Ask anyone who has had a colonoscopy what they remember most, and many will surprise you: it is usually the preparation the day before, not the examination itself. The test itself is straightforward once you know the order of events, so here they are, step by step.

The short video at the top of this page is a helpful preview. In just over three minutes it describes a colonoscopy — a flexible fibre-optic examination of the colon — and shows the view the doctor works from, so the steps below will already look familiar when your own appointment comes around. Doctors suggest this test to look for the source of symptoms such as bleeding, persistent abdominal pain, or a lasting change in bowel habit, to check on growths called polyps, and as a screening test for colorectal cancer in people whose doctor recommends it.

Step 1: Clearing the stage the day before

A camera can only show what it can see, and the colon has to be empty for that. So the day before, you'll follow the preparation instructions from your clinic: usually a period of clear fluids only, plus a preparation solution that empties the bowel. It means staying close to a bathroom, and it isn't glamorous — but it is the part that decides whether the examination works well, so it is worth doing properly. If anything in the instructions is unclear, ask beforehand rather than guessing.

Step 2: Arriving, and settling in

On the day, you'll change into a gown and lie on your side on an examination couch. Most people are given sedation through a small tube in a vein, which makes you sleepy and relaxed — some people doze through the whole thing and remember very little afterwards. Tell the team beforehand about any medicines you take and any allergies you have; they will ask, but it helps to have the list ready.

Step 3: The examination itself

The doctor gently passes the colonoscope — a thin, flexible tube with a camera and a light at its tip — through the rectum and around the colon, following its curves. A little air is puffed in to open the folds so the lining can be seen clearly, which can cause a feeling of pressure or bloating. On the screen, the doctor inspects the lining as the scope is slowly withdrawn. This is also the moment when the test can turn into treatment: small polyps can usually be removed there and then through the scope, and tiny tissue samples (biopsies) can be taken for the laboratory — neither of which you would feel. If you'd like a second look at what a healthy examination looks like on screen, the site also carries a short video of a normal colonoscopy from the same channel.

Step 4: Waking up and hearing the results

Afterwards you rest while the sedation wears off, and someone will need to take you home — you shouldn't drive yourself. Trapped air can leave you bloated for a while, and passing it is both expected and encouraged. The doctor will usually tell you the headline findings the same day; if samples were sent to the laboratory, those results follow later, and your clinic will explain how you'll receive them. Most people are back to eating normally the same day and back to routine the next. Severe abdominal pain, heavy bleeding, or fever afterwards aren't part of normal recovery — contact your care team promptly if they occur. And if all this talk of abdominal procedures has you curious about the surgical side of the same specialty, our guide to appendectomy and appendix removal explains another common one in the same plain terms.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician, researcher, and former Duke faculty.

Frequently Asked Questions

Does a colonoscopy hurt?
It is usually done with sedation, so most people feel little more than pressure or bloating from the air used during the examination, and many remember very little of it afterwards. Tell the team if you are uncomfortable — they can adjust things.

How long does a colonoscopy take?
The examination itself is usually well under an hour. You will be at the unit longer than that, though, because of check-in, the sedation, and recovery time afterwards.

Can polyps really be removed during the same test?
Yes. Small polyps can often be removed through the colonoscope during the examination, and small tissue samples can be taken for testing. You wouldn't feel either happening.

Why do I need someone to take me home?
Because of the sedation. It can leave you drowsy and slow your reactions for the rest of the day, so driving yourself — and making big decisions — should wait until the following day.

Educational only — this article is general information about colonoscopy, not medical advice. Whether and when you should have this test is a decision for you and your own doctor.