The colonoscopy procedure and treatment
During a colonoscopy a thin flexible tube called a colonoscope is passed into the rectum (the back passage) and guided around the large bowel. The front end of the colonoscope carries a small camera with a light attached which allows the specialist to see the inside of the bowel on a television screen.
Andrea Giles, specialist screening practitioner, explains what happens during a colonoscopy.
The colonoscopy is an examination of the large bowel using a small flexible tube with a light and a camera inside. This is called a colonoscope. The colonoscope is passed into the bottom and gently manoeuvred around the bowel. During your colonoscopy we can see the lining of the bowel so that we are able to detect any abnormalities such as polyps or cancers which show on our TV screen. Your colonoscopy normally takes between 30 and 45 minutes to complete and is normally carried out under sedation.
Many of the people we interviewed had had a colonoscopy. Different hospitals have different instructions for patients. Some hospitals tell patients to stop drinking (as well as eating) a few hours before the procedure. Other hospitals allow patients to carry on drinking until it is done.
He was not to eat or drink anything on the morning of the colonoscopy, during which a polyp was...
People recalled how a nurse had met them at the hospital, checked their date of birth, took the blood pressure, and made them feel at ease. They were asked to change into a hospital gown, dressing gown and slippers. A doctor explained what would happen and asked them to sign a consent form.
His male nurse put him at ease before and during the colonoscopy; the doctor asked him to sign a...
My colonoscopy was scheduled for 2 o clock, I arrived at the hospital about 1.30 and sure enough around 2 o clock I was called into the day care room. I was met by a male nurse who was very pleasant, really pleasant. Made me feel at ease and told me what he wanted me to do which was to take my clothes off and I would put the cloak on that they provided and he would then give me a sedative, just a little prick in the back of my hand and then I would go through to the surgery room where I met the doctor who was very pleasant, very pleasant. The nurses made me feel really at ease, they were actually terrific. And I was asked different questions.
Did you sign a consent form?
I actually signed a consent form yes before I went through there and I was just asked, I was told about it, what they were going to do and I was very relaxed, they made me feel very relaxed. And they just inserted the camera and done their job and would, which I didn't know anything about, I didn't know a thing about what was'
You weren't awake enough to see the screen?
Oh I was, I was, I wake wide awake and I could see the screen and I had this nurse talking to me and they were doing their job which I didn't know nothing about.
You couldn't feel anything?
I couldn't feel a thing and they finished the job and everything was fine.
A colonoscopy is usually performed under sedation, but some people may choose not to be sedated.
Andrea Giles, specialist screening practitioner, explains 'sedation'.
Sedation is a medication that is administered directly into a vein. This will help you to feel relaxed and comfortable during your colonoscopy. Normally a combination of both a sedative and a painkilling injection is used, but this is not a general anaesthetic. Throughout your test a nurse will be looking after you and following your colonoscopy you will be asked to remain in the hospital until you have fully recovered, normally within one to three hours following your test. You will need to have a responsible adult to escort you home and to stay with you at home overnight.
Some people who had been sedated during their colonoscopy remembered little about it.
She was lightly sedated and asked questions during the colonoscopy but afterwards could not...
You don't remember.
I don't remember, no. And when I was taken, taken back to the room the consultant came in but I was asleep so I didn't speak to him. Then when I saw him the following week he said, 'Can you remember?' And I said, 'Oh I was asleep,' and he says, 'No you were asking me a lot of questions.' So I truthfully can't remember.
Doctors prefer patients to be lightly, rather than heavily sedated, so that patients can tell the doctor if they notice any pain. This helps to prevent serious complications.
The doctor wanted him relaxed but not too drowsy during the colonoscopy.
And he said, 'There are problems', and I should have said that even before I went in, I got undressed, the doctor had said to me, 'Look' he said, 'Ultimately, there is one in half a million chance we will say of bowel perforation, which is a serious condition' he said. He said, 'It rarely happens, of course' he said, ' But if you're awake and something doesn't feel quite right, you can tell me, and I can take steps to correct it, put it right.' Again all along the line there was so much reassurance.
Footnote' The colonoscope can cause a hole (a perforation) in the wall of the bowel. The chances of this happening are about one in 1, 500.
One man compared two colonoscopies, one he had had under sedation and the other without sedation. He thought it was better to be sedated:
He slept through his first colonoscopy and remembered nothing. He had a later colonoscopy without...
What sort of anaesthetic did you have, just a bit?
Just a local anaesthetic.
I think it's, delivered in the hand.
As a sedative or something?
I don't know but it certainly puts me to sleep.
I've since had another colonoscopy of which I didn't have anaesthetic and I have to say that it's not a comfortable thing if you're awake. It's not a comfortable thing but it's not painful. It's just that, it's not normal to me anyway. So I've experienced both with anaesthetic and without and I would prefer it with really, because you know, you're just not aware of what's going on.
Some people felt anxious before the colonoscopy but did not find it as uncomfortable as they expected. This man, who initially felt frightened, said that there was nothing to worry about.
Having a colonoscopy was easier than having a tooth out.
How were you feeling at that point?
Frightened, yeah frightened yeah. Yeah everything, there was lots of things going through my mind, what's going to happen now is, you know what's he going to do, is he going to put me to sleep and what's he going to do and what's he going to do. And then he, when he came in you know he was very nice, a very, very nice doctor, started talking to me about past history and one thing and another and he says, 'Turn on your left hand side,' after, oh he gave me the, he gave me the pethidine first into the hand, into the back of my hand and that's, that's all I felt really.
So the actual procedure isn't too uncomfortable then?
No, no there's nothing to worry about at all. You know it's, it's in the mind at first I think, you know it's, but it's, it is actually easier going, it's easier than going to the dentist and having a tooth out or a tooth filled, it's easier.
The colonoscopy was not as difficult as he expected it to be.
Well after sitting in the waiting room the doctor came to me and assured me of what was going to be done. I was slightly concerned as a human being which naturally anybody would be concerned about it ('). But fortunately the people who were there with me doing the job, they really made me comfortable. And at the moment, I had a West Indian young lady there who was by my head talking to me all the way through and the procedure, the operation was not as difficult as I thought it was. It was very smooth.
More than I expected it to be.
Were you given a little sedative to make you a little sleepy?
Yes I had [laughs], but somehow I stayed awake for it I think you know [laughs].
Another man, who chose to have a colonoscopy without sedation, said that the investigation was not a bad experience.
He had a colonoscopy without sedation because he wanted to know what was going on. He did not...
Yes I was given the choice of having a sedative. I chose not to have it, I'm always interested in things I suppose, I know an awful lot of people who haven't had the sedative but, but you needn't worry if you, if you want to be sedated they, they offer you that chance, that opportunity sorry.
And you said that you could see what was happening on the television screen, was it a special screen so you could see exactly what the doctors were seeing?
Yes in fact they encourage you to have, they tend to encourage you to have a look at it but to be perfectly frank with you, we're not experienced in that sort of field so to be honest I really didn't know what I was looking at. Trying to pick out, for example a polyp, I wouldn't have know if, if he found one or not. But it was just, it was just interesting to watch it. It also takes your mind off what they're doing.
And what does it actually feel like to have a colonoscopy?
No problem whatsoever, you don't feel anything.
It didn't feel uncomfortable?
It didn't feel uncomfortable at all, and that's without sedation.
However, a few people did remember having some pain or discomfort, either when the colonoscope moved round a corner in the bowel or when the doctor pumped air into the bowel to see the bowel wall more clearly. One man had a cramping pain at this stage.
He felt a cramp but this was relieved when the doctor withdrew some of the air from the bowel.
Some people were fascinated to see the inside of their bowel on the television screen. Many hadn't expected it to look so bright and clean and pink. However, one woman described the inside of her bowel as 'mostly yellow'. She said that the screen went 'red' when the polyps were removed. Only one man recalled seeing a 'dark thing' which the doctor said was 'a piece of poo'. Some people hadn't wanted to look at the screen, and a few found they couldn't see it from where they were lying in the room.
Her nurse stayed with her throughout the procedure. She liked seeing the inside of her bowel on...
Can you describe that?
Yes I just saw a probe and I asked certain questions like, 'What is that?' and you know 'what's happening there?' And they described to me exactly what was happening and you know really, and then I must have gone quiet because I know, the doctor said to the nurse, 'Has she gone to sleep?' [laughs]. She said, 'No she's watching the television screen, or the monitor,' so.
Did you see them removing the polyp?
Yes I did.
He found it interesting to watch the colonoscopy on the TV screen. He felt nothing as the...
Yes, the doctor said to me that if I watched, I think it was the bottom right I would see the instrument he used, appear. And I did and it, actually you could watch it go through your body. I was pretty much relaxed so I think I remember the beginning and more or less the end but I could see this, the instrument going through and I can remember at one point I asked what that was, I could see a dark thing and he just said, 'Don't worry about that, that's a piece of poo.' So [laugh] the laxative hadn't 100% worked but it was interested watching it, but as I say I can't remember everything about it, I was that relaxed.
So could you see the little camera whatever it is.
Yes that's the word I was thinking of, it's like a small instrument going through looking and you could see your insides basically.
And while that was happening did that hurt at all?
No I never felt, honestly I never felt a thing.
Oh that's good. And then?
I didn't even feel, to be honest when it went, when the put it in my back passage I never, I think, I can vaguely remember just feeling something but it didn't hurt.
During the colonoscopy the doctor may remove one or more polyps. Polyps are not cancer, but can sometimes change into cancer over a number of years. Polyps can be removed painlessly using a wire loop passed down the colonoscope tube. The polyp is cauterized. Sometimes a small tissue sample, called a biopsy, is taken. The tissue sample is checked in the laboratory for any abnormal cells that might indicate cancer.
He had six polyps removed from the bowel. One was potentially malignant. He was fascinated to see...
So did they remove all the polyps?
They removed all six but the final one, right at the top of the colon apparently, was the one which was giving the greatest concern and rather than being the kind that was on a, like a stalk, it was rather a flat structure, on the wall of the colon. They believe they've removed all that, and they believe that they have an almost 100% success rate, with those removals, but I have to go back in February next, that's three months' time for a further check just to ensure that everything is okay and thereon I will be on an annual check programme, if everything is okay.
During the colonoscopy could you see what was happening on the screen?
I did yes, it was rather intriguing, to watch one's inside in colour. I had no idea that it looked quite like that, and I was fascinated by the fact, as a photographer that things were so bright and so clear and so high definition on the screen and how clean the inside of the, the colon was. I didn't expect it to be quite so bright and so pink with the problems of the polyps so obvious.
And could you see them removing the polyp?
Yes I could, yes, but I couldn't feel anything internally. It did surprise me somewhat when I learnt that invasive techniques like this, when things were being removed from the wall of the colon, had no sense of feeling, because the internal area of the stomach there does not have the same sense of touch and pain as the external parts of the body. I didn't actually feel them being removed at all, I just watched them and it was quite fascinating.
It wasn't painful when the polyps were removed and he watched it all on the screen.
Well basically I go in, on the table, and you lie on your side facing the cameras, not the cameras the television like or whatever it's recorded on. And they're talking to you and the next thing is you're asleep, you know you go off in about minute and that's it. And then the next thing with me, the first time, whether being big they hadn't given me enough of it but I wake up and I can see this tube like and this camera going up and down and all sorts of things happening and it didn't strike me really, because I'm sort of half asleep what was going on. Then when they started talking about they'd found the cause of the problem which is these polyps hanging, they hang from the walls of the bowel then they're on about taking, you know and he said, 'Right we'll go up now, we'll get the lasso and go and do it,' you know. And I'm thinking how are they going to get a lasso to get up there you know because I'd got visions of Roy Rogers the cowboy. But you know then this lasso goes in, then they sort of clip it and they spray it and once they spray it the polyp stands up and they lasso it. Then they just say pull tight and they pull tight and I suppose, I don't know I've never asked him, it must burn it off. And then when they've done the three they then send like a basket, like an old flame in the wall of a castle, one of those type baskets which goes up, that opens out and grasp them out they come. And then it was a case of telling me what it had done. I said, 'Well I saw it all.' And he said, 'You're joking.' I said, 'No.'
Did it feel uncomfortable when they were doing that or was it alright?
Not at all, no. I think, as I say, the only time you feel any uncomfortableness is when they're really trying to come as high as they can into your bowels and I think when they come to the end that's the bit where you know you think blimey what's that? But there is no after effects whatsoever, none whatsoever and I don't think I've heard of anybody who's said they've had after effects.
The doctor removed two polyps during the colonoscopy. It wasn't painful.
Yes after I took my clothes off you know what I mean and they took me in on one of them trolleys, you know what I mean?
Yes you know lying down you know. And when I went in, I've been placed on a bed, you know there was two nurses and they were ever so nice you know. And then the doctor gave me this injection, you know help me to relax.
Make you sleepy?
Yes, I wasn't sleepy.
Relaxed, you know I can see everything you know that took place you know on the television, you know what I mean?
Could you see that?
What did you think of that?
Oh I said, 'Oh technology is great,' [laughs] I said, 'Technology is great,' you know. I could see me inside.
Did you like seeing inside?
Yes to be honest, to be honest, to be honest.
What could you see exactly?
Yeah all my, you know all my system, inside works you know yeah.
Good and what did they find?
They found what you call it, two.
Yeah two, two polyps.
Yeah which they removed yeah. They don't have to feel any pain. As I said I lie there and I can see you know because it's showing on the, on the television, you know the television, you know what I mean, I said, 'Technology is great,' you know it's good. You don't feel any pain or nothing, nothing, honestly I can say that.
One woman had three small polyps removed but the fourth was too big to remove during the colonoscopy. She had to have an operation (a right hemi-colectomy) at a later date to remove that one (see More treatment needed after an initial colonoscopy).
The doctor found four polyps in her bowel. Three were removed during the colonoscopy and she felt...
And they started from half a centimetre and they went up, and the biggest one was two and a half centimetres. And that one they had doubts with. They lasered the other three smaller ones and they found that they were alright. But they left the bigger one and said I needed an operation.
Because they didn't know how far to go into the bowel wall. So then I was booked in for an operation.
Although very few people found the colonoscopy painful, some said it was undignified or embarrassing (also see Why some were reluctant or did not take part).
Sometimes screening practitioners have to take special measures because the patient has another medical problem.
She was given antibiotics just before the colonoscopy because she had a leaking mitral valve in...
Last reviewed May 2016.