Colonoscopy

What it is

A flexible camera is passed through the anus around the whole large intestine to the caecum and often into the last part of the small intestine. Polyps found on the way are removed, which prevents them growing into cancer; this is why screening colonoscopy reduces bowel cancer deaths.

Why it is done

• A positive stool screening test (FIT) or bleeding from the bowel
• Change in bowel habit, unexplained weight loss or iron-deficiency anaemia
• Diagnosing and monitoring inflammatory bowel disease
• Surveillance after polyps or bowel cancer, and in high-risk families
• Removing polyps, stopping bleeding, dilating strictures, decompressing a twisted bowel

Before the procedure

• Low-fibre diet for a few days, then strong laxative bowel preparation the day before, drinking litres of clear fluid until the output runs clear
• Iron tablets stopped a week before; blood thinners and diabetes medicines adjusted
• Sedation and painkiller through a cannula, or gas and air

Step by step

1. Lying on the left side; the lubricated scope is inserted and advanced with carbon dioxide inflating the bowel
2. The scope is steered around the sigmoid, descending, transverse and ascending colon to the caecum, changing position or with abdominal pressure to straighten loops
3. The lining is inspected carefully on the slow withdrawal (at least six minutes)
4. Polyps are snared with a wire loop and cut with diathermy, or removed cold if small; larger lesions lifted and resected in pieces
5. Biopsies are taken from any abnormal or inflamed areas

Afterwards

• Wind and cramps for a few hours as gas passes
• Eat and drink normally; a little blood after polypectomy is expected
• No driving for 24 hours after sedation
• Histology in one to two weeks decides surveillance intervals

Recovery

Normal activities the next day.