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What is a Colonoscopy?

A colonoscopy is a routine test to examine the lining of your bowel, also called the large intestine or colon. This is done using an endoscope, which is a flexible tube, about the thickness of a (little) finger, which has a camera and light at one end. It is passed through the anus (back passage) and carefully moved around the large bowel by a specially trained doctor called an endoscopist.

Why should I have a colonoscopy?

By looking down the endoscope, your endoscopist will be able to get a clear view of the lining of your colon. This will help us to diagnose your symptoms or check any bowel condition that you have had diagnosed in the past. You may have been advised to have a colonoscopy if you have.

  • Bleeding from the bottom (rectum)
  • Pain in the abdomen (tummy) 
  • Persistent diarrea
  • Changes to your bowel habits (diarrhoea or constipation)
  • A strong family history of bowel cancer
  • Have an existing condition that needs reviewing such as Crohn's

What are the risks? 

Serious complications are extremely rare. The most serious risk is the endoscope damaging your colon during the test. This can cause an infection, bleeding or a perforation (tear) of the lining of the bowel. If this happens, your abdomen may become painful and bloated and you may need medicine or surgery to treat the problem. 

If a biopsy is taken or a polyp is removed during the test, you may pass a small amount of blood from your anus after the test. This should only happen up to 12–24 hours after the test and is usually no more than a few teaspoons full. 

Please note that occasionally the test may need to be abandoned or may be incomplete. This can happen if you find the procedure too uncomfortable or if the bowel preparation did not empty your bowel completely. In this case, the test may need to be repeated or we may suggest an alternative procedure. 

Your doctor or specialist nurse will discuss these potential risks with you in more detail. Please ask questions if you are uncertain. 

Are there any alternatives? 

CT (computerised tomography)/CT enema
This is a special type of X-ray machine that can give more details than normal X-rays. However, it cannot be used to take biopsies or remove polyps, so you may still need a colonoscopy. 

A sigmoidoscopy
This is similar to a colonoscopy but only looks at the lower part of the bowel. If your doctor or nurse cannot diagnose your symptoms after this test, you may still need a colonoscopy. 

Faecal occult blood test (FOB)
This tests for hidden blood in your stool, but you may still need a colonoscopy if this test is positive. 

The tests above are generally considered to be less accurate than a colonoscopy and some of them involve radiation.

Giving my consent (permission) 

We want to involve you in decisions about your care and treatment. If you decide to go ahead, you will be asked to sign a consent form. This states that you agree to have the treatment and you understand what it involves. 

If you would like more information about our consent process, please speak to a member of staff caring for you. 

How can I prepare for a colonoscopy? 

You will also receive a separate leaflet to explain how to prepare for your colonoscopy with a restricted diet and bowel preparation medication Diet advice and Bowel Preparation for your Colonoscopy. To make sure the doctor or nurse has a clear view of your colon, it must be completely empty. Therefore, you will be asked to follow a special diet for a few days before the procedure. 

You will have to take a laxative (substance that speeds bowel movement) before the test. This will be prescribed by your doctor in clinic. If you have any questions about the test, you will be able to discuss them at this time. 

You will also need to drink more fluids on the day before your colonoscopy. You should aim to drink a glass of water every hour. 

Before the procedure 

If you are taking any medicines that thins your blood, such as antiplatelet medicines (for example aspirin or clopidogrel) or anticoagulant medicines (for examples warfarin or rivaroxaban), please tell your doctor or the nurse as you may need to stop them temporarily before your procedure. Also tell your doctor or nurse if you have diabetes as you may need to alter the dose of your diabetes medicines, as you will need to fast before the procedure. Further information on stopping any medicines will be given to you when you come for pre-assessment. Please ask us if you have any questions. 

Please let us know if you are taking any regular medicines (including anything you buy yourself over the counter or any herbal or homeopathic medicines) and if you have any allergies to any medicines. 

You should continue to take all of your medications as normal, unless you have been told otherwise by the doctor or endoscopy nurse. 

When you arrive at the endoscopy unit 

On arrival, please give your name to the receptionist or nurse. Please be aware that we have our endoscopist teams running up to five procedure rooms at the same time so sometimes another patient who arrived after you may be called in before you are. This does not mean you have been forgotten, but that the other person is on a different list to you. We do everything we can to avoid keeping you waiting any longer than necessary, but because every procedure takes a different length of time to complete, sometimes it’s hard to give exact timings. We’ll update you regularly as to how long you are likely to be with us. But please be prepared to be with us for the whole morning or afternoon, depending on whether you are a morning or afternoon admission. 

At check in we will ask you to wait in the waiting area until you are seen by an endoscopy nurse, who will ask you about your medical history. Please tell the nurse if you have had any reactions or allergies to other examinations in the past. 

In case there are polyps present, we will ask you to take off all your jewellery before the examination. This is because you should not wear any metal for the technique we use to remove polyps. Because of this, you may wish to leave any valuable jewellery at home, as we cannot be responsible for any valuables lost while in the unit. 

You will be asked to remove all of your clothing and change into a gown and some dignity disposable underwear. You may want to bring your dressing gown and slippers with you (we do supply non slip socks). Once you are ready you will be taken to the second waiting area, signposted ‘sub wait area.’ Your endoscopist will explain more about the procedure and answer any questions you may still have. 

What happens during the procedure? 

This test is normally performed with sedation or an injection of painkillers but you can choose not to have sedation if you wish. This is medication that makes you relaxed and sometimes sleepy but does not put you to sleep. Your endoscopist will explain this to you in more detail. 

If you are concerned about pain or discomfort you may wish to consider using Entonox® for pain relief. You may already know that Entonox® is used to relieve pain during childbirth. It is also used widely by the ambulance service and in hospitals for a variety of procedures and conditions. 

The test itself only takes about 30 minutes and an endoscopy nurse will be present throughout for reassurance. 

You will be asked to lie down on your left-hand side on a couch with your knees bent. The endoscopist will start by inserting a finger into your anus to perform a rectal exam, this will help lubricate the anal passage and identify if there are any significant haemorrhoids or growths able to be felt in your anal passage. 

The endoscope will then be inserted into your lower bowel through your anus. Air will be passed down a channel in the endoscope, expanding your bowel to make it easier to see the lining. This may make you feel slightly bloated and you may feel the urge to go to the toilet, but you will not be able to do this as your bowel will be empty. Many people pass some wind during the test. This is perfectly normal and is nothing to be embarrassed about. 

If polyps are present, your endoscopist can remove these. You will not feel this. When a polyp is particular big or in a difficult position the removal may be deferred and re-booked on a specialised list. 

Will I feel any pain? 

You may have some cramping and discomfort due to the air used to inflate your bowel or brief periods of discomfort particularly when the endoscope is first inserted and when the scope passes around bends in your bowel. Occasionally the nurse will press gently on your stomach or your position may be altered to aid the passage of the scope. You will be given painkillers through a needle that will be inserted into a vein to help keep you comfortable. You will not feel anything if any biopsies are taken 

What happens afterwards? 

After the procedure you will be taken to the recovery area. If you have had sedation, you will need to rest quietly until your observations are stable (usually an hour). The nurse will check your blood pressure and pulse and will take you to the discharge area when you are stable. You can bring your own sandwich or other snacks with you if you are concerned that you will be very hungry otherwise you will be offered some tea and biscuits in the discharge waiting area. 

If you have not had sedation you will be escorted to the discharge area where a nurse will explain your results and give you a copy for your own records. You will be able to leave as soon as the nurse has given this to you. 

If you choose to have sedation, you must arrange for a relative or friend to take you home approximately one hour after the test. This person should be 18 years of age or older. It is recommended that someone stays with you overnight. You will not be able to drive or operate any machinery for the remainder of the day and will need to rest quietly at home. Please note that your appointment will be cancelled on the day if you wish to have sedation but have not organised an escort home. . If you are unable to arrange someone to collect you, please contact us to discuss alternative arrangements. 

What do I need to do after I go home? 

The sedation lasts longer than you may think and therefore you must not:

  • Drive or ride a bicycle
  • Operate machinery or do anything requiring skill or judgement
  • Drink alcohol 
  • Take sleeping tablets
  • Go to work
  • Make any important decisions, sign contracts or legal documents

You should rest at home following your procedure and should be able to carry out your normal activities 24 hours after the test. 

You should consult your GP or go straight to your nearest Emergency Department (A&E) if you develop severe abdominal (tummy) pain, a fever or are vomiting or passing large amounts of blood after the test. (Please take your endoscopy report with you). 

When will I get the results? 

The doctor or specialist nurse will often be able to tell you your results before you leave the hospital. If you have had a sedative, it is a good idea to have someone with you when the results are being discussed, as you may not remember all of the details afterwards, due to the sedative. If you have had biopsies taken the results may take up to one week to become available.