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Flexible sigmoidoscopy

Flexible sigmoidoscopy is a procedure that’s used to look inside the lower part of your large bowel. It can be used to check your bowel for signs of cancer, to investigate symptoms of bleeding, and to check bowel conditions that you may have been diagnosed with in the past. It can also be used to find and remove polyps in your bowel.

A doctor talking to a patient

About flexible sigmoidoscopy

Your doctor uses a flexible tube called a sigmoidoscope to see inside your bowel. The sigmoidoscope has a light, and a camera and surgical tools can be used inside it. Your doctor can examine the lining of your bowel as well as take tissue samples (biopsies) and remove polyps.

Flexible sigmoidoscopy is part of the bowel cancer screening programme in England. As part of the screening, it’s called bowel scope screening and it’s currently being offered to men and women aged 55 and over. There are two parts to the screening. Firstly, you have a sample of your stool (faeces) checked to see whether there are small amounts of blood in it. If there are, then you will be offered a flexible sigmoidoscopy to check your bowel.

You will meet the doctor carrying out your procedure to discuss your care. It might be different from what we’ve described here because it will be designed to meet your individual needs.

Deciding on flexible sigmoidoscopy

This information can help you understand the pros and cons of having a flexible sigmoidoscopy. Think about how important each issue is to you, and then talk to your doctor. You can work together to decide what's right for you.


  • Flexible sigmoidoscopy allows your doctor or nurse to see inside your bowel clearly so that signs of cancer or polyps can be seen.
  • When it’s used as part of cancer screening and treatment, flexible sigmoidoscopy has been found to help reduce the number of people dying from bowel cancer.
  • You shouldn’t need an anaesthetic or sedative for flexible sigmoidoscopy, and it’s usually painless.
  • If your doctor finds any polyps during your procedure, they may be removed at the same time.


  • You will need an enema before the procedure, which may be unpleasant.
  • There is a very small risk (1:10,000) that during the procedure your bowel might be damaged, or you might have some bleeding afterwards.
  • Flexible sigmoidoscopy can only look at part of your bowel, so you may need further tests.

Preparing for a flexible sigmoidoscopy

You’ll be given information about what you need to do before you have your sigmoidoscopy. It may be possible to choose where you have your procedure. You might be told about units with a JAG accreditation, if this is an option for you. This comes from The Joint Advisory Group on Gastrointestinal Endoscopy (JAG), which is part of the Royal College of Physicians. If you’d like to find out more, visit their website for further information.

If you’re taking iron tablets, codeine or medicines to prevent diarrhoea you should stop taking these before the procedure. If you keep taking these medicines, it may be harder to clean your bowel, making it more difficult to see any problems during the procedure.

If you’re taking medicines that affect how quickly your blood clots, you may be asked to stop taking them just before your procedure. This will depend on what your flexible sigmoidoscopy is for.

Your surgeon or nurse will tell you when to stop taking any medicines.

Your bowel needs to be empty for your doctor to be able to see it clearly, so you will need to have an enema. An enema is a small amount of fluid, which you squeeze into your back passage from a pouch attached to a nozzle. Once the fluid is in, you hold it in for 5 to 10 minutes until you feel the urge to go to the toilet.

You can give yourself the enema at home a couple of hours before the sigmoidoscopy. If you’re not able to give yourself the enema, you can have it at the clinic or hospital just before the procedure.

You can eat and drink as usual until you have the enema. Then you may be asked to stop eating, but you should be able to have clear fluids to drink. This means liquids without milk, for example, water, black tea or coffee.

Your nurse or surgeon will discuss with you what will happen before, including any discomfort you might have. If you’re unsure about anything, ask. Being fully informed will help you feel more at ease and will allow you to give your consent for the procedure to go ahead. You will be asked to do this by signing a consent form.

What are the alternatives to flexible sigmoidoscopy?

There are several alternatives to having a flexible sigmoidoscopy, depending on your symptoms and your general health. The main ones are listed below.

  • Colonoscopy. This is like a flexible sigmoidoscopy, but it’s used to look at the whole of your large bowel, not just the lower part.
  • CT colonography. This is a computerised tomography (CT) scan of your abdomen which produces detailed images of the inside of your bowel.
  • Proctoscopy. This is like a sigmoidoscopy, but it only looks at the very end of your bowel.

You may need to have more than one test to get a diagnosis. Your doctor will explain your options to you.

What happens during a flexible sigmoidoscopy?

A flexible sigmoidoscopy can be done as an out-patient, which means you shouldn’t need to stay in hospital. It usually takes between five and 15 minutes and can be done by a doctor or a nurse. It can sometimes be uncomfortable, but it shouldn’t be painful.

You may be asked to put on a gown before your procedure.

You probably won’t need a sedative (this helps you to relax) for this procedure. However, if you do, it will be given as an injection into a vein in your hand or arm. If you are given sedation you will be advised not to drive for 24 hours, and will need someone to be able to take you home after the procedure.

You will be asked to lie on your left-hand side with your legs bent. Your doctor or nurse will gently examine your back passage using a gloved finger. They will then carefully put in the sigmoidoscope, using lubricating jelly to make it as comfortable as possible.

To make it easier to see your bowel, air or carbon dioxide gas is passed through the sigmoidoscope into your lower bowel to make it expand a little. This can make you feel a bit bloated.

During the procedure, your doctor or nurse will be able to see the images from the sigmoidoscope on a screen. They will move the sigmoidoscope through your bowel taking images and examining the lining of your bowel. They will also be able to take small samples from the lining of your bowel and may remove polyps. This is done by passing instruments through the sigmoidoscope.

What to expect afterwards

If you haven't had a sedative, you should be able to go home when you feel ready.

If you have had a sedative, you will need to stay a little longer. A nurse will monitor your blood pressure and pulse while you recover. You will need to arrange for someone to drive you home and stay with you for the rest of the day.

Before you leave, your doctor or nurse may talk to you about what they have seen during the procedure. You will usually be given a copy of the medical report too. If you’ve had a biopsy (or had polyps removed), you may have to wait up to two weeks to get the results. These are usually sent to the doctor who requested your test, and they will talk to you about what they mean.

Side-effects of flexible sigmoidoscopy

Side-effects describe the unwanted, but mostly temporary effects you may get after having a flexible sigmoidoscopy.

Your abdomen might feel uncomfortable or you might feel bloated. This is caused by the air or carbon dioxide used during the procedure and usually settles after a few hours. Contact your doctor if the pain continues for longer than this.

Complications of flexible sigmoidoscopy

Complications are when problems occur during or after the flexible sigmoidoscopy. They are very rare, but the serious ones are listed below.

  • A tear in your bowel (bowel perforation). Having polyps removed or biopsies taken can lead to a tear. You may need an operation to repair it and are likely to be admitted to hospital. Very rarely, the manipulation of the sigmoidoscopy itself can cause damage, particularly if the bowel is weakened already, for example by diverticular disease or inflammation.
  • Bleeding. This is most likely if you have had polyps removed or a biopsy taken. This usually stops on its own without any treatment. If you have any heavy bleeding, contact the hospital where you had the procedure.

If you’ve had a sedative during the procedure you will need to be closely monitored. Sedatives can occasionally cause problems with your breathing, blood pressure and heart rate.

FAQ: What’s the difference between a sigmoidoscopy and a colonoscopy?

Flexible sigmoidoscopy is similar to a colonoscopy, but uses a short instrument to look inside your rectum and the lower part of your bowel only. A colonoscopy looks at the whole of your bowel. Both work well as tests for bowel cancer. Which one you have may depend on the exact problem that your doctors want to check.

FAQ: What are polyps, and why do they need removing?

Polyps are small growths of the lining inside your bowel. They’re common and don’t usually cause any symptoms. Most polyps don’t cause any problems but there is a small chance that certain types can change into cancer over time. If your doctor finds any polyps during your flexible sigmoidoscopy, they will usually remove them.


  • Bowel treatment on demand

    You can access a range of our health and wellbeing services on a pay-as-you-go basis, including bowel treatment.

  • Other helpful websites Other helpful websites

    Further information


    • Flexible sigmoidoscopy. Medscape., last updated February 2016
    • Colonic polyps. BMJ Best Practice., last updated August 2016 
    • Colorectal assessment. Oxford handbook colorectal surgery (online). Oxford Medicine Online., published online October 2010
    • Bowel cancer screening: programme overview. Public Health England., last updated November 2015
    • Schoen R, Pinsky P, Weissfeld J, et al. Colorectal-cancer incidence and mortality with screening flexible sigmoidoscopy. N Engl J Med 2012; 366:2345–357
    • Quality assurance guidelines for colonoscopy. NHS Cancer Screening Programmes 2011.
    • Veitch A, Vanbiervliet G, Gershlick A, et al. Endoscopy in patients on antiplatelet or anticoagulant therapy, including direct oral anticoagulants: British Society of Gastroenterology (BSG) and European Society of Gastrointestinal Endoscopy (ESGE) guidelines. Gut 2016; 65:374–89 
    • Flexible sigmoidoscopy. Cancer Research UK., updated February 2016
    • Colorectal cancer: diagnosis and management. National Institute for Health and Care Excellence (NICE) December 2014,
    • Guidance on the use of CT colonography for suspected colorectal cancer. British Society of Gastrointestinal and Abdominal Radiology and The Royal College of Radiologists., published 2014 
    • Colorectal cancer. PatientPlus., last checked October 2014
    • Barium enema examination. PatientPlus., last checked October 2014 
    • Bowel cancer screening. Beating Bowel Cancer., published February 2015
    • Safe sedation practice for healthcare procedures. Academy of Medical Royal Colleges., published 2013
    • Colorectal cancer screening. GP Update Handbook (online). GP Update Ltd,, accessed August 2017
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  • Author information Author information

    Reviewed by Alice Rossiter, Specialist editor, January 2017.
    Expert reviewed by Mr Simon Phillips, Consultant Colorectal Surgeon.
    Next due for review: January 2020.

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