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Bowel picture.


Before you have your colonoscopy, you should have been asked to complete a FIT test (Faecal Immunochemical Test) which checks for traces of blood in your poo. Your GP will provide a FIT test pack for you to use to collect your sample, which should then be returned to your GP as soon as possible for analysis.

A colonoscopy is a test to check inside your bowels. It is performed using an instrument called a colonoscope, which is a long, thin, flexible tube with a light and a camera at one end. The camera sends images of the inside of your bowel to a television screen.

During the investigation, the endoscopist may need to take some tissue samples, known as biopsies, from the lining of your large bowel for further analysis. This is completely painless. Photographs may also be taken for your medical records.

Why might you have been referred for a colonoscopy?

You have been advised to have a colonoscopy to try and find the cause of your symptoms, help with treatment and, if necessary, to decide on further investigations. Common reasons for people to have a colonoscopy include:

  • A change in your usual bowel habit to constipation or diarrhoea.
  • Bleeding from the back passage.
  • To find the cause of anaemia.
  • Abdominal pain.
  • To review a known bowel condition (e.g. inflammatory bowel disease, colonic polyps).
  • To assess or treat an abnormality seen on other tests such as barium enema or CT scan.
  • A strong family history of bowel cancer.
  • As part of the national bowel cancer screening programme.

If none of these apply to you, your doctor will explain any other reasons there may be for having this test.

It should take 30 to 45 minutes to have your colonoscopy. But you might be at the hospital for around 2 hours from getting there to going home.

It is important that you are comfortable during the procedure to ensure that the endoscopist can perform the procedure successfully.

Some people opt to have a sedative to make them drowsy and relaxed for the procedure.

Alternatively, you could have gas during the procedure which will help to ease any pain or discomfort and has a calming effect.

This means you will still be awake but will be drowsy and have reduced awareness about what’s happening.

We know some people can feel anxious or worried when they are told they need a colonoscopy, but it is important to have this test if you are referred. Bowel Cancer UK have launched a Colonoscopy Confidence campaign to explain what colonoscopy is.

While you are waiting for your colonoscopy, ensure you maintain a healthy diet, reduce alcohol, and consider stopping smoking. Try and avoid being too constipated by taking laxatives regularly if needed. This will also help to ensure that your bowel is fully emptied when you take the bowel preparation before the procedure. Avoid any food that make your bowel symptoms worse. If you are being investigated for diarrhoea, ensure that you are drinking plenty of fluids to remain hydrated.

Once your colonoscopy is scheduled, the hospital will send you some instructions about how to prepare. It is extremely important that your bowel is completely empty before a colonoscopy to allow adequate inspection of the lining of your colon. If you are taking iron tablets, then stop these 7 days before the test.

For 2 days before a colonoscopy, you should only eat plain foods like:

  • Plain chicken not in sauce.
  • White rice, pasta, or bread.
  • Clear soup.

You will find the necessary information on your letter from the hospital.

The day before your colonoscopy you’ll need to drink sachets of laxatives to empty your bowels ready for the test.

Most people:

  • Need to drink a few sachets.
  • Need to drink the sachets at different points throughout the day.
  • Get diarrhoea a few hours after taking the first sachet. Stay at home and be near a toilet after you’ve started drinking the laxatives.

It is very important to follow the instructions within your letter from the hospital, otherwise the specialist may not be able to do your colonoscopy. If you have any questions about the instructions when you receive them, get in touch with your hospital team.

What should you do if your health is deteriorating?

If you develop new symptoms such as blood mixed in your stools, severe pain, not passing stools or wind, or rapid weight loss then contact your GP or specialist as you may need a more urgent review. Equally, if you have existing symptoms that have changed in nature or deteriorated quickly then you should seek further advice and reassessment.

If your appointment has come through but your condition is getting worse, you should contact the hospital team or Patient Advice and Liaison Service (PALS). The number and email for this should be on the hospital appointment letter.

If you haven’t yet received your hospital appointment and your condition is getting worse, you should contact your GP practice. Your GP cannot get you seen quicker at the hospital as they don’t have access to the waiting list or appointment system.

However, if your condition is getting worse or if you are experiencing new symptoms they can assess the situation, give you some advice and may be able to update your specialist to consider upgrading your procedure.

Alternatively, the NHS 111 service is available if you have a medical problem and aren’t sure what to do. To access NHS 111, visit 111 online or call 111. The service operates 24 hours a day, 7 days a week.

BSL users can use the NHS video interpreter service.

Last Updated: 12 April 2024

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