What is a colonoscopy?
A colonoscopy examines the whole large intestine (colon) and the end of the small intestine using a flexible camera. It is the most accurate test for finding the cause of bleeding from the back passage, persistent change in bowel habit and unexplained anaemia — and it allows polyps to be removed during the same procedure, before they can turn into cancer.
When is it recommended?
- Blood in the stool or black stools
- Diarrhoea or constipation lasting more than a few weeks
- Unexplained weight loss or iron-deficiency anaemia
- Suspected ulcerative colitis or Crohn’s disease
- Family history of colon cancer, or screening from age 45–50
Bowel preparation matters
A clean bowel is the single most important factor for a good colonoscopy. You will receive a written, day-by-day preparation plan. See our patient guide to colonoscopy preparation.
What to expect
-
1
2–3 days before
Low-fibre diet as advised.
-
2
Day before
Clear liquids and the bowel-cleansing solution as prescribed.
-
3
The procedure
Usually 20–40 minutes under sedation.
-
4
After
Mild bloating is common. Do not drive for the rest of the day.
Conditions this helps with
Frequently asked questions
Medically reviewed by Dr. Shivam Kalia MBBS, MD (Medicine), DM (Gastroenterology) · Consultant Gastroenterologist & Hepatologist