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Colonoscopy
Published by Bupa's health information team, February 2009.
This factsheet is for people who are planning to have a colonoscopy, or who would like information about it.
A colonoscopy is a procedure that allows the doctor to look inside the large bowel (colon and rectum).
Your care will be adapted to meet your individual needs and may differ from what is described here. So it's important that you follow your doctor's advice.
About colonoscopy
A colonoscopy is performed using a narrow, flexible, telescopic camera called a colonoscope. Your doctor will pass the colonoscope into your bowel through your rectum (back passage). A colonoscope can help find out what is causing symptoms such as:
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persistent diarrhoea or change in bowel habit
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bleeding from your rectum
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anaemia
It's also used to check for certain bowel conditions such as:
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inflammation (for example, ulcerative colitis or Crohn's disease)
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early signs of bowel cancer
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polyps (adenoma)
Sometimes, a colonoscopy is used to confirm the results of other tests, such as the faecal occult blood (FOB) test, which is used in routine screening and looks for hidden blood in your faeces.
During the procedure, your doctor may also remove any polyps (small growths of tissue) found on your bowel wall. Polyps are usually benign (not cancerous), but can become cancerous over a number of years. Most bowel cancers are thought to develop from a pre-existing polyp.
What are the alternatives to colonoscopy?
A colonoscopy is the most sensitive test for detecting polyps. However, depending on your symptoms, it may be possible to diagnose your bowel condition using a different imaging test, such as an X-ray using a barium enema, a CT (computed tomography) scan or a flexible sigmoidoscopy.
Preparing for your procedure
Colonoscopy is usually done in a hospital as an out-patient or day case. This means that you won't need to stay overnight.
Your hospital will write to you with instructions to follow before your colonoscopy. Your bowel needs to be completely empty so that your doctor can see the bowel wall clearly.
You will usually be asked to:
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stop eating solid food the day before the test
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drink plenty of clear fluids in the 24 hours before your test
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take a strong laxative - the effects of this laxative can be quite powerful and you will need to stay close to a toilet
If you normally take medication (eg tablets for blood pressure), continue to take this as usual, unless your doctor tells you not to. Your doctor may ask you stop taking certain medicines such as aspirin, which increase the risk of bleeding.
At the hospital your nurse may check your heart rate, blood pressure, take a blood sample and test your urine.
Colonoscopy is usually done under sedation to make sure you're relaxed and comfortable during the procedure. If you have a sedative, you won't remember much about the test.
Your doctor will usually ask you to sign a consent form. This confirms that you understand the risks, benefits and possible alternatives to the procedure and have given your permission for it to go ahead.
About the procedure
The procedure usually takes 30 to 60 minutes to complete.
Your nurse will ask you to put on a hospital gown that opens at the back, and to rest on your side.
If you're having sedation, this is usually given through a small plastic tube (cannula) in a vein on the back of your hand. You should start to feel relaxed and drowsy almost immediately.
Sedatives can sometimes affect your breathing. While you're sedated, your doctor will monitor the amount of oxygen in your blood through a sensor on your finger and will give you extra oxygen through a mask.
With you lying on your left side, your doctor will gently insert the colonoscope into your rectum. Lubricating jelly will be used to make this as easy as possible.
Air is pumped through the colonoscope and into your bowel to make it expand and your bowel wall easier to see. When this happens, you may briefly feel discomfort and you may pass some wind.
The camera lens at the end of the colonoscope sends images from the inside of your colon to a monitor. Your doctor will look at these images to examine your bowel. During the procedure, you may be asked to change your position - for example turning from your side on to your back. This helps your doctor to examine different areas of the colon more easily.
If necessary, your doctor will take a biopsy (a small sample of tissue) and/or remove small growths of tissue called polyps. This is done using special instruments passed inside the colonoscope, and is quick and painless, although you may feel a slight pinch. The samples will be sent to a laboratory for testing to determine the type of cells and if they are benign or malignant (cancerous).
When the test is finished the colonoscope is taken out quickly and easily, sucking out the air that has been pumped in. The colonoscopy won't hurt but it may be a bit uncomfortable.
 Where a colonoscope is passed
What to expect afterwards
You will need to rest until the effects of the sedative have passed. You will usually be able to go home when you feel ready, although you may need to stay in a bit longer if a polyp has been removed. You will need to arrange for someone to drive you home.
You should try to have a friend or relative stay with you for the first 24 hours.
Results
If you have a biopsy or polyps removed, your results will be ready several days later and will usually be sent to the doctor who recommended your test. At the hospital, your doctor may discuss other findings from the colonoscopy with you before you leave, or you may be given a date for a follow-up appointment.
Recovering from a colonoscopy
If you need pain relief, you can take over-the-counter medicines, such as paracetamol or ibuprofen. Always read the patient information that comes with your medicine and if you have any questions, ask your pharmacist for advice.
Sedation temporarily affects your co-ordination and reasoning skills, so you must not drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. If you're in any doubt about driving, always follow your doctor's advice and please contact your motor insurer so that you're aware of their recommendations.
Most people have no problems after a colonoscopy, but you should contact your doctor if you:
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have heavy bleeding from your back passage
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have abdominal pain which gets worse, or is more severe than any pain that you had before the test
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develop a high temperature
What are the risks?
Colonoscopy is commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.
Side-effects
These are the unwanted, but mostly mild and temporary effects of a successful procedure.
After having a colonoscopy you may:
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feel bloated and have slight discomfort due to trapped wind
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feel sleepy as a result of the sedative
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have slight bleeding from your back passage if you have had a biopsy or polyp removed
Complications
This is when problems occur during or after the procedure. Most people aren't affected.
Your doctor will be experienced at performing colonscopies, but even so, a few aren't successfully completed and may need to be repeated.
Other complications are uncommon but it's possible to:
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have a reaction to the sedative, such as a skin rash, difficulty in breathing or heart problems
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damage, or very rarely, tear the colon, particularly if a biopsy is taken or a polyp is removed, which may need further surgery or treatment with medicines
The exact risks are specific to you and differ for every person, so we haven't included statistics here. Ask your doctor to explain how these risks apply to you.
Related topics
Further information
Sources
- Longmore M, Wilkinson IB, Rajagopalan S. Oxford Handbook of Clinical Medicine. 6th ed. Oxford: Oxford University Press, 2004:228
- Bowel cancer screening - the colonoscopy investigation. NHS Cancer Screening Programmes, 2006. www.cancerscreening.nhs.uk
- Brown SR, Baraza W, Hurlstone P. Chromoscopy versus conventional endoscopy for the detection of polyps in the colon and rectum. Cochrane Database of Systematic Reviews 2007, Issue 4. Art. No: CD006439.pub2. www.cochrane.org
- Examining the bowel. Cancer Research UK. www.cancerhelp.org.uk, accessed 15 May 2008
- Guidelines on safety and sedation for endoscopic procedures. British Society of Gastroenterology, 2003. www.bsg.org.uk
- Epstein O. Complications of colonoscopy. BSG Guidelines in Gastroenterology, 2006. www.bsg.org.uk
- Personal communication, Mr S Pollard, Consultant General Surgeon, Spire Leeds Hospital, 19 July 2008
- Personal communication, Ms B Jones, Nurse Advisor, Beating Bowel Cancer, 23 July 2008
- Atkins WS, Saunders BP. Surveillance guidelines after removal of colorectal adenomatous polyps. Gut 2002; 51:v6-v9. www.bsg.org.uk
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: February 2009
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