A Colonoscopy is a procedure to look at the inside of the large bowel (colon) using a flexible telescope ( See Figure 1. )

Figure 1 - Colonoscopy

Figure 1 – Colonoscopy

This leaflet will give you information about the benefits and risks to help you make an informed decision.  If you have any questions that this leaflet does not answer, you should ask your doctor or any member of the endoscopy team.

Do I need a colonoscopy?

Your doctor is concerned that you may have a problem in the large bowel.  A colonoscopy is a good way of finding out if there is a problem or not.

If the endoscopist (the person doing the colonoscopy) finds a problem, they can perform biopsies (removing small pieces of tissue) to help make the diagnosis.  Sometimes a polyp is the cause of the problem and the endoscopist may be able to remove it during the procedure.

Any alternatives to a colonoscopy?

A colonoscopy is recommended as it is the best way of diagnosing most problems with the large bowel.

Other options include a barium enema (an x-ray test of the large bowel) or a CT Pneumocolon (a special scan of the large bowel).  However, if they find a problem, you may still need a colonoscopy to treat the problem or perform biopsies.

What will happen if I decide not to have a colonoscopy?

Your doctor may not be able to confirm the cause of the problem.  If you decide not to have a colonoscopy, you should discuss this carefully with your doctor.

What does the procedure involve?

Your doctor or a member of the endoscopy team will ask you to sign the consent form once you have read this leaflet and they have answered your questions.

If you take iron tablets, you should stop taking them at least a week before the procedure.

You will need to follow a special diet and you will be given some laxatives to take the day before the procedure.  This is to make sure your bowel is empty so the endoscopist can have a clear view.

If appropriate, the endoscopist may offer you a sedative or pain killer which they can give you through a small needle in your arm or the back of your hand.

The endoscopist will ask you to lie down on your left side in a comfortable position.  A member of the endoscopy team will monitor your oxygen levels and heart rate using a finger clip.  If you need oxygen, they will give it to you through a mask of small tube placed in your nose.

A colonoscopy usually takes between half an hour to three quarters of an hour.  The procedure involves placing a flexible telescope into the back passage and blowing some air into the large bowel to get a clear view.  The endoscopist will be able to look for problems such as inflammation or polyps.  They will be able to perform biopsies and take photographs to help make the diagnosis.  If they find a polyp, it may be possible to remove it during the procedure.

What complications can happen?

The possible complications of a colonoscopy are listed below.  Your doctor may be able to tell you if the risk of a complication is higher or lower for you.

  • Allergic reaction
  • Breathing difficulties or heart irregularities
  • Making a hole in the colon
  • Bleeding from a biopsy site or from minor damage
  • Bleeding, if a polyp is removed
  • Incomplete procedure : This can happen due to a technical difficulty, blockage in the large bowel, complications during the procedure, or discomfort.  Your doctor may recommend another colonoscopy or a different test such as a barium enema.  You should discuss these possible complications with your doctor if there is anything you do not understand.


How soon will I recover?

After the procedure you will be transferred to the recovery area where you can rest and have a drink.  If you were given sedation, you will normally recover in about two hours.  However, this depends on how much sedation you were given.  You may feel a bit bloated for a few hours but his will pass.

Your doctor will tell you what was found during the colonoscopy and will discuss with you any treatment or follow-up you need.  Results from biopsies will not be available for a few days so they may ask you to come back to the clinic for these results.

You should be able to go back to work the day after the colonoscopy unless you are told otherwise.


A colonoscopy is usually a safe and effective way of finding out if you have a problem with your large bowel.  However, complications can happen.  You need to know about them to help you make an informed decision about the procedure.  Knowing about them will also help to detect and treat any problems early.


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