Colonoscopy

A colonoscopy allows a doctor to look inside the entire large intestine, which is also called the colon. The procedure enables the physician to see things such as inflamed tissue, abnormal growths and ulcers. It is most often used to look for early signs of cancer in the colon and rectum. (Read about "Colorectal Cancer") It is also used to look for causes of unexplained changes in bowel habits and to evaluate symptoms like abdominal pain, rectal bleeding and weight loss. (Read about "Gastrointestinal Bleeding")

The colon, or large intestine, is the last portion of your digestive or gastrointestinal tract. (Read about "Digestive System") The colon is a hollow tube that starts at the end of the small intestine and ends at the rectum and anus. The colon is about 5 feet long, and its main function is to store unabsorbed food waste and absorb water and other body fluids before the waste is eliminated as stool.

There are things you must do to prepare for a colonoscopy. Your colon must be completely empty for the colonoscopy to be thorough and safe. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says to prepare for the procedure you will have to follow a liquid diet for 1 to 3 days beforehand. The liquid diet should be clear and not contain food colorings, and may include:

• fat-free bouillon or broth
• strained fruit juice, no purple or red grape juice
• water
• plain coffee
• plain tea
• diet soda
• gelatin, not purple or red

Thorough cleansing of the bowel is necessary before a colonoscopy. You will likely be asked to take a laxative the day before the procedure, and possibly on the day of the procedure. In some cases, you may also have an enema. The American College of Gastroenterology (ACG) says it is important to let your doctor know of any medical conditions you have or medications you take on a regular basis such as:

• aspirin
• arthritis medications (Read about "Arthritis & Rheumatic Diseases")
• blood thinners
• diabetes medication (Read about "Diabetes")
• vitamins that contain iron (Read about "Vitamins & Minerals")

The staff where you have the procedure will also want to know if you have heart disease, lung disease or any medical condition that may need special attention. (Read about "Coronary Heart Disease" "Respiratory System")

In a traditional colonoscopy, you will also need to arrange for someone to take you home afterward, because you will not be allowed to drive after being sedated. For the colonoscopy, you will lie on your side on the examining table. You will be given pain medication and a moderate sedative to keep you comfortable and help you relax during the exam. (Read about "Anesthesia") ACG says the doctor and a nurse will monitor your vital signs, look for any signs of discomfort and make adjustments as needed.

The doctor will then insert a long, flexible, lighted tube into your rectum and slowly guide it into your colon. The tube is called a colonoscope. The scope transmits an image of the inside of the colon onto a video screen so the doctor can carefully examine the lining of the colon. The scope bends so the doctor can move it around the curves of your colon.

You may be asked to change positions at times so the doctor can more easily move the scope to see better the different parts of your colon. The scope blows air into your colon and inflates it, which helps give the doctor a better view. Most patients do not remember the procedure afterwards, according to NIDDK.

The doctor can remove most abnormal growths in your colon, like a polyp, which is a growth in the lining of the bowel. (Read about "Colon Polyps") Polyps are removed using tiny tools passed through the scope. Most polyps are not cancerous, but they could turn into cancer. (Read about "Cancer: What It Is") Just looking at a polyp is not enough to tell if it is cancerous. The polyps are sent to a lab for testing. (Read about "Laboratory Testing") By identifying and removing polyps, a colonoscopy likely prevents most cancers from forming.

The doctor can also perform a biopsy. (Read about "Biopsy") That is the removal of tissue samples to test in the lab for diseases of the colon. In addition, if any bleeding occurs in the colon, the doctor can pass a laser, heater probe, electrical probe or special medicines through the scope to stop the bleeding. The tissue removal and treatments to stop bleeding usually do not cause pain. In many cases, a colonoscopy allows for accurate diagnosis and treatment of colon abnormalities without the need for a major operation, according to ACG.

During the procedure, you may feel mild cramping. NIDDK says you can reduce the cramping by taking several slow, deep breaths. When the doctor has finished, the colonoscope is slowly withdrawn while the lining of your bowel is carefully examined. NIDDK says bleeding and puncture of the colon are possible but uncommon complications of a colonoscopy.

Expect to be in the examination area for 30 to 60 minutes. The actual exam of the colon will take less time than that. The sedative and pain medicine should keep you from feeling much discomfort during the exam. You may feel some cramping or the sensation of having gas after the procedure is completed, but it usually stops within an hour. You will need to remain at the colonoscopy facility for 1 to 2 hours so the sedative can wear off.

Rarely, some people experience severe abdominal pain, fever, bloody bowel movements, dizziness or weakness afterward. If you have any of these side effects, contact your physician immediately. Read your discharge instructions carefully. Medications such as blood-thinners may need to be stopped for a short time after having your colonoscopy, especially if a biopsy was performed or polyps were removed. Do not however make that decision yourself without discussing all of the issues with your doctors. NIDDK says full recovery by the next day is normal and expected and you may return to your regular activities.

In addition to traditional colonoscopy, there is also a procedure called virtual colonoscopy (VC). VC uses x-rays (Read about "X-rays") and computers to produce two- and three-dimensional images of the colon from the lowest part, the rectum, all the way to the lower end of the small intestine and display them on a screen. Virtual colonoscopy is also called CT colonography. (Read about "CT Scan - Computerized Tomography") Magnetic resonance imaging (MRI) technology can also be used. (Read about "MRI - Magnetic Resonance Imaging")

While preparations for VC vary, you will usually be asked to take laxatives or other oral agents at home the day before the procedure to clear stool from your colon. You may also be asked to use a suppository to cleanse your rectum of any remaining fecal matter.

VC takes place in the radiology department of a hospital, medical center or in specialized centers. The examination takes about 10 minutes and does not require sedatives. After the examination, the information from the scanner must be processed to create the computer picture or image of your colon. A radiologist evaluates the results to identify any abnormalities.

You should discus the advantages and disadvantages of both virtual and traditional colonoscopy with your doctor.

Related Information:

    Flexible Sigmoidoscopy