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Colonoscopy

Colonoscopy is a common and very safe procedure that examines the lining of your lower intestinal tract called the colon or large intestine. Colonoscopy means "to look inside the colon."

A doctor specially trained in the procedure uses a flexible tube that has a light and miniature TV camera on the tip. This instrument, often referred to as the "scope," is placed in the rectum and advanced through the colon. It is connected to a television monitor that your doctor watches while performing the test. Various miniaturized tools can be inserted through the scope to help your doctor obtain biopsies (samples) of the colon and to perform a wide range of maneuvers to help diagnose or treat your condition.

When used as a colon cancer prevention method, colonoscopy can find potentially precancerous growths called polyps and remove them before they turn into cancer. This explains why colonoscopy is an invaluable tool that helps your doctor answer important questions about your digestive health and prevent certain diseases like colon cancer.

Colonoscopy: What Patients Can Expect Before, During and After a Procedure

Questions to ask your MD

Colonoscopy Common Questions


Why is colonoscopy performed?
Colonoscopy is used to directly see the lining of the colon to look for conditions such as cancer, colitis (inflammation of the colon) and diverticular disease (small pockets on the colon). Colonoscopy may also be used to investigate unexplained diarrhea, bleeding and anemia. Sometimes colonoscopy is used to evaluate an abnormality seen on other imaging tests such as CT scans and barium studies.

What preparation is required?
Your doctor will tell you what sort of diet and cleansing routine to follow before the test. Your cooperation in this preparation will allow the gastroenterologist to get the clearest and most accurate views possible. In general, the "prep" involves drinking a special cleansing solution, along with plenty of clear fluids, and taking special laxatives by mouth. Be sure to tell your doctor about conditions such as diabetes, heart and/or kidney disease. You should plan your prep diet ahead of time and check with your doctor if you have any questions.

Can I take my regular medications?
Most medications can continue to be taken as directed, but some can interfere with the preparation or the examination. You should tell your doctor about all your medications, especially aspirin products, anti-inflammatory medications such as ibuprofen, pain medicines, blood thinners, insulin or iron supplements. Don't forget to mention "over the counter" supplements that you may be taking as well. You should also tell your doctor if you normally require antibiotics before dental procedures, since you may have the same needs before your colonoscopy.

Is colonoscopy painful?
A colonoscopy is a very comfortable exam because it is usually done with intravenous sedation. This means that you will be in a very sleepy state during the procedure. Most patients are not even aware that the procedure happened when they wake up.

What happens during a colonoscopy?
Most doctors perform colonoscopy in a procedure room with a TV monitor. After your medical history has been reviewed and the medical staff has explained the procedure and answered any questions you may have, you will sign a permission form.

You will then be connected to equipment that monitors your heart rate, blood pressure and oxygen levels. Before the procedure, an IV will be started in your arm so that sedatives and other medications can be administered.

You will lie on your side or back and once sedated, your doctor slowly advances the scope through your colon. Air is pumped into the colon to allow expansion for a careful examination of the lining. Water may also be used to wash any fecal residue. There is also a suction device attached to the scope to remove any remaining fluid from the prep.

The scope is slowly and carefully advanced around the colon to the point where the large intestine joins the small intestine in the right lower region of the abdomen, near the appendix. If polyps are found they are removed. Any abnormal tissue is biopsied. The procedure usually takes 20 to 60 minutes, although you should plan on being in the endoscopy unit for a total of two to three hours to account for preparation, procedure and recovery.

What happens if the colonoscopy shows something abnormal?
One of the main advantages of colonoscopy over other types of tests is its ability to sample abnormal areas of the colon for further evaluation. Sometimes your doctor will take biopsies in areas that look normal to the naked eye. If you are having a colonoscopy because of internal bleeding, your doctor may decide to cauterize or clip the bleeding vessels with special instruments passed through the scope. Such procedures rarely cause any pain. If a polyp is found, it is removed and then sent to the pathology lab for microscopic evaluation.

Why is polyp removal (polypectomy) performed if found during the colonoscopy?
One of the most common uses of colonoscopy is for screening and prevention of colon cancer. Finding a potentially precancerous polyp is important as most cancers can be prevented by removing the polyp before it has a chance to become cancerous. Polyps vary in size from about the size of a pea to several inches and are usually harmless. However, some polyps can become cancerous and for this reason, they are usually removed during the colonoscopy. This procedure is called a "polypectomy." In most cases, your doctor cannot tell which polyps may eventually become cancerous, so the whole polyp, or at least a sample of it, needs to be examined under a microscope. The ability to safely and painlessly remove such growths before they become cancerous has made colon cancer one of the most preventable cancers in the world.

What happens after a colonoscopy?
Your physician will explain the results of the examination, but you will probably have to wait for the results of any biopsies. If you received sedatives during the exam, you will need to have a friend or relative take you home. Even if you feel alert after the procedure, your judgment and reflexes could be impaired for the rest of the day. Because your doctor used air to inflate the colon when looking at the lining of the colon, you might experience some cramping or bloating. This feeling should disappear once you start passing gas. Although you should be able to eat shortly after the examination, your doctor might restrict your diet and activities if a procedure, such as removing a polyp, was performed.

What are the possible complications or risks of colonoscopy?
Colonoscopy and the special techniques mentioned above are very safe when performed by specially trained doctors with experience performing these types of procedures. As with any medical procedure, even in expert hands, unintended events may happen and you need to be aware of the potential consequences.

There is a small risk of having a reaction to any of the drugs given during the exam. In most cases, medications are available to counteract these side effects. A rare complication is tearing or perforation of the lining of the intestine. Should this occur, surgery may be needed to seal the injury. Another risk is bleeding, usually at the site of a biopsy or polyp removal. Most cases of bleeding stop without treatment or can be controlled at the time of procedure.

What sort of things should concern me after the colonoscopy?
Although complications after colonoscopy are uncommon, it is important to be aware of early signs that something is wrong. You should not hesitate to contact your doctor up to two weeks after the colonoscopy if you feel abdominal pain, dizziness, fever/chills, or notice blood in your stools.

Colonoscopy Alternatives
There are a number of ways to examine the colon and each method has its advantages and disadvantages. In the past, X-rays were combined with a special dye inserted through the anus (barium enema) as the standard test to look for abnormalities inside the colon. This method is still sometimes used (usually when a complete colonoscopy is not possible), but has largely been replaced by direct examination of the colon by colonoscopy. Colonoscopy is the only approach that provides a precise diagnosis by taking a biopsy and reduces the risk of colon cancer by removing polyps. Other tests such as virtual colonoscopy (or CT colonography, a type of CT scan) are being evaluated for select situations. Experts have not established guidelines for the use of tests like virtual colonoscopy and abnormal results often still require clarification with a standard colonoscopy.

For questions about this Web site, contact info@asge.org. For questions specifically related to your health and getting screened for colorectal cancer, contact your doctor, or to find a doctor in your area.