by Rosalyn Carson-DeWitt, MD
Anatomy and Physiology
The digestive tract consists of the mouth, the esophagus, the stomach, the small intestine, the large intestine or colon, and the rectum. Food travels down the digestive tract in this order.
The main function of the colon is to absorb water into the body, change liquid waste material into solid waste material known as feces, and store feces until enough accumulates to be passed from the anus as a bowel movement.
Reasons for Procedure
A barium enema is an x-ray examination of your colon. Barium is a chalky substance that is put into your colon before the x-rays are taken. The barium coats the inside of your colon, so that a camera can take images of the lining, or mucosa.
Your doctor may recommend that you get a barium enema to check for abnormalities in the colon, such as: colon cancer, polyps, which could develop into colon cancer, outpouchings of the colon wall, called diverticula, ulcers or narrowed areas known as strictures, which may indicate inflammatory bowel disease, other possible causes for unexplained bleeding or a change in bowel habits.
Abnormalities detected by barium enema are often further evaluated by colonoscopy. In a colonoscopy, a lighted fiberoptic tube equipped with a camera is introduced through the rectum and into the colon. This allows the doctor to directly view the tissues and take biopsy samples. A colonoscopy looks at the entire length of the colon.
Another common diagnostic test is a sigmoidoscopy, which is similar to a colonoscopy, but only reaches half way into the colon.
A newer diagnostic test is called virtual colonoscopy. This test uses a CT scan and a computer to create a 3D reconstruction of the colon.
In order to be able to clearly visualize your colon on an x-ray, it must be as empty as possible. In the days leading up to your procedure, your doctor will give you specific directions on emptying your colon. These may include: starting a clear liquid diet a day or two prior to the exam; taking laxatives and/or enemas to clear feces out of the colon.
When you arrive at the examination, you'll be asked to undress and lie down on an x-ray table. A lubricated tube will be carefully inserted into your rectum. A bag containing barium will be attached to the tube, and the barium will be allowed to flow into your colon.
When enough barium has flowed into your colon, you'll be asked to try very hard not to expel any of it while x-rays are taken. A tiny balloon attached to the tubing that carries the barium may be inflated to prevent any barium from leaking out during the exam.
While the x-ray pictures are being taken, you'll be asked to roll from side-to-side, or to stand up. This lets the barium flow to different areas so that sufficient x-ray images can be obtained of your entire colon.
After many x-ray pictures are taken, you will be given a bedpan or taken to a bathroom and asked to expel as much of the barium as possible. A few more x-rays may be taken after you have passed most of the barium out of your colon.
In a double-contrast barium enema, air will then be introduced into your colon through a tube in your rectum. The air stretches the colon wall and forces the barium against the surface mucosa for more detailed images. This is a more sensitive way to look for lesions of the colonic mucosa and is the test your doctor will likely order.
Risks and Benefits
Although most barium enemas are successfully completed without complications, the potential risks of the procedure include: dizziness during the course of the exam, infection, accidental tearing, called perforation, of your intestine or rectum, intestinal blockage caused by barium remaining in your colon.
Benefits of barium enema include the following: early detection of colon cancer or relatively large polyps, although it's less sensitive than colonoscopy for this purpose, it is less invasive than colonoscopy, which is somewhat riskier and requires sedation.
In a barium enema, or any procedure, you and your doctor must carefully weigh the risks and benefits to determine whether it's the most appropriate procedure for you.
After the Procedure
After your barium enema, you can go home. You won't need to take any special precautions, and will most likely be able to resume your normal diet. Most radiologists instruct patients to increase their fluid intake for a period of time to be certain all of the barium is passed. You will likely notice more gas than usual, and see barium in the next several bowel movements that you pass.
Once at home, be sure to contact your doctor if you experience: fever or chills, abdominal or rectal pain, weakness, severe nausea or vomiting, difficulty passing a bowel movement, blood in your stools that was never there before, light-colored stools days after the exam, and/or pencil-thin stools.
- American College of Gastroenterology, accessed at http://www.acg.gi.org/index.html. Accessed September 21, 2004.
- "Barium enema: Viewing the colon for abnormalities," accessed at Mayo clinic website, http://www.mayoclinic.com/invoke.cfm?id=SA00003. Accessed September 21, 2004.
- "Intussusception," accessed at the website of the American Academy of Family Physicians, http://familydoctor.org/x1730.xml. Accessed September 21, 2004.
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