in patients with other significant medical problems.  The above explanation is not an exhaustive list of complications.  Naturally, you should consider these factors carefully before proceeding with the examination.  Again, most experienced specialists will have had zero (or close to zero) incidences of mortality in their practices.

Full details of the procedure and the risks involved will be detailed at your consultation with the doctor.  Please ask any questions you feel are required for your understanding of the procedure.

Screening Colonoscopy

The recommendations below reflect the work of a number of cancer organisations and other learned bodies, as outlined in the list of sources at the end of this document.  The recommendations are based on an assessment of the current state of knowledge and may vary according to the circumstances of any individual person.  The members of Sydney Colorectal Associates would be happy to discuss the implications of these recommendations and how they might be relevant to your own circumstances.

One male in seventeen will develop bowel cancer in Australia, and one female in twenty-three, and there is ample evidence that screening the community, as well as high risk groups can lead to a reduction in that incidence, by detecting and removing the polyps that lead to most bowel cancers.

Recommendations For Screening

People with:

• No risk factors for colorectal cancer,
• Second degree relatives with colorectal cancer,
• First degree relatives with polyps developing when older than sixty-five,
• A personal history of one or two small tubular adenomas or hyperplastic or metaplastic polyps,

should consider annual (optimally) faecal occult blood tests (or at least second yearly) and five-yearly sigmoidoscopy, or, alternatively, 5-10 yearly colonoscopy from the age of fifty.  There may be some justification for now recommending such screening commence at (around) age 45, given the increasing incidence of bowel cancers occurring in those under 50.

People with:

• A first degree relative greater with colorectal cancer when older than sixty five
• A first degree relative less than sixty with polyps

should consider colonoscopy every 5 years starting at the age of fifty, or ten years younger than the youngest age at which a relative was affected.

People with:

• A first degree relative with colorectal cancer when less than sixty-five

should consider colonoscopy every four years starting at the age of fifty, or ten years younger than the youngest age at which a relative was affected, and possibly at least by forty.

People with:

• A personal history of a polyp with a villous component,
• A personal history of a polyp, and a parent with colorectal cancer,
• First and second degree relatives with colorectal cancer,
• Two first degree relatives with colorectal cancer on the same side of the family,
• A personal history of a sessile serrated polyp especially from the right side of the colon

.should consider colonoscopy every 3 years

People with

• A history of colorectal cancer,
• A personal history of more than two large (more than 1cm) tubular adenomas,

should consider a colonoscopy every 2 years.

REFERENCES

• US Congress: Office of Technical Assessment: OTA-BO-H-146: April 1995. The Cost Effectiveness of Colorectal Cancer Screening in Average-Risk Adults.

• National Polyp Study. Colorectal Cancer Screening: Clinical Guidelines and Rationale. S.J. Winawer et al. Gastroenterology. 1997. Volume 112. Pages 594-642.

• Recommended Colorectal Cancer Surveillance Guidelines: American Society of Clinical Oncology – DESCHCE et al. J. Clinc Oncol. 1999. Volume 17. Pages 1312-1321.

• American Society of Colon and Rectal Surgeons. Practice Parameters for the Detection of Colorectal Neoplasms. Diseases of the Colon and Rectum. 1999. Volume 42. Pages 1123-1129.

• Guidelines for Colorectal Cancer Screening and Surveillance. American Society for Gastrointestinal Endoscopy. 2000. Volume 51. Pages 777-782.

• Cost Effectiveness Analysis of Colorectal Cancer Screening: A Systematic Review for the US Preventative Services Taskforce. M. Pignone et al. Ann Intern MED 2002. Volume 137. Pages 96-104.

• National Health and Medical Research Council. Clinical Practice Guidelines. The Prevention, Early Detection and Management of Colorectal Cancer. Draft. Revised 6th August, 2004.

• American Cancer Society Guidelines for the Early Detection of Cancer. R.A. Smith et al. CA Cancer J Clin. 2004. Volume 54. Pages 41-52