Colonoscopy

What is a colonoscopy?

A colonoscopy is a procedure that allows the doctor to look at the inside of your colon (also called the large bowel or intestine) with a soft flexible tube inserted through your rectum (back passage).
Although colonoscopy is a safe procedure it is possible that your colon may be injured during the procedure. To reduce the risk of any injuries it is important that you follow the instructions below to prepare your colon properly.

Alternatives to colonoscopy for investigation of the bowel:

Colonoscopy is considered the “gold standard” for investigating the colon. An alternative, but less sensitive investigation is a barium enema examination. This requires the same bowel preparation as is required for colonoscopy (see next section) but does not require sedation or general anaesthesia (usually). Very recently, what is known as a “virtual colonoscopy” which again involves bowel preparation followed by a special form of CT scan. This is not yet wildly available but in time may come to replace routine colonoscopy examinations.

Obviously, it is your choice whether to have the colonoscopy examination (with the best chance of making an accurate diagnosis) or to opt for the slightly less sensitive barium enema examination. If you have any polyp or other pathology then we can remove the polyp or biopsy any other abnormality at the same time as doing a colonoscopy where as, of course, this can not be done during a barium enema examination.

Preparing your colon

When you receive your appointment letter to attend the hospital for this test, you will also receive some instructions on how to empty and prepare your bowel. These will include a preparation to take the day before and a diet sheet advising you what you should eat and drink the days leading up to the investigation. Be sure to read these instructions carefully, it is essential that you clean out the colon, as this will determine the success of the procedure.  

Medication

You may take your regular tablets as usual on the day of the examination (except iron tablets). If you take Aspirin or Warfarin or are a diabetic your admission letter will request you to contact the Endoscopy Unit for further advice.

The procedure

When you arrive at the Endoscopy Suite the nurses will welcome you and prepare you for the procedure. Everything will be done to ensure your comfort.

Once the doctor has checked your medical history, medications, explained the procedure and you have signed the consent form, the nurses will position you on a trolley. A cannula (small needle) will be put into the back of our hand and you will be given medication to make you relaxed and drowsy. Although you may feel you were awake during the procedure the drugs often prevent you from remembering much of the investigation.

You will also be attached to a monitor by putting a small probe on your finger. This will tell the doctor what your pulse and oxygen levels are.
The doctor will start off by performing a rectal examination, putting a lubricated gloved finger into your back passage. The lubricated colonoscope will then be gently inserted.

As the scope gently moves around your colon you may feel as though you need to have your bowels open. This is a sensation caused by the scope and the air used as it advances. As air is introduced you may feel some cramping or fullness in your abdomen. This will be relieved once the air is removed.

The light and camera on the tip of the colonoscope will relay the pictures of your colon onto a TV screen. You are invited to watch the procedure, otherwise you are advised not to look at the screen if you are squeamish.

The procedure will take 20 â€" 30 minutes depending on the success of the bowel preparation and whether any polyps need to be removed or biopsies taken (tissue samples).  

After the procedure

Once the procedure is complete you will be wheeled back to the recovery room. Here the nurse will monitor your blood pressure for a short time. Once you are fully awake you will sit up and be offered some refreshments.

You may find that your abdomen feels bloated and that you need to go to the toilet to pass wind. This is not unusual and moving around often helps pass the wind quicker.

Before you go home the nurse or doctor will check that you have recovered and tell you about the investigation. Any follow up appointments will be made for you.

As you have received sedation you MUST organise for a responsible adult to drive you home and be available for the next 24 hours. It is advised that you rest for the remainder of the day and drink plenty of fluids and eat as you wish. Because of this medication you will not be able to drive, have alcohol or operate machinery for the next 24 hours.
If the doctor took any biopsies or removed any polyps you will possibly notice small amounts of blood over the next few days when you have your bowels open. This is nothing to be concerned about.

If at home you experience any of the following you must seek medical care immediately:

-  Passing of large amounts of fresh blood from your back passage
-  Vomiting and sharp pains in your abdomen
-  Feeling faint or short of breath

What are the risks?

If the doctor needs to remove a polyp or take a biopsy there is a risk that a haemorrhage (heavy bleeding) may occur. It may be necessary for you to have a blood transfusion or to reinsert the colonoscope to control the bleeding.

Another small risk when introducing the tube, removing polyps, or taking a biopsy is perforation. This is a puncture (small hole) made in the bowel wall, which will require surgical repair.

Be sure to discuss any concerns you have with the doctor before the procedure.

When do I know the result?

In many cases the doctor will be able to tell you the results of the test as soon as you are awake. However, if a sample (biopsy) has been taken or polyps have been removed for examination, the results may take several days.