When colonoscopy is advised
- Bleeding from the back passage, at any age (it's not always "just piles")
- A change in bowel habit lasting more than 3–4 weeks
- Iron-deficiency anaemia or unexplained weight loss
- Long-standing diarrhoea, or suspected inflammatory bowel disease
- Screening, especially with a family history of bowel cancer or polyps
Bowel preparation: the part people worry about
A clean bowel is what makes the test accurate. A few tips that make it easier:
- Low-fibre diet for 1–2 days before
- Split dosing: half the prep the evening before, half on the morning of the test
- Drink it chilled, through a straw, with clear fluids in between
More on preparing for your procedure.
During the test
With sedation, most people are comfortable and drowsy. It usually takes 20–40 minutes. Air or CO₂ is used to open the bowel, so some bloating afterwards is normal.
Risks
Colonoscopy is safe for most people. In published studies, a tear (perforation) occurs in roughly 1 in 1,000–3,000 diagnostic procedures, and bleeding is uncommon; both are a little more likely when large polyps are removed. For people who need the test, missing a cancer is the bigger risk.
Common questions
Is a stool test or blood test as good as colonoscopy?
Stool tests (like FIT) are useful screening tools but miss many polyps, and a positive result still needs colonoscopy. Colonoscopy can both find and remove polyps.
Can I go to work the same day?
Not after sedation. Rest for the day; most people are back to normal the next day.