Flexible sigmoidoscopy

A flexible sigmoidoscopy is a test to look inside the lower part of your large bowel.

A specialist doctor or nurse (endoscopist) uses a flexible sigmoidoscope for this test. This is a thin, flexible tube that has a small light and a camera at one end. You may also hear it called an endoscope or a colonoscope. The endoscopist puts the tube into your back passage (anus). Then they gently move it up into the lower part of your bowel. They can see the pictures of the inside of your bowel on a TV screen.

You usually have this test in the endoscopy unit at the hospital. It may take between 10 to 20 minutes. But you should expect to be in the department for up to 2 hours. This is to allow time for any preparation and recovery afterwards. 

The short video below explains what it's like to have a flexible sigmoidoscopy.

Why you might have a flexible sigmoidoscopy

There are a number of reasons why you might have a flexible sigmoidoscopy, including:

• to help find the cause of your bowel symptoms

• to check a bowel condition that you have been diagnosed with in the past

Before your test

You will have information from the endoscopy staff explaining how to prepare for your flexible sigmoidoscopy. It’s important that you read and follow the instructions. There is usually a number to call if you have any questions.

Your bowel needs to be empty of poo for a flexible sigmoidoscopy. This is so the endoscopist has a clear view of your bowel.  

To prepare you for the test:

• you may have an enema - you might be sent this to do at home or you may have it when you get to the hospital 
• instead of an enema, you might be sent a laxative to drink and follow a special diet for a couple of days beforehand 
• you usually can't eat or drink for a few hours before your appointment time

If you're taking iron tablets or drugs that can cause constipation, you need to stop taking them about a week before your appointment. Your appointment letter gives you more details about this. 

Contact the endoscopy staff for advice before your appointment if you are diabetic or taking medicines to thin your blood. They will tell you if you need different instructions to prepare your bowel and if you need to have a different diet beforehand. They will also tell you if you need to stop taking any medicines before the test. 

Your letter will tell you when to stop eating and drinking. 

How you have a flexible sigmoidoscopy

When you arrive at the hospital you are seen by a nurse. They will check your temperature, blood pressure, breathing and heart rate.

You also see your endoscopist. They will explain what will happen and ask you to sign a consent form. This is a good time to ask any questions you may have. 

Your nurse will give you a hospital gown to change into. You might also wear paper shorts with an opening at the back.

During the test

You lie on a bed on your left side, with your knees tucked up to your chest. You don't normally need medication to make you relax (sedation) while you have the test. But some people may have it. It is given through a cannula that is put into the back of your hand. 

The endoscopist will first check your back passage for any abnormalities. They then gently put the endoscope into your anus and up into the lower part of large bowel. This is uncomfortable but is not usually painful. They put gel on the endoscope to make it more comfortable. The gel usually feels cold. 

The endoscopist may put a small amount of gas or air through the endoscope into your bowel. This opens the bowel so they can see the lining clearly. This can make you feel bloated and uncomfortable, and you might have tummy cramps. You may pass wind during the procedure. Don’t feel embarrassed, this is normal for this test. 

If you find it too uncomfortable at any stage tell the endoscopist and they will stop. You might have pain relief using gas and air (Entonox). This is a fast acting pain relief breathed in through a mouthpiece. 

During the test, they take photographs of your bowel lining. If your endoscopist sees any abnormal areas they will take tissue samples (biopsies). If you have any growths in the bowel lining (polyps), they can be removed through the endoscope.

The tissue biopsies and polyps go to the laboratory and are checked by a pathologist .

After the test

You might feel bloated and have mild cramping pain after the test. 

After a flexible sigmoidoscopy without sedation

You can eat and drink as usual and you can usually go home soon after the test.  

After a flexible sigmoidoscopy with sedation

You stay in the department for about an hour until you are less drowsy and the sedation has worn off. Your nurse monitors you during this time.

It is important to have someone with you so they can take you home and stay with you overnight. Also for 24 hours after having the test with sedation you shouldn’t drive, drink alcohol, operate heavy machinery or sign any legally binding documents.

Possible risks of having a flexible sigmoidoscopy

Flexible sigmoidoscopy is a very safe procedure. Your nurse will tell you who to contact if you have any problems after your test. Your doctor ensures that the benefits of having a sigmoidoscopy outweigh any possible risks.

Tummy discomfort or pain

You may have some bloating, cramping or pain in your tummy (abdomen) after the test. This is due to the gas or air put into the bowel. This should go away after a few hours. Walking around, warm drinks and peppermint water may help you to pass wind.

Bleeding

After having a biopsy or polyp removed, you might have some bleeding. This is usually a small amount and stops on its own within a couple of days. Sometimes people with piles (haemorrhoids) may have some bleeding after the test.  

Infection

This is rare, but you may get a high temperature and generally feel unwell. 

Tear in your bowel

Very rarely, you might have a small tear in the bowel wall (perforation). If this happens it's likely you will need surgery to repair the tear. 

Your nurse will give you instructions about what to look out for and who to contact if you have any problems at home. 

Contact the department where you had your test or your GP if you have the following symptoms:

• severe tummy or bottom pain

• continuous or heavy bleeding from your back passage

• passing blood clots from your back passage

• passing black poo (stools)

• high temperature

• generally feeling unwell

Getting your results

You should get your results within 2 weeks. They may be sent to you and your GP or you may get them at a follow up appointment. 

The endoscopist will explain to you at the time if they've taken any biopsies or polyps. They won't be able to give any more information than this. This is because the pathologist needs to look at them in the laboratory under a microscope.  

Waiting for test results can be a very worrying time. You might have contact details for a specialist nurse. You can get in touch with them for information and support if you need to. It may help to talk to a close friend or relative about how you feel.

Contact the doctor who arranged the test if you haven’t heard anything after a couple of weeks.

More information

We have more information on tests, treatment and support if you have been diagnosed with cancer.