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Having a colonoscopy

Read our guide below to understand what to expect from a colonoscopy.

You can also download a PDF version of this patient information by following the link on the right.

You’ve been advised by your GP or hospital doctor to have an investigation known as a colonoscopy. Read all the information below and follow the instructions carefully – failure to do so may result in your test being cancelled.

If you need to change your appointment

If the date or time isn’t convenient, call the Endoscopy department on 01296 831210 so we can reschedule your appointment.

Consent

All procedures done in hospital need your consent. This is a legal requirement.

Read this information carefully. It will help you to make an informed choice and understand the risks and benefits associated with your procedure.

Admission to hospital

During the admission stage, one of the endoscopy specialist nurses will explain your procedure and go through the reasons for the procedure and any risks associated. You’ll have the opportunity to ask questions. Once you’re completely happy, we’ll ask you to sign a consent form. Please note you have the right to withdraw your consent at any time.

What happens to my written consent?

Your signed consent is held in our hospital notes. If you want a copy, we can organise one for your personal records.

Tissue samples

For some procedures, we take tissue samples for microscopic examination. Instead of destroying the samples after this examination, we ask your permission to use these tissue samples for teaching and research purposes. We treat all specimens anonymously.

If you need a translator

If you don’t speak English, an independent translator should be available to make sure you understand the test. We prefer this to a member of your family or friend translating for you.

If we can’t get proper consent, we’ll cancel the procedure.

What is a colonoscopy?

It’s an examination using a flexible, telescopic tube to look accurately at the lining of your entire large bowel(colon). The long tube, called a colonoscope, is inserted at your anus and manoeuvred around to the far end of your large bowel (the caecum).

The colonoscope has an illumination channel. This allows light to be directed onto the lining of your bowel, which relays pictures back to a screen. It allows the endoscopist to have a clear view and to check whether your bowel is abnormal.

Why do I need to have a colonoscopy?

Your symptoms may suggest that you have a problem with the large bowel which needs investigation.

You may also need a colonoscopy because you:

  • are having the procedure as part of the bowel cancer screening programme
  • have previously had surgery for bowel cancer – a regular colonoscopy will check for signs of any recurrence.
  • have from inflammatory bowel disease
  • have previously had polyps removed
  • have a family history of bowel cancer.

What are the benefits of having a colonoscopy?

If there’s any abnormality in the bowel, a colonoscopy will show this. It’s a relatively quick procedure lasting approximately 20 to 30 minutes.

You won’t need a general anaesthetic but may need a short acting sedative drug while the procedure is being carried out. It allows the endoscopist to take samples (biopsies) of tissue so they can be examined under a microscope. Polyps if found may also be removed at the same time.

What are polyps?

A polyp is a protrusion from the lining of the bowel. Some polyps are on a stalk and some are flat and attached directly onto the bowel lining. Polyps when found are generally removed or sampled (biopsied) at the same time as they may grow and cause problems.

A polyp may be removed in one of two ways. For large polyps a snare (a wire loop) is placed around the polyp, and a high frequency current may then be applied to remove the polyp. Smaller polyps are removed by biopsy forceps (forceps that cut).

Is there an alternative to having a colonoscopy?

There are alternatives such as a CT scan which is an x-ray procedure, but it doesn’t allow the doctor to take samples. You may have already had one of these investigations which didn’t pick up the problem or showed an abnormality.

Are there any risks involved?

A colonoscopy is a skilled procedure performed by a trained endoscopist who takes every care to reduce any risks. However, as it’s an invasive procedure it carries the risk of complications. Although these complications happen very rarely, we must make you aware of them.

Perforation or tear of the lining in the bowel

This is a rare complication. Around 1 in every 1,000 procedures need hospital admission for observation and possible surgery to repair the perforation. The risk of perforation is higher with polyp removal (around 1 in every 100 procedures).

Bleeding at the site of polyp removal or biopsy

Bleeding is normally minor and usually stops on its own. If it doesn’t, it may need controlling by cauterisation, clipping or injection treatment. The risk of bleeding is higher with polyp removal (around 1 in every 30 procedures).

Risk of a missed lesion

Although this has been chosen as the best test to diagnose your symptoms, no test is perfect. There is a risk of 4 in a 100 that we might miss a large polyp or other important finding during your test.

Risks associated with having sedation

Sedation in a small number of patients may cause problems with slower breathing, low blood pressure and a slow heart rate. Careful monitoring of these vital signs during the procedure by your nurse will detect any changes early. These can be treated rapidly.

Incomplete procedure

In a small number of patients the colonoscope can’t be manoeuvred all the way around the colon. You may then need to have a CT scan.

Will I need to be sedated?

Most colonoscopies are done under sedation. Sedation is given through an intravenous cannula (small plastic tube put into your vein). It’s a sedative, not an anaesthetic, and will make most people feel drowsy and relaxed. Some patients may like to use entonox (gas and air) as an inhaled pain killer.

How long will I have to be at the hospital?

You’ll usually have the colonoscopy as a day patient, involving a stay of between 2 to 4 hours. The Endoscopy Unit closes at 6pm. Appointment times are not exact. The unit has to respond to unexpected emergencies and therefore occasional delays are inevitable.

Preparing for the examination

Your bowel must be completely clear of all waste matter. This happens by using a bowel cleansing medicine. The medicine forces diarrhoea so it’s advisable to stay at home during this time as you need to be close to a toilet. The medicine works quickly and so you won’t be able to work whilst taking the medicine.

IT’S EXTREMELY IMPORTANT THAT YOU FOLLOW THE INSTRUCTIONS CAREFULLY

If you have a colostomy the medicine will work in the same way to clear your bowel. You’re advised to put on a special drainable appliance (pouch) before taking the medicine until after the examination. If you don’t have any drainable appliances, contact your stoma care nurse who will advise you and provide a suitable appliance.

Preparing for your colonoscopy

Please bring a dressing gown and slippers. We’ll ask you to change into a hospital gown for the procedure.

Do not bring valuable items such as credit cards and jewellery.

If you’re asthmatic Bring your inhalers with you and tell the nurse.

If you have diabetes Tell the Endoscopy unit. Bring your diabetic tablets and/or insulin with you on the day. If you need advice, contact your diabetes specialist nurse.

If you have sleep apnoea Bring your usual breathing apparatus with you for use during the procedure.

If you’re taking iron tablets Stop taking them 7 days before the test.

If you’re taking Warfarin or any other blood thinning tablets, tell the Endoscopy team when making your appointment.

Other blood thinning tablets include:

  • Rivoroxaban
  • Dabigatran
  • Apixaban
  • Edoxaban
  • Clopidogrel
  • other ‘antiplatelet’ drugs.

You can continue taking Aspirin.

If you have a heart valve replacement, epilepsy, are pregnant, trying to conceive or breastfeeding, are in poor health or very frail, call us.

If you suffer from kidney failure, you must contact us for advice.

Is there anything else I need to bring?

Yes. Please bring a list of your medication with you.

What happens when I arrive?

The receptionist will book you in and a member of the Endoscopy nursing team will collect you from the reception area. If you haven’t already been seen for a pre-assessment discussion, we’ll take you to a private room to get a brief medical history and document your current medications.
The nurse will explain the risks involved in the procedure. You’ll have the opportunity to ask questions. You can also sign your consent form if you haven’t already done so.

Family friends and relatives

After the pre-assessment, we’ll ask anyone accompanying you to return to the reception area until after your procedure.

Refreshment facilities are available at:

  • Stoke Mandeville Hospital. There’s a restaurant in the main entrance (entrance 3).
  • Wycombe Hospital. There’s a café within reception at main entrance (ground floor of the main tower block).

What can I expect during the examination?

In the endoscopy room we’ll make you comfortable on a trolley and ask you to lie on your left side (this does not apply to patients with a stoma). A nurse will stay with you throughout the test. The procedure is done by a trained doctor or nurse called an endoscopist.

An oxygen probe will be placed on your finger and you’ll be given some oxygen to breathe for the duration of the procedure. You’ll then have a sedative injection if you have chosen to have it. You will have your blood pressure and breathing monitored throughout the procedure.

Gas is introduced to your bowel with the colonoscope to facilitate its passage, so you may feel uncomfortable with wind or feel bloated until you pass the excess ‘wind’ naturally.

Photographs may be taken during your procedure and retained in your medical records as evidence of findings.

The lining of your bowel is insensitive to pain so you shouldn’t feel anything when/if the samples (biopsies) / polyps are removed.

The examination is usually completed within 20 to 30 minutes, but this can vary.

What to expect after the procedure

You’ll rest in recovery afterwards for a short time. During this time nursing staff will check your blood pressure, pulse, respiratory rate and oxygen levels. A doctor or one of the endoscopy nurses will discuss the results of your test with you before your discharge from hospital.

You can start eating and drinking as normal but please be aware that your bowel will work slightly faster because of the residual bowel cleansing medicine.

What are the possible after-effects of the procedure?

You may experience some bloating, wind and cramping in your stomach which can be quite painful at times. This is most likely to be from the gas put in by the endoscopist during your examination. This is normal and the pain should ease within 24 hours.

If you have had a polyp removed or a biopsy, you may experience a little bleeding from your back passage.

If you experience severe abdominal pain or pass more than an egg cup full of red blood, see below and get help immediately.

What are the after-effects of the sedative injection?

If you’ve had a sedative injection, your mental ability to think clearly and make decisions may be affected for up to 24 hours after the procedure even though you feel wide-awake.

For this reason, you must have someone who can take you home and look after you for the rest of the day. You can start eating again as normal.

If you have inhaled a pain control gas (Entonox), you should not drive for at least 30 minutes.

If you’ve had sedation, for 8 hours after your procedure you must not:

  • use potentially dangerous appliances such as a cooker or kettle
  • have a bath unsupervised
  • look after dependants on your own
  • go to work
  • sign any legal documents
  • drink any alcohol
  • take sleeping tablets or recreational drugs.

If you’ve had sedation for 24 hours after your procedure you must not:

  • drive
  • operate potentially dangerous machinery

Advice

Call us if you’re worried about any symptoms you experience after this test.

How to get help after the test

If you have any severe chest or abdominal pain, particularly on swallowing, or if you vomit blood, get help immediately.

During normal office hours

Stoke Mandeville Hospital, 01296 315220

Wycombe Hospital, 01494 425073


Outside office hours

Call Ward 17 at Stoke Mandeville Hospital on 01296 418201.

This is for patients who had their procedure in Wycombe or Stoke Mandeville hospitals.

In an emergency, come directly to Stoke Mandeville Hospital Emergency Department

Follow up information

You’ll need to:

  • see your GP for treatment. Take a copy of the report with you to your GP appointment
  • have your haemorrhoids banded (removed)
  • have an appointment in our outpatients clinic
  • have another investigation
  • talk to your GP and/or consultant about your biopsy results in approximately 8 weeks. We’ll contact you if further action is necessary.

Useful links

Buckinghamshire Healthcare NHS Trust

British Society of Gastroenterology 

Guts UK Digestive Disorders Information