A barium enema, or lower gastrointestinal (GI) examination, is an X-ray examination of the large intestine (colon and rectum). The test is used to help diagnose diseases and other problems that affect the large intestine. To make the intestine visible on an X-ray picture, the colon is filled with a contrast material containing barium. This is done by pouring the contrast material through a tube inserted into the anus. The barium blocks X-rays, causing the barium-filled colon to show up clearly on the X-ray picture.

There are two types of barium enemas.

• In a single-contrast study, the colon is filled with barium, which outlines the intestine and reveals large abnormalities.
• In a double-contrast or air-contrast study, the colon is first filled with barium and then the barium is drained out, leaving only a thin layer of barium on the wall of the colon. The colon is then filled with air. This provides a detailed view of the inner surface of the colon, making it easier to see colon polyps, colorectal cancer, or inflammation.

In some cases, the single-contrast study may be preferred for specific medical reasons or for older people who may not be able to tolerate the time-consuming and somewhat more uncomfortable double-contrast study. However, if the results are not clear or there is a strong suspicion of colorectal cancer, a double-contrast study may also be done.

Why It Is Done

A barium enema is done to:

• Screen for colon polyps or colon cancer. Most medical experts recommend colon cancer screening beginning at age 50 for people who do not have an increased risk of colon cancer. Earlier screening is recommended for people who have an increased risk of colon cancer, such as those with a family history of colon cancer.
• Identify inflammation of the intestinal wall that occurs in inflammatory bowel diseases, such as ulcerative colitis or Crohn's disease. A barium enema also may be used to monitor the progress of these diseases.
• Detect problems with the structure of the large intestine, such as narrowed areas (strictures) or pockets or sacs (diverticula) in the intestinal wall.
• Help correct a condition called ileocolic intussusception, in which the end of a child's small intestine protrudes into the large intestine.
• Evaluate abdominal symptoms such as altered bowel habits, anemia, or unexplained weight loss.

How To Prepare

Before a barium enema, tell your health professional if you:

• Are or might be pregnant.
• Are allergic to latex. Latex products are commonly used to administer the contrast material. If you have a latex allergy, different products will be used.
• Know that you are allergic to barium.
• Have had an upper digestive barium test (upper GI or barium swallow) recently.

The preparation for a barium enema usually involves a very thorough cleansing of the large intestine, because the colon must be completely clear of stool and gas. Even a small amount of stool can affect the accuracy of the test.

• For 1 to 3 days before the test, you will usually be on a clear liquid diet.
• On the day before the test:
  • You should drink very large amounts of noncarbonated clear liquids, unless your health professional has advised you not to.
  • You will then take a combination of laxatives (such as castor oil, magnesium citrate, or bisacodyl) to empty your intestines.
  • You may be asked to take a tap water enema to clean any remaining stool from your colon.
• On the day of the test, you may need to repeat the enema until the liquid that passes is free of any stool particles. Sometimes a rectal suppository or a commercially prepared enema, such as a Fleet enema, is used instead of a tap water enema.

Talk to your health professional about any concerns you have regarding the need for this test, its risks, how it will be done, or what the results will indicate. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?) .