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Flexible sigmoidoscopy

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Flexible sigmoidoscopy is a test to look inside the lower part of your large bowel (the anus, rectum, and ‘sigmoid’ colon). It uses a flexible tube called an endoscope, which has a camera on the end. The procedure can find out the cause of symptoms such as bleeding from your bottom.

About flexible sigmoidoscopy

During a flexible sigmoidoscopy, a doctor will put a tube with a camera attached into your bottom (back passage). They’ll then use this to examine the lining of your bowel and may take pictures or a video of the inside of your bowel.

There are several reasons why your doctor may recommend you have a flexible sigmoidoscopy – for example:

  • you have bleeding from your bottom
  • your pooing habits have changed – for example, you need to poo more often or you have diarrhoea or constipation
  • to check if you have polyps (small wart-like growths in the lining of your bowel) that need to be removed because they can sometimes turn into cancer
  • to look for any changes in existing problems in your bowel – for example, ulcerative colitis or Crohn’s disease
  • to check for bowel cancers

Preparation for a flexible sigmoidoscopy

You’ll usually have a flexible sigmoidoscopy procedure as an outpatient at a hospital. This means you can go home on the same day and won’t usually need to stay overnight.

If you’re having a sedative, you’ll need to arrange for someone to drive you home and stay with you afterwards.

Giving your consent

A specially trained doctor or nurse will carry out your flexible sigmoidoscopy. Before you have the procedure, they’ll talk to you about:

  • why the procedure is being done and if there are any alternative options
  • what will happen
  • what to expect afterwards
  • if there’s any chance of complications (for more information, see our section on complications)

You can ask any questions. Once you have all the information you need and you’re happy to go ahead with the procedure, you’ll be asked to sign a consent form.

Medicines to stop taking

Your hospital will give you instructions about how to prepare for your sigmoidoscopy. You may need to stop taking some of your usual medicines before your procedure. If you’re taking medicines that thin your blood – for example, clopidogrel or warfarin – contact your hospital. They’ll tell you what you need to do.

Having an enema

Your bowel needs to be empty of poo before you have a flexible sigmoidoscopy. You’ll usually need to have an enema. An enema is a liquid that’s injected into your bottom to flush out your bowel, so your doctor has a clear view inside it. You may be asked to:

  • do the enema yourself at home before you come in for your sigmoidoscopy
  • have the enema at the hospital just before your procedure

After the enema, you can’t eat or drink anything before your procedure. This is to make sure that your bowel stays empty.

Sometimes, you may take a laxative instead. This will be in the form of a liquid that you drink to empty your bowel. You usually need to follow a special diet for a couple of days before this. Again, you usually can’t eat anything for a few hours before your procedure but you can continue to drink clear fluids.

Sedation

You don’t usually need to have an anaesthetic or sedative for a flexible sigmoidoscopy. The procedure can be uncomfortable at first, but it doesn’t usually hurt. You can choose to have a sedative if you want to. A sedative will make you feel more relaxed and a bit sleepy, but you’ll stay awake during the procedure. If you have a sedative, your doctor or nurse will inject it into a vein in your hand or arm before they start.

Flexible sigmoidoscopy procedure

A flexible sigmoidoscopy usually takes between five and 15 minutes. You’ll be given a hospital gown to change into, and sometimes a pair of paper shorts to wear

You’ll need to lie on a bed, on your left-hand side with your legs bent. Your doctor or nurse will first gently check your bottom with their finger. They’ll then carefully insert a thin flexible tube (endoscope), using an oily gel to make it as comfortable as possible.

The doctor or nurse will pass small amounts of gas and water through the endoscope to make it easier to see inside your bowel. It may make you feel a bit bloated and like you need to poo, but don’t worry about this because your bowel will be empty.

During the procedure, your doctor or nurse will see pictures from the endoscope on a screen. They’ll gently guide the sigmoidoscope through your bowel. They’ll take pictures and look at the lining of your bowel as they go. They can take small samples (biopsies) from the lining of your bowel if they need to. Your doctor or nurse may remove any polyps they find.

If you find the procedure is really uncomfortable at any time, tell your doctor or nurse and they’ll stop or change what they’re doing. They may offer you pain relief with Entonox (‘gas and air’), which you breathe in through a mouthpiece.

Aftercare for flexible sigmoidoscopy

You may feel bloated or have some mild cramping pain after the procedure. This is caused by the gas that’s used during the procedure. The discomfort usually settles down after a few hours.

If you haven't had a sedative, you’ll be able to go home as soon as you feel ready. If you’ve had a sedative, you’ll be monitored for an hour or two in the endoscopy unit while you recover. You’ll need to arrange for someone to drive you home and stay with you for the rest of the day.

Before you leave the hospital, your doctor or nurse will talk to you about how the procedure went and if they removed any polyps. You may also be given an endoscopy report straight away.

If you had a biopsy or had polyps removed, you may have to wait up to two weeks to get the final results. These may be sent to both you and the doctor who requested your test. You may need to make a follow-up appointment to discuss your results.

Complications of flexible sigmoidoscopy

Like all procedures, a flexible sigmoidoscopy can cause complications. But it’s usually a very safe procedure and complications are rare.

Possible complications of a flexible sigmoidoscopy include the following.

  • Bleeding. This is most likely if you’ve had polyps removed or had a biopsy. The bleeding usually stops on its own without any treatment. But sometimes, you may need another procedure to stop the bleeding.
  • A tear in your bowel (bowel perforation). If this happens, your doctor or nurse may close the tear straightaway. But if this isn’t possible, you’ll need an operation to repair the tear.
  • An infection may occur but this is very rare.

You should immediately contact the hospital or unit where you had the procedure if you have any of the following symptoms after you return home:

  • very bad pain in your tummy or bottom
  • heavy bleeding or bleeding that doesn’t stop from your bottom
  • blood in your poo
  • a high temperature or feel generally unwell

Alternatives to flexible sigmoidoscopy

Your doctor may suggest the following alternatives to having a flexible sigmoidoscopy. What’s best for you may depend on your symptoms, age, and general health.

  • Colonoscopy – this is a lot like a flexible sigmoidoscopy, but it’s used to look at the whole of your large bowel, not just the final part.
  • CT colonography – also called a virtual colonoscopy – involves having CT scans to look inside your large bowel.
  • Colon capsule endoscopy – in this procedure, you swallow a small capsule that contains a tiny video camera. As it passes through your bowel, the camera takes digital pictures that your doctor can see on a monitor.
  • You may need to have more than one test to get a diagnosis. Your doctor will explain your options to you.

Flexible sigmoidoscopy and colonoscopy are very similar. A flexible sigmoidoscopy looks inside the lower part of your large bowel. It examines less than half of your bowel and usually the only preparation needed is an enema.

A colonoscopy looks at the whole of your large bowel. The procedure takes longer (around 30 minutes) and you have to take an oral laxative solution to completely clear the whole bowel.

Polyps are small growths in the lining of your bowel. They don’t usually cause any symptoms or problems. But there’s a small chance that some can change into bowel cancer over time. If your doctor finds any polyps during your flexible sigmoidoscopy, they usually take them out.

A flexible sigmoidoscopy can look inside the bottom part of your lower bowel to check for the cause of symptoms such as diarrhoea, constipation or bleeding from your bottom. It can detect conditions such as cancer.

For more information, see our section about flexible sigmoidoscopy.

To prepare for a flexible sigmoidoscopy, you’ll need to have an enema (or occasionally, a laxative) to empty your bowel. You may need to stop taking some medicines, especially blood-thinning medicines, before your procedure.

For more information, see our section on preparing for a flexible sigmoidoscopy.

You don’t usually need to have a general anaesthetic for a flexible sigmoidoscopy. But you can choose to have a sedative if you want to. This will make you feel more relaxed and a bit sleepy, but you’ll stay awake during the procedure.

For more information, see our section on flexible sigmoidoscopy procedure.

A flexible sigmoidoscopy can be uncomfortable at first, but it isn’t usually painful. If you find the procedure is too uncomfortable at any time, tell your doctor or nurse and they’ll stop or change what they’re doing. They may offer you pain relief with Entonox (‘gas and air’), which you breathe in through a mouthpiece.

For more information, see our section on flexible sigmoidoscopy procedure.

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