Test Overview
Why It Is Done
How to Prepare
How It Is Done
How It Feels
Risks
Results
What Affects the Test
What to Think About
Credits
Barium Enema
Test Overview
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 (hence the name barium enema). 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 enema.
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 much more detailed view of the inner surface of the colon, making it easier to see small polyps, tumors, 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 if there is a strong suspicion of colon cancer, a double-contrast study may also be done.
Why It Is Done
A barium enema is done to:
Screen for colon polyps or cancer. Medical experts disagree about routine screening for colorectal cancer.
Most experts, including the American Gastroenterological Association, recommend colon cancer screening beginning at age 50 for people at average risk for colon cancer. Fecal occult blood testing (FOBT) combined with flexible sigmoidoscopy testing often is recommended, but colonoscopy or double-contrast barium enema (DCBE) may be used. If results from FOBT, DCBE, or sigmoidoscopy are abnormal, a follow-up colonoscopy or flexible sigmoidoscopy combined with DCBE is recommended. For more information, see the medical tests Fecal Occult Blood Test, Colonoscopy, and Sigmoidoscopy.
The American Gastroenterological Association recommends that people at increased risk for colon cancer begin screening at age 40. Depending on your risk level, screening may include FOBT, sigmoidoscopy, double contrast-barium enema, or colonoscopy. If you are at increased risk of colon cancer, talk to your doctor about which test is best for you, and how often you should undergo screening.
Identify inflammation of the intestinal wall that occurs in inflammatory bowel diseases, such as ulcerative colitis or granulomatous colitis (Crohn's disease). Also, a barium enema may be done to monitor the progression of these conditions.
Detect structural abnormalities in the large intestine, such as narrowed areas (strictures) or pockets or sacs (diverticula) in the intestinal wall.
Help correct the situation in which the end of the small intestine protrudes into the large intestine (ileocolic intussusception) in a child.
How to Prepare
Before a barium enema, tell your doctor 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.
The preparation for a barium enema usually involves a very thorough cleaning of the large intestine, because the colon must be completely clear of stool (feces) and gas. Even a small amount of fecal material can affect the accuracy of the test.
The preparations usually begin with a clear-liquid diet (no solid, high-residue foods) for 1 to 3 days before the test.
On the day before the test, you should drink very large amounts of noncarbonated clear liquids. You will then take a combination of laxatives (often castor oil, magnesium citrate, or bisacodyl) to empty your intestines.
Also on the day before the test, you may be asked to take a warm tap water enema to clean any remaining feces from your colon.
On the day of the examination, you may need to repeat the tap water enema until the liquid that passes is free of any stool particles. As an alternative, you may be given a rectal suppository or a commercially prepared enema (such as a Fleets enema) the morning of the test.
How It Is Done
The test is done by a doctor who specializes in using X-rays (radiologist) and one or two assistants in a doctor's office, a hospital radiology department, or an outpatient radiology center. It generally does not require an overnight stay in the hospital.
You will need to remove all your clothing and put on a special gown before the test. You may want to bring a robe and socks from home to help keep you warm, although you may have to remove the robe for the test. Also, some of the barium may get on your robe or socks during the test.
If you have anal soreness or irritation after using the laxatives and enemas, you may be able to use a local anesthetic salve to numb the anal area during the test. The salve should be applied 15 to 20 minutes before the examination starts.
You will lie on the X-ray table while a preliminary X-ray film is taken. While you are lying on your side, a well-lubricated enema tube will be inserted gently into your rectum. The barium contrast material, stored in a hanging bag, is then allowed to flow slowly into your colon. A small balloon on the enema tip may be inflated to help you hold in the barium. Tightening your anal sphincter muscle (as if you were trying to hold back a bowel movement) against the tube and taking slow, deep breaths may also help. Occasionally, an injection of medication to relieve the cramping may be given.
Your doctor will observe the flow of the barium through your colon on an X-ray fluoroscope monitor that is similar to a television screen. You will be asked to turn to different positions, and the table may be tilted slightly to help the barium flow through your colon and to take X-rays from different directions (sides, front, and back). The doctor may also press gently on your abdomen with a hand or a plastic paddle to help move the barium through your intestines. If a double-contrast study is being done, the barium will be drained out and then air will be injected into your colon.
At certain times, X-ray pictures called spot films will be taken of different areas of your colon. You will need to hold your breath and lie completely still for a few seconds while these pictures are taken.
The enema tube is then removed, and you will be given a bedpan or be taken to the toilet to expel as much of the barium as you can. One or two additional X-ray pictures (post-evacuation films) will then be taken.
A single-contrast study usually takes 30 to 45 minutes, although the actual time the barium is held inside is only 10 to 15 minutes. A double- or air-contrast study may take up to an hour. After the examination you may resume your regular diet, unless otherwise instructed. Be sure to drink plenty of liquids to replace those you have lost and to help flush the remaining barium out of your system.
How It Feels
The procedure can be uncomfortable and tiring, but usually it does not last very long.
Many people report that the preparation and bowel cleaning are the most difficult parts of the test. The castor oil has an unpleasant taste, and the frequent bowel movements can be tiring. Also, the anal area can become quite sore during the process. Warm sitz baths or a local anesthetic salve (such as Preparation H) can help ease this discomfort.
The test itself may be embarrassing. You may worry that you won't be able to hold the barium and that it will leak onto you or onto the table. The doctor and technologists who perform this procedure are accustomed to such mishaps and will be able to help you.
The X-ray table is hard and sometimes cold because air-conditioning is used to keep the equipment cool. When the barium first flows into your colon, it may feel a bit cool. As your colon fills, you may feel a sensation of fullness, moderate cramping, and a strong urge to have a bowel movement. If an air-contrast study is performed, you may feel increased cramping or gas pains from the distention of the large intestine when the air is introduced. Taking slow, deep breaths through your mouth can help you relax.
You may feel tired for a day or so after the test. You should arrange for someone to drive you home after the test. This test can be especially exhausting for elderly or weakened people.
For 1 to 2 days after the test it is normal to notice some of the residual barium (a whitish or pinkish material) in your bowel movements. Notify your doctor immediately if:
You have rectal bleeding.
You experience severe abdominal pain.
You have a fever higher than 100.5°F (38.1°C).
You do not have a bowel movement within 2 days following the test.
Risks
There is always some concern about the effects of exposure to any radiation, including the low level of radiation used for this test. However, if the test is really necessary, the radiation risk is generally very low compared with the benefits.
Occasionally the barium remaining in the colon hardens, causing severe constipation (impaction) or obstruction. To decrease the risk of impaction, drink extra fluids following the procedure and, if necessary, take an enema or mild laxative after the test.
A more serious, though exceedingly rare, complication is perforation of the bowel. Under the pressure from the barium or air, a weakened section of the colon may break open, allowing the intestinal contents to spill into the abdominal cavity. Rupture of the colon may occur in people whose bowel wall has been weakened by intestinal problems like inflammatory bowel diseases, ulcerative colitis, or Crohn's disease. However, a ruptured colon occurs in fewer than 1 in 20,000 examinations. The break in the intestine wall can be treated with antibiotics and repaired surgically.
Results
During the test, the fluoroscopic monitor provides the radiologist with some results, which are recorded on X-ray films. The radiologist then examines all the X-ray films and interprets the results. Final results may be available immediately after the test or the following day.
Barium enema Normal:
The colon appears normal. A normal-appearing appendix rules out a diagnosis of appendicitis.
Abnormal:
One or more problems in the colon are detected.
Failure of a section of colon to fill with barium (filling defects) may be caused by spasms in the colon wall, polyps, cancer, or retained stool.
The barium enema can detect a growth that may be causing an obstruction or narrowing (stricture) in the bowel.
If any polyps or growths on the inner wall of the colon are found, they may need to be evaluated using colonoscopy, and a biopsy may be done to determine whether they are cancerous.
Sacs in the colon wall (diverticulosis) may be detected. These can sometimes become inflamed or infected (diverticulitis).
Other structural defects and inflammation (colitis) of the lining of the colon may indicate the presence of inflammatory bowel disease (ulcerative colitis or Crohn's disease).
A narrowed segment or a twisted loop of bowel (causing an obstruction) may also be seen on this test.
What Affects the Test
The accuracy of this test depends on the colon being completely clear of stool (feces) and gas. Even a small amount of fecal material can affect the results.
Rarely, muscle spasms in the colon wall may be mistaken for possible colon cancer.
Inability to remain still or cooperate during the test can affect the results. The person being tested must be able to cooperate during the test by holding in the barium, holding his or her breath, and assuming different positions as requested.
What to Think About
A barium enema has fewer risks than colonoscopy or sigmoidoscopy (see the medical tests Colonoscopy and Sigmoidoscopy), but small polyps are more likely to be missed. Also, unlike colonoscopy or sigmoidoscopy, polyps cannot be removed during a barium enema. Further evaluation with a colonoscopy is generally recommended if abnormal results are found during a barium enema. To reduce the chance of needing a barium enema followed by a colonoscopy, many doctors recommend colonoscopy alone.
Factors that increase a person's risk for developing colon cancer include a family history of the disease, a personal history of colon polyps or ulcerative colitis, or both. High-fat and low-fiber diets have also been linked to colorectal cancer. Talk to your doctor about which colorectal screening is best for you. Medical experts disagree about routine screening for colorectal cancer.
If you have a suspected abdominal mass, other tests may be done before or after a barium enema. These include abdominal X-rays, ultrasound studies, and computed tomography (CT) scans.
A barium enema provides a good view of the entire colon. A flexible sigmoidoscopy provides a more direct view of the rectum and sigmoid colon, where more than half of colon polyps are usually found. For this reason, a flexible sigmoidoscopy and barium enema are often done at the same time. (See the medical test Sigmoidoscopy.)
Appendicitis is most commonly evaluated by ultrasound or computed tomography (CT). For more information, see the medical tests Abdominal Ultrasound and CT Scan of the Body.
Because a developing fetus is very sensitive to radiation, this test is not done for pregnant women.
If an upper gastrointestinal series is planned, it should be performed after the barium enema. The barium swallowed during an upper GI series may take several days to pass and, therefore, can interfere with the barium study of the colon.
A barium enema should not be done if a person has severe ulcerative colitis, toxic megacolon, acute diverticulitis, or if a perforation of the intestine is suspected. If a contrast enema is necessary but there is an increased risk of an intestinal perforation, a water-soluble contrast may be used instead of barium, which decreases the possibility of perforation.
Credits
Author Renée Spengler, RN, BSN
Associate Editor Daniel Greer
Primary Medical Reviewer Patrice Burgess, MD
- Family Medicine
Specialist Medical Reviewer Arvydas D. Vanagunas, MD
- Gastroenterology
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