Lower GI Tract Radiography (x-ray, Barium Enema )

How should I prepare for the procedure?

You should tell your doctor about any recent illnesses or other medical conditions, as well as any allergies you might have to medications. Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant.

Your doctor will give you detailed instructions on how to prepare for your lower GI imaging. During the day before the procedure, you will likely be asked not to eat, and to drink only clear liquids like juice, tea, black coffee, cola, or broth, and avoid dairy products. After midnight, you should take nothing by mouth. You may also be instructed to take a laxative (in either pill or liquid form) and to use an over-the-counter enema preparation the evening, or even a few hours before the procedure. Just follow your doctor's instructions. It is permissible to take usual prescribed oral medication with limited amounts of water.

Once you arrive at the imaging center, you will be asked to change into a gown before your examination. You may also be asked to remove jewelry, eyeglasses, or any metal objects that could obscure the images.

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How does the procedure work?

Very small, physician-controlled amounts of x-ray radiation are passed through the body. Different tissues—such as bone, blood vessels, muscles, and other soft tissues—absorb x-ray radiation at different rates. When a special film plate is exposed to the absorbed x-rays, a detailed image of the inside of the abdomen is captured.

The tissues of the lower GI tract are similar in density, so a contrast material is needed to provide exquisite detail of the inside of the colon. Liquid barium, a dense, non-absorbable metallic solution, is introduced into the colon through a rectal tube. The barium coats the inside of the rectum, colon, and a part of the lower small intestine, and produces a sharp, well-defined image.

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How is the procedure performed?

A lower GI radiological examination is often done on an outpatient basis. The radiologist or technologist will discuss details of the examination and can review rare contraindications (circumstances that need special consideration). The patient is positioned on the table, and a preliminary film is obtained to check for adequacy of the bowel preparation. The radiologist or technologist will then make the contrast material introduction through a small tube inserted into the rectum. A mixture of barium and water is passed into the patient's colon through the tube. To help the barium thoroughly coat the lining of the colon, air may also be injected through the tube. In some circumstances, the radiologist or referring physician may prefer a water and iodine solution rather than barium to opacify the colon. Then a series of images is captured.

The patient may be repositioned frequently to enable the radiologist or technologist to capture views of their colon from several angles. Some equipment allows patients to remain in the same position throughout the exam. During the study, the radiologist will monitor the delivery of barium and take or request special views or close-ups.

Once the x-ray images are completed, most of the barium is drawn back into a bag, and the patient is directed to the washroom to expel the remaining barium and air. In some cases, the technologist may then take additional images to help the doctor see how well the colon has cleared. The patient is then released.

A lower GI study typically takes 30 to 60 minutes.

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What will I experience during the procedure?

As the barium fills your colon, you will feel the need to move your bowel. You may feel abdominal pressure, or even minor cramping. These are common sensations, and most people tolerate the mild discomfort easily. The tip of the enema tube is specially designed to help you hold in the barium. If you are having trouble, let the technologist know.

During the imaging process, you will be asked to turn from side to side, and to hold several different positions. At times, pressure may be applied to your abdomen. With air contrast studies of the bowel, the table may be turned into an upright position.

You are able to return to a normal diet and activities immediately after the exam. Your stools may appear white for a day or so, as your body clears the metallic liquid from your system. You will be encouraged to drink additional water for 24 hours after the examination. After a barium enema, some people experience constipation. If you do not have a bowel movement for more than two days after your exam, or are unable to pass gas rectally, call your doctor promptly. You may need an enema or laxative to assist in eliminating the barium, and your doctor will prescribe the right solution for you.

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What are the benefits vs. risks?

Benefits

With the use of the barium contrast material, lower GI imaging provides valuable, detailed information to assist physicians in diagnosing and treating conditions from normal to ulcers to cancer.

X-ray imaging of the lower GI tract is a minimally invasive procedure with rare complications.

You may return to normal activity following the examination.

The imaging process is fast and well-tolerated.

Radiology examination can often provide enough information to avoid more invasive procedures, such as colonoscopy.

Risks

In rare cases, the barium suspension could leak through an undetected perforation in the lower GI tract, producing inflammation in surrounding tissues.

Even more rarely, the barium can cause an obstruction in the gastrointestinal tract, called barium impaction.

The effective radiation dose from this procedure is about 4 mSv, which is about the same as the average person receives from background radiation in 16 months. See the Safety page for more information about radiation dose.

Women should always inform their doctor or x-ray technologist if there is any possibility that they are pregnant.

Radiation risks are further minimized by:

Special care that is taken during x-ray examinations to ensure maximum safety for the patient by prudent, targeted application of fluoroscopic radiation.

The use of high-speed x-ray film that does not require much radiation to produce an optimal image.

Technique standards established by national and international guidelines that have been designed and are continually reviewed by national and international radiology protection councils.

Modern, state-of-the-art x-ray systems (including mammography systems, angiographic labs and CT scanners) that have very tightly controlled x-ray beams with significant filtration and x-ray dose control methods. Thus, scatter or stray radiation is minimized and those parts of a patient's body not being imaged receive minimal exposure.

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What are the limitations of Lower GI Tract Radiography?

A barium enema is usually not indicated for someone who is in extreme abdominal pain or had a recent colonic biopsy. If perforation is suspected, the enema should be performed with the iodinated solution. X-ray imaging is not usually indicated for pregnant women.

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To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.

This procedure is reviewed by a physician with expertise in the area presented and is further reviewed by committees from the American College of Radiology (ACR) and the Radiological Society of North America (RSNA), comprising physicians with expertise in several radiologic areas.