Important information
Please read all of this leaflet or you may miss important information about your test. If you do not follow the instructions we may need to cancel your test on the day.
What is a colonoscopy?
A colonoscopy looks inside the large bowel (colon), the last part of the digestive system, with an endoscope. It is inserted into your bottom and moved around the whole of the large bowel by the endoscopist.
The procedure usually takes 20 to 30 minutes. You should expect to be in the department 2 to 4 hours. Unfortunately, it may not always be possible to run on time. The staff will try to keep you informed.
Why do I need a colonoscopy?
Your doctor has referred you to investigate your symptoms, such as a change in bowel habit (going to the toilet), bleeding, or anaemia. It may be a review of a pre-existing condition such as colitis or surveillance for polyps. It may help us find a cause for your symptoms and help to plan further treatment.
What else may be done during the procedure?
During some procedures we may take small biopsies (samples or remove polyps. Occasionally you may need to return for further treatment. You will be advised on the day.
What if I do not have the colonoscopy or change my mind?
It may be difficult to diagnose your condition or offer suitable treatment. You may find it helpful to discuss the test with your GP or referring doctor. If you decide not to go ahead, please let us know.
Can I seek a second opinion?
Yes, please seek advice from your GP or referring consultant.
Is there an alternative to colonoscopy?
A CT colonoscopy may show a cause for your symptoms however during a colonoscopy we are can also take biopsies and remove polyps.
What are the risks of a having a colonoscopy?
Complications are rare but it is important you are aware of them before the test.
Bleeding: may occur at the site of biopsy or polyp removal (risk of less than 1 in 1000 examinations where this is performed). This usually isn’t too serious and bleeding may stop on its own. If it does not it could be controlled by cauterization or injection treatment.
Perforation: (or tear in the bowel lining) the risk is around 1 in 10,000.
Reaction to medication: if you choose to have sedation, this may cause a problem with breathing, heart rate, or blood pressure. You will be monitored during the procedure to look out for this. Medication to reverse the sedation is available and we will support you as needed.
Missed diagnoses: there is a very small risk that the colonoscopy misses an abnormality due to small folds in the lining of the digestive tract. In these areas the views may be less clear.
Pain: most people can cope well with this procedure. It is common to experience discomfort for a short time, however, a small number of patients may have some pain.
Failure to complete the procedure: your comfort and safety are our priority, we will stop at any time if we cannot ensure his, or if there is a problem with equipment (this is rarer).
How do I prepare for the colonoscopy?
To allow clear views the colon must be clear and empty of waste material (poo). If not, the test may to be postponed or repeated.
The bowel preparation that has been prescribed works as a powerful laxative to clear your bowel. Please read the instructions carefully, follow any dietary instructions, and increase your intake of clear fluids (like water).
What about my medication?
You should take all your usual medication at the normal times with small sips of water unless you have been advised not to. Some medications need to be stopped or adjusted 1-2 weeks before your appointment.
Please notify the department as soon as possible if you:
- have diabetes
- take medication to thin your blood/prevent clotting like warfarin, apixaban, rivaroxaban, dabigatran, edoxaban, clopidogrel
- take long term steroids
- take iron tablets
- take weight loss injections
Why have I been asked if I have a pacemaker/internal cardiac defibrillator?
Implanted permanent pacemakers or cardiac defibrillators can be affected by electrical interference which may happen during colonoscopy. We can take precautions as long as you tell us before the procedure. Please notify the department if you have one.
Do I need to bring anything with me?
- A list of your medications and any you may need to take while you are in the department, such as insulin, inhalers, or GTN spray.
- A dressing gown and slippers, if you have them. You are advised not to bring valuables with you. Your belongings will stay with you throughout your stay.
What happens when I arrive on the Endoscopy unit?
Please speak to the receptionist. They will check your details and may ask you to complete a form with details of your medical history, and contact details of your next of kin and the person collecting you.
The admitting nurse will take you into a private room to ask questions about your general health, allergies, the results of the preparation you have taken. They will also measure your blood pressure, pulse, breathing rate, and oxygen levels. If you are diabetic your blood sugar will be measured by a fingerpick test, and if on warfarin your INR will be checked.
You will be asked to sign the consent form at this time either by the nurse or the endoscopist. If you have any questions or concerns, please let tell the nurse be aware.
You may be able to have a companion/carer with you at this time, but they will not be able to come with you into the procedure room.
Following this you will be asked to change into a gown and wait in a separate waiting area until the procedure room nurse comes to collect you. If you decide to have sedation, a cannula (flexible needle) will be inserted into a vein to allow intravenous sedation to be given.
This test is usually done with either Entonox - a gas you breathe in. Or you can have a sedative injection (midazolam) and an opiate painkiller injection (fentanyl). This is not a general anaesthetic, you will not be completely asleep, and you will be aware of your surroundings.
Sedation
If you decide to have sedation, a cannula (flexible needle) will be inserted into a vein to allow intravenous sedation to be given.
You will need a responsible adult to come to the unit to collect you, take you home, and care for you for at least 6 hours. For 24 hours after having sedation you cannot drive, operate machinery, drink alcohol, look after small children or vulnerable adults, or sign any legally binding documents. If you have not made these arrangements, we will not be able to offer sedation.
Entonox is a mixture of nitrous oxide and oxygen inhaled through a mouthpiece. It is an odourless, colourless gas which provides short term pain relief. If works quickly and wears off quickly. You can drive 30 minutes after having it.
If you have recently had any of the following Entonox may not be suitable: eye or ear surgery, a recent head, recent scuba diving activity, chronic breathing conditions such as emphysema or chronic obstructive pulmonary disease (COPD).
Who will be in the procedure room with me?
- A nurse who will monitor and support you.
- The endoscopist who will do the procedure.
- Another nurse who will assist the endoscopist.
The procedure will be done by a consultant or a non-medical/ clinical endoscopist. In some cases, another endoscopist who is doing further training (a qualified professional) may also be there. They will be learning to do colonoscopy under direct, expert supervision.
If you would prefer not to have your colonoscopy done by someone training, please let us know.
Student nurses may also be there and be supervised by the training nursing staff.
What can I expect during the colonoscopy?
- Once in the procedure room you will be introduced to the team and they will ask you some questions. The Endoscopist will have a short conversation with you.
- You will lie on your left side on the trolley and be given the sedation or Entonox.
- A short internal rectal examination is done before inserting the scope.
- You will be monitored and cared for by your nurse throughout the procedure.
- Once the procedure is complete you are taken, on the trolley, into the recovery area. You will continue to be monitored until you feel able to get up and dressed. Refreshments are available.
- The person collecting you will be contacted.
- You will be given discharge advice and paperwork, and details of any further tests needed.
- We will give you contact numbers in case you have issues once you go home.
Will I be in a mixed ward?
There are separate male/female waiting and recovery areas.
What should I do when I get home?
If you have had sedation please remember, you must not drink alcohol, drive, operate machinery, care for vulnerable adults or small children, or signing any legally binding documents.
You can eat and drink normally.
What if I feel unwell or have any concerns after I have been discharged?
If you have any of the following please contact your GP, NHS 111, or go to the Emergency Department and take your results with you:
- a fever
- passing a lot of blood from your bottom or black stools (poo)
- severe abdominal pain
- severe bloating or vomiting
A copy of your results is sent to your GP. You will also be given a copy in case you need to seek medical advice before your GP receives their copy.
If you have any communication or mobility difficulties, or any concerns about your test please contact the Endoscopy Helpline. Leave your name, number and a short message: 0117 414 5077.
Date published: 5 March 2026 Review due: 31 March 2029 PI number: BFT002231