This is a page for patients having a camera test of their lower bowel, as well as their family or carers. It explains why the test is needed, what you have to do to prepare and tries to answer some of the common questions. Please ask us if there is anything that is not clear or if you would like more information.
This is an examination to look at the left side of your large bowel. A small flexible camera is passed into the back passage and air is used to inflate the bowel to make it easier to see the lining. The procedure is quick – usually lasting ten to fifteen minutes – and we will give the results to you before you go home.
There is usually some discomfort with the procedure as the camera goes around the corners in the bowel, but this will not normally last more than a minute or so. There will also be some bloating caused by the air blown into the bowel but this should settle down after the procedure has been completed.
A flexible sigmoidoscopy can be used to look for signs of disease in the large bowel and help your team to find the cause of changes in bowel habit, abdominal pain and bleeding from the back passage.
It is also useful to diagnose and assess common conditions of the bowel which may cause symptoms:
- inflammatory bowel disease
- diverticular disease
- polyps (small growths)
- colorectal cancer
During the procedure a small biopsy may be taken from the lining of your bowel. This does not cause any pain. If we find polyps we may remove these during the procedure. Again, this does not cause any pain.
This is a routine procedure with few side effects or complications. However you should be aware of the following complications:
Bowel perforation – the main risk is the possibility of causing a small tear (perforation) of the bowel. This is rare, but occurs in around one in every five thousand patients. If this happens, you may need a surgical procedure in operating theatres to repair the perforation.
Bleeding – taking biopsies and removing polyps can sometimes result in some bleeding. This can happen up to one week after the procedure and usually stops by itself. A small number of patients who experience bleeding may need to be admitted to hospital for observation.
Missed lesion – although flexible sigmoidoscopy is the best procedure to help diagnose many problems, no procedure is perfect. There is a small risk that we might miss a lesion or other important finding during your procedure.
The vast majority of people tolerate the procedure well with no sedation but, if you feel you need, it we can give you Entonox®. This is the same as the ‘gas and air’ that women can use when in labour. This is an effective painkiller and is completely clear from the body after thirty minutes, allowing you to make your own way home, or even drive. We would not normally offer intravenous sedation for this test.
If you decide not to have the procedure it is important that you inform the Endoscopy Unit and doctor who requested the test as soon as possible. If the test is not performed then we may not be able to find the cause of your symptoms.
Another method of looking at the bowel is to have CT colonography or a colonic capsule endoscopy. However, a sigmoidoscopy has the advantage of being able to remove polyps and take biopsies.
Should a CT scan or colonic capsule endoscopy pick up any disease, then a sigmoidoscopy may still be required. A sigmoidoscopy also avoids X-ray radiation which is needed for a CT scan.
If you are taking warfarin or clopidogrel or other blood thinning agents like dabigatran or rivaroxaban please contact the Endoscopy Unit or your medical team before your procedure. Please stop the following medications seven days before your procedure:
- iron tablets / liquid
- constipating medication e.g. Imodium® (loperamide)
- codeine phosphate
Please continue all other medication as normal.
Some patients, usually children and adolescents, will have their procedure under sedation or general anaesthetic. There is a small risk of an adverse reaction to the medications we use to give sedation or a general anaesthetic. If you are having the procedure under sedation or general anaesthetic you should not eat any food for six hours before the procedure. You can have clear fluids only up to two hours before the procedure.
For the test to be successful the bowel must be empty and clean. A small bottle of fluid (enema) has been provided by the hospital. This is given via a small tube inserted in the back passage. This is a laxative and will help pass faeces out of the bowel. It is a safe medication; people with other health conditions such as diabetes can use it without a problem.
When to use the enema
- Around two hours before your appointment time.
- Do not eat a heavy meal for two hours before using the enema.
- Do not eat after using the enema. You can still drink fluids.
- Use the enema even if you have just opened your bowels.
When not to use the enema
- If you are having constant bloody diarrhoea.
- If in doubt please contact the Endoscopy Unit.
Before using the enema
- Make sure you are near a toilet.
- Find somewhere comfortable to lie down.
- Use a towel to lie on in case of a little leakage.
- You may want to have someone around in case you feel light headed after the enema.
How to use the enema
- Rest the enema bottle in warm water (not hot water) so the fluid does not feel too cold when it goes in.
- Remove the orange cap from the nozzle.
- Lie on your left side with your knees drawn up to your chest.
- Insert the nozzle gently into the back passage.
- Do not continue if it hurts. The feeling may be uncomfortable but it should not be painful.
- Squeeze the bottle until nearly all the liquid has been emptied, then remove the nozzle from the back passage and continue lying down.
- Try to hold the liquid in for as long as possible, ten minutes is ideal but do not worry if you cannot manage this.
- Stay close to a toilet as you may open your bowels more than once.
- Some people do experience mild stomach cramps and some may feel dizzy.
- The effects of the enema will then stop and you should have no problems travelling to the hospital.
- If you have no response to the enema – do not worry. Come into hospital as normal and we can always give you another enema if needed.
- Occasionally you may get some minor irritation that causes bleeding. This is nothing to worry about, but do tell the nursing staff when you arrive for your procedure.
If you feel that you cannot give the enema yourself then please contact the Endoscopy Unit.
We ask a small number of patients to take medication to cleanse all of the bowel. This is provided instead of an enema. If you need this we will send you a separate leaflet about how to take this medication.
We want to involve you in all the decisions about your care and treatment. If you decide to go ahead with treatment, by law we must ask for your consent and will ask you to sign a consent form. This confirms that you agree to have the procedure and understand what it involves. The doctor or specialist nurse performing the procedure will explain all the risks, benefits and alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please speak with a senior member of staff again.
You may experience some bloating or stomach cramps due to the air but this will settle soon after completion of the test. You may feel the urge to pass air during the test, this is normal and we encourage you to do so. You may be asked to change position during the test.
We will take you to the recovery area, where you will be able to get dressed and be discharged.
The doctor or clinical endoscopist performing the test will be able to tell you the results at the time. We will give you a copy of the report about the procedure. If polyps are removed or biopsies taken then the results will be sent to your GP or to the specialist who requested the test. A follow-up appointment will be arranged if one is needed but this will depend on the outcome of the procedure.
If you have any problems after the procedure such as abdominal pain, bleeding, black tarry stools or vomiting then please contact us using the contact information below or go to the nearest Emergency Department.
Can I bring someone with me?
Most patients can come alone since they can go home on their own shortly after the procedure. If you are having sedation or a general anaesthetic you must have somebody to take escort you home and stay with you for 24 hours after the procedure. We encourage escorts to drop you off at the hospital and nursing staff will phone your escort when you are ready to be discharged home, if you need to have someone with you.
Can I still have a flexible sigmoidoscopy if I have my period?
Yes. That will not affect the procedure at all.
Do I need to bring anything?
It would be helpful if you could bring a list of the medicines that you take or bring in the medicines, as these will need to be noted in your records. You can also bring your dressing gown.
If you have had bowel surgery that requires you to wear a stoma bag, please bring a spare bag with you.
Please do not to bring any valuables into the hospital as we cannot accept responsibility for any loss or damage. All your property will stay with you throughout your appointment.
What do I do if I need a translator?
If you need help with translation, please contact the Endoscopy Booking Team.
There are a number of websites which provide more information about having a flexible sigmoidoscopy:
UCLH cannot accept responsibility for information provided by other organisations.
Endoscopy Booking Team (Monday to Friday 09:00-17:00)
Direct line: 020 3456 7022
Switchboard: 08451 555 000 / 020 3456 7890 ext. 67022
E-mail: uclh.
Endoscopy Recovery (Monday to Friday 09:00-17:00)
Direct line: 020 3447 3282
Switchboard: 08451 555 000 / 020 3456 7890 ext. 73282
Address: Endoscopy Unit, University College Hospital, 2nd Floor Podium, 235 Euston Road, London, NW1 2BU
Services
Page last updated: 16 June 2025
Review due: 01 June 2027