Edinburgh Gastroenterology
...tradition at the leading edge
Tradition at the leading edge, from Edinburgh Gastroenterologists

Information on Gastrointestinal Investigations

Understanding Colonoscopy

What is a colonoscopy?

Colonoscopy enables your doctor to examine the lining of your colon (large intestine, bowel) for abnormalities by inserting a flexible telescope through the back passage and slowly advancing it around the colon. If your doctor has recommended a colonoscopy, this information will give you a basic understanding of the procedure - how it's performed, how it can help, and what side effects you might experience. It can't answer all of your questions since much depends on the individual patient and the doctor. Please ask your doctor about anything you don't understand.

What preparation is required?

Your doctor will tell you what bowel preparation to use. In general, the preparation consists of either consuming a large volume of a special cleansing solution or clear liquids and special oral laxatives. The colon must be completely clean for the procedure to be accurate and complete, so be sure to follow the instructions carefully.

Can I take my current medications?

Most medications can be continued as usual, but some medications can interfere with the preparation or the examination. Inform your doctor about medications you're taking, particularly blood-thinning drugs such as aspirin, clopidogrel, warfarin or heparin, arthritis medications, insulin or iron tablets. Also, be sure to mention allergies you have to medications.

Alert your doctor if you require antibiotics prior to dental procedures, because you might need antibiotics before a colonoscopy as well.

What happens during colonoscopy?

Colonoscopy is generally well-tolerated and rarely causes more than mild discomfort. You might feel pressure, bloating or cramping during the procedure. In most cases a sedative and/or a pain medication is given prior to the procedure to help you relax and better tolerate any discomfort.

You will lie on your side or back while the doctor slowly advances a colonoscope through your colon to examine the lining. The colon is examined further as the colonoscope is withdrawn. The procedure itself usually takes 20 to 30 minutes, although you should plan on two to three hours in the unit for preparation and recovery.

In a small proportion of cases, the colonoscope cannot be passed through the entire colon to where it meets the small intestine. If this is the case a further examination, usually a CT scan, might be needed, unless it is considered that the limited examination is sufficient.

What if the colonoscopy shows something abnormal?

If an area of the colon needs further evaluation, an instrument can be passed through the colonoscope to obtain a biopsy (a sample of the colon lining) for analysis. Biopsies are used to identify many conditions, and do not necessarily mean that anything sinister is suspected. If colonoscopy is being performed to identify a source of bleeding, this may be treated by coagulation (sealing off bleeding vessels with heat treatment). Your doctor might also find polyps during colonoscopy, and will most likely remove them during the examination. These procedures don't usually cause any pain.

What are polyps and why are they removed?

Polyps are abnormal growths in the colon lining that are usually benign (non-cancerous). They vary in size from a tiny dot to several inches. It is not always possible to tell the type of polyp by its appearance, so polyps that are removed are usually sent for analysis. Most polyps are benign, but because cancer can begin in polyps, removing them is an important means of preventing colorectal cancer.

How are polyps removed?

Your doctor might destroy tiny polyps by heat treatment or by removing them with instruments passed through the colonoscope. Larger polyps are removed using a technique called "snare polypectomy" which involves passing a wire loop through the colonoscope and removing the polyp from the intestinal wall using an electrical current. Polypectomy is normally painless.

What happens after a colonoscopy?

Your doctor will explain the results of the examination to you, although although if there are biopsies or polyps removed the results of these will not be available for a week or two.

If you have been given sedatives during the procedure, someone must drive you home and stay with you. Even if you feel alert after the procedure, your judgment and reflexes could be impaired for the rest of the day. You may have some cramping or bloating because of the air introduced into the colon during the examination. This should disappear quickly when you pass gas.

What are the possible complications of colonoscopy?

Although complications can occur, they are rare when doctors who are specially trained and experienced in this procedure perform the test.

Bleeding can occur at the site of biopsy or polypectomy, but it's usually minor. Bleeding usually stops on its own, or can be controlled through the colonoscope; it rarely requires follow-up treatment. A perforation, or tear, through the bowel wall that could require surgery is a rare but serious complication of colonoscopy. Some patients can have a reaction to the sedative drugs given, or complications relating to heart or lung disease.

Although complications after colonoscopy are uncommon, it's important to recognize early signs of possible complications. Make contact immediately if you notice severe abdominal pain, fever and chills, or bleeding from the back passage of more than half a cup. Note that bleeding can sometimes be delayed until several days after the procedure.


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