Colonoscopy

What is a colonoscopy?

A colonoscopy is a procedure where a camera is passed through the anus to the very start of the large bowel (caecum). If necessary the very last part of the small bowel (terminal ileum) is also examined. The lining of the bowel (mucosa) is carefully examined for abnormalities such as inflammation, diverticular disease, polyps and cancer.

A colonoscopy is the most sensitive test for detecting bowel cancer or polyps.

The colonoscope is a tube roughly 2cm in diameter that distends the colon with air so that the entire wall of the bowel can be inspected. For a colonoscopy to be an effective test, the bowel must be free from any faecal matter so as not to hide any small polyps, hence the necessity of bowel preparation 24 hours before the procedure.

Does it hurt?

A colonoscopy is a painless procedure. An anaethetist will put you to sleep, so that you will be monitored and comfortable for the entire procedure. You will not feel any pain from any biopsy sites on the inside of the bowel. You may feel ‘gassy’ or bloated after the colonoscopy, and feel like you need to pass flatus (gas).

What is a polypectomy?

A polypectomy is the process of removing a polyp found within the bowel. Polyps can be either benign, pre-malignant or malignant, and in most situations it is difficult to tell just by looking at them. For this reason, almost all polyps are either removed or destroyed if found.

Depending on the size and the location of the polyp it may be biopsied and destroyed, removed completely or just biopsied. The specimen is then sent to the pathologist to get histological results.

Typically a polypectomy is either done with forceps or a snare (lasso) that is passed through the colonoscope. Electrical current travels down the forceps to coagulate or burn the small blood vessels in the wall of the bowel so as to prevent bleeding from the polypectomy site. The electrical current may also be used to destroy any abnormal tissue or blood vessels.

Most (>90%) of polyps can be managed via the colonoscope.

What is tatooing?

Tattooing is a the process of placing a permanent dye in the wall of the bowel as a means of identifying a specific location or abnormality. This is especially important for laparoscopic bowel resections or resections following complete removal of a polyp. The dye is completely inert and causes no problems by remaining in the bowel wall.

How long does it take?

A colonoscopy typically takes  30 minutes to perform. The majority are performed as day procedures. In some instances you may be admitted the day before to help prevent the associated dehydration that accompanies the bowel preparation.

Is it safe?

A colonoscopy is one of the most common procedures performed. It is very safe, but, like all medical procedures, has its own risks.

If a polypectomy is performed the risk of bleeding is low; roughly 1 in a 1000.

This risk is increased markedly if you are taking anticoagulation or anti-platelet medication, and your surgeon should be aware of this. If you are unable to cease your anticoagulation medication for other medical reasons, your surgeon may decide not to perform a polypectomy or biopsy until it is safe to.

The risk of a bowel perforation is the most serious complication that can occur following colonoscopy. Its incidence is roughly 1 in 600 colonoscopies. It can occur due to a number of different risk factors

  • Scar tissue from previous surgery or inflammation
  • Narrowing of the sigmoid due to diverticular disease
  • Previous radiotherapy
  • Unusually long colon (looping)