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Crohn's Disease Health Center

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X-Ray Exams of the Digestive Tract

Lower GI Tests

Lower GI tests or barium enemas are used to examine the large intestine and the rectum. For this test, barium or an iodine-containing liquid is introduced gradually into the colon through a tube inserted into the rectum. As the barium passes through the lower intestines, it fills the colon, allowing the radiologist to see growths or polyps and areas that are narrowed. The fluoroscope is held over the part of the body being examined and transmits continuous images to the video monitor.

This lower GI testing is used to detect:

There are several types of tests used to view the lower GI, including:

  • Air contrast barium enema (double contrast barium enema). This is an X-ray examination of the large intestine (colon). Barium and air are introduced gradually into the colon by a rectal tube. Approximate time: 1 hour.
  • Barium enema. This is an X-ray examination of the large intestine (colon). Barium is introduced gradually into the colon by a rectal tube. Approximate time: 1 hour.

With the barium or contrast enema, the colon is filled with a contrast material containing barium or iodine-containing contrast (a liquid that lights up on X-ray) by running it through a tube inserted into the rectum. The colon, when filled with the agent, shows up clearly on the X-ray picture.

The air contrast study is slightly different. The colon is first filled with some barium, followed by air. This technique provides a more detailed picture of the lining of the colon, improving the procedure's ability to detect small polyps or inflammation.

Preparing for Upper and Lower GI Exams

Preparation for upper GI or lower GI testing usually includes following a low-fiber diet for two to three days before the test, not smoking for 12 to 24 hours before the test, not taking any medications for up to 24 hours before the test, and not eating anything for 12 hours before the test. Your doctor will give you specific instructions. Never stop taking any medications without first discussing it with your doctor.

Additional preparation for the lower GI test usually includes taking oral laxatives and an enema the night before the test. Carefully follow the pre-test directions given to you by your doctor.

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