Colonoscopy is usually the preferred test to examine the digestive tract. However, there are several commonly performed X-ray tests that allow your doctor to examine your digestive tract from the esophagus to the rectum.
These tests utilize barium or an iodine-containing agent that allows visualization of the digestive tract and a form of X-ray machine called fluoroscopy. Fluoroscopy allows part of the body to be studied in motion and recorded on a video monitor.
Fluoroscopic examinations of your GI tract may be performed in a doctor's office, a commercial X-ray facility, or a hospital. These tests are called an "upper GI" or "lower GI," depending on the organs being examined.
Upper GI Tests
Upper GI tests use X-rays to examine the esophagus, stomach, and first part of the small intestine (the duodenum).
For these tests, you need to drink barium. As the barium passes through the digestive tract, it fills and coats the esophagus, stomach, and first part of the small intestine, making them more visible with X-ray. Then a fluoroscope machine is held over the part of the body being examined and transmits continuous images to a video monitor.
This upper GI test is used to diagnose:
- Hiatal hernias
- Esophageal varices
- Obstruction or narrowing of the upper GI tract
It may also be used to determine the cause of:
- Swallowing problems
- Reflux symptoms (dyspepsia or heartburn)
- Abdominal pain
- Unexplained vomiting, weight loss, or bleeding
There are several types of tests used to view the upper GI tract, including:
- Barium swallow. This is an X-ray test that examines how food moves down the esophagus to the stomach. Approximate time: 30 minutes.
- Modified barium swallow. This test looks at the beginning of swallowing from the mouth to the pharynx and down to the esophagus. Approximate time: 30 minutes to 1 hour.
- Upper GI series. This is an X-ray examination of the esophagus, stomach, and upper part of the small intestine. Approximate time: 30-45 minutes.
- Small bowel series. This is an X-ray examination of the small intestine (small bowel). Approximate time: 2 to 4 hours, depending upon how long it takes for the barium to reach the colon.
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:
- Colon polyps
- Diverticular disease
- Strictures or sites of narrowing and obstruction
- Ulcerative colitis or Crohn's disease
- Other causes of abdominal pain or blood, mucus, or pus in the stool
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.
What Happens During the GI Tests
During GI testing:
- You will be positioned on a tilting X-ray table by the technologist. For an upper GI test, the table usually starts in a vertical position, with the person standing. For a lower GI test, the table usually starts in a horizontal position, with the person lying on his or her back or stomach. The table will be tilted at various angles during the test to help spread the barium solution throughout the body so that different views can be seen on the fluoroscope. During the test, the radiologist may put pressure on your abdomen to get a clearer image on the fluoroscope.
- Although the barium solution given in an upper GI test is unpleasant tasting, there is no pain and little discomfort during the procedure. The lower GI test may cause some discomfort, including cramps and a strong urge to have a bowel movement.
- After the barium enema is administered in a lower GI test and a few X-rays are taken, you will be helped to the bathroom (or given a bedpan) and asked to move your bowels to expel as much of the barium as possible. Then you will go back to the X-ray examination room where more X-rays will be taken of the barium solution that remains on the lining of the intestine. In some cases, air will be injected slowly into the colon (air contrast barium enema) to provide further contrast on the X-rays to detect abnormalities.
After the GI Tests
Generally, you can resume your usual activities and normal diet immediately after your GI tests. Unless fluid is restricted by your doctor for another medical condition, drink plenty of water or juice -- 8-10 glasses each day for three days -- to eliminate the barium from your colon.
It is normal for your stool to have a white or light color for up to three days after the test, and the barium enema given during a lower GI test may leave you feeling weak or dizzy.
The Risks of GI Tests
There is virtually no risk with the upper and lower GI tests, unless they are repeated several times within a few months' time, when radiation exposure can become a risk. Although radiation exposure is minimal, it is greater than for standard still X-rays. Steps will be taken during the test to minimize radiation exposure.
Other risks include:
- Infection (very low risk with both the upper and lower GI tests)
- Tearing the intestinal wall during a lower GI test; should this occur, surgery may be necessary. This is a very rare complication.
Cases Where GI Tests Should Not Be Performed
If you have an existing blockage or tear in the intestinal wall, the upper and lower GI tests should not be performed.
If you are pregnant or think you might be pregnant, you should not have these tests unless absolutely medically necessary. Talk to your doctor about other tests that can be more safely performed to diagnose your problem during pregnancy.
When to Call Your Doctor After GI Tests
After the GI tests, call your doctor if you have:
- A temperature of 101 degrees Fahrenheit or higher. This could be a sign of infection and should be treated right away.
- A marked change in bowel habits (such as no bowel movement in two or three days after the test); remember, it is normal for your stool to have a white or light color for up to three days after the test.
- Worsening of pain
- Any unusual rectal drainage
- Other symptoms that cause concern
- Questions about the test or the results