Lower GI Series (barium enema)
A lower GI series, or barium enema, is an x-ray test in which a white liquid, called barium, is placed into the rectum and colon through the anus to enhance x-ray pictures of the large bowel (colon). These x-rays are used to define normal and abnormal anatomy of the colon and rectum. Colon and rectal abnormalities that can be detected include diverticulosis,
diverticulitis, abnormal colon movement, dilation of the colon, polyps, and cancers of the colon and rectum.
A barium enema may be performed for a variety of reasons, including to aid in the diagnosis of colon and rectal cancer (or colorectal cancer), and inflammatory disease. Detection of polyps (a benign growth in the tissue lining of the colon and rectum), diverticula (a pouch pushing out from the colon), and structural changes in the large intestine can also be established with this test. The double-contrast barium enema is the best method for detecting small tumors (such as polyps), early inflammatory disease, and bleeding caused by ulcers.
The decision to perform a barium enema is based on a person's history of altered bowel habits. These can include diarrhea, constipation, any lower abdominal pain they are currently exhibiting, blood, mucus, or pus in their stools. It is also recommended that this exam be used every five to 10 years to screen healthy people for colorectal cancer, the second most deadly type of tumor in the United States. Those who have a close relative with colorectal cancer or have had a precancerous polyp are considered to be at an increased risk for the disease and should be screened more frequently to look for abnormalities.
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 detailed view of the inner surface of the colon, making it easier to see small polyps, colorectal cancer, or inflammation.
What's the preparation for a barium enema?
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. In order to conduct the most accurate barium enema test, the patient must follow a prescribed diet and bowel preparation instructions prior to the test. This preparation commonly includes restricted intake of diary products and a liquid diet for 24 hours prior to the test, in addition to drinking large amounts of water or clear liquids 12-24 hours before the test. Patients may also be given laxatives, and asked to give themselves a cleansing enema.
The preparations usually begin with a clear liquid diet for 1 to 3 days before the test. 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. 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 Fleet enema, the morning of the test.
How is a barium enema preformed?
A barium enema test is done by a 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.
To begin a barium enema, the patient will lie with their back down on a tilting radiographic table in order to have x rays of the abdomen taken. After being assisted to a different position, a well-lubricated rectal tube is inserted through the anus. This tube allows the physician or assistant to slowly administer the barium into the intestine. While this filling process is closely monitored, it is important for the patient to keep the anus tightly contracted against the rectal tube to help maintain its position and prevent the barium from leaking. This step is emphasized to the patient due to the inaccuracy that may be caused if the barium leaks. A rectal balloon may also be inflated to help retain the barium. The table may be tilted or the patient moved to a different position to aid in the filling process.
As the barium fills the intestine, x rays of the abdomen are taken to distinguish significant findings.There are many ways to perform a barium enema. One way is that shortly after filling, the rectal tube is removed and the patient expels as much of the barium as possible. Upon completing this, an additional x ray is taken, and a double-contrast enema may follow. If this is done immediately, a thin film of barium will remain in the intestine, and air is then slowly injected to expand the bowel lumen. Sometimes no x rays will be taken until after the air is injected.
What're the complications of a barium enema?
While a barium enema is considered a safe screening test used on a routine basis, it can cause complications in certain people. There is always some concern about the effects of exposure to any radiation, including the low level of radiation used for a barium enema test. However, if the test is necessary, the radiation risk is generally very low compared with the benefits.
Those who have a rapid heart rate, severe ulcerative colitis, toxic megacolon, or a presumed perforation in the intestine should not undergo a barium enema. The test can be cautiously performed if the patient has a blocked intestine, ulcerative colitis, diverticulitis, or severe bloody diarrhea. Complications that may be caused by the test include perforation of the colon, water intoxication, barium granulomas (inflamed nodules), and allergic reaction. These are all very rare.