Barium Enema Health Article

Definition

A barium enema, also known as a lower GI (gastrointestinal) exam, is a diagnostic test using x-ray examination to view the large intestine (colon and rectum). There are two types of this test: the single-contrast technique, in which barium sulfate solution is injected into the rectum to gain a profile view of the large intestine; and the double-contrast (or air contrast) technique, in which air and barium sulfate are injected into the rectum.

Purpose

A barium enema may be performed to assist in diagnosing or detecting:

• colon or rectal cancer (colorectal cancer)
• inflammatory diseases such as ulcerative colitis
• polyps (small benign growths in the tissue lining of the colon and rectum)
• diverticula (pouches pushing out from the colon)
• structural changes in the large intestine

The double-contrast barium enema is more accurate than the single-contrast technique for detecting small polyps or tumors, early inflammatory disease, and bleeding caused by ulcers because it gives a better view of the intestinal walls.

The decision to perform a barium enema is based on the patient's history of altered bowel habits. These alterations may include diarrhea, constipation, lower abdominal pain, blood, mucus or pus in the stool. It is also recommended that this exam be used every five to 10 years beginning at age 50 to screen healthy people for colon cancer, the second most deadly type of cancer in the United States. Those who have a close relative with colon cancer or who have had a precancerous polyp are considered to be at an increased risk for the disease and should be screened more frequently to detect abnormalities.

Precautions

Although the barium enema is an effective screening method and may lead to a timely diagnosis of a variety gastrointestinal diseases, the test may not detect all abnormalities present in the colon and rectum. In addition, the barium enema visualizes only the large intestine; the small intestine may also require examination with an upper GI series to rule out abnormalities in that area of the digestive tract. Another drawback is that intestinal gas may hinder the accuracy of test results.

As of 2001, numerous studies have shown that a colonoscopy performed by an experienced gastroenterologist is a more accurate initial diagnostic tool for detecting early signs of colorectal cancer than a barium enema. Colonoscopy allows a physician to examine the entire colon and rectum for polyps. In addition, if abnormalities such as polyps are observed during the procedure, these often-precancerous growths may be removed during the procedure and later examined (biopsy). One additional difference between a barium enema and a colonoscopy is that a colonoscopy almost always involves conscious sedation, while the barium enema is an unsedated procedure. Some physicians use flexible sigmoidoscopy (proctosigmoidoscopy) plus a barium enema instead of colonoscopy. However, sigmoidoscopy only visualizes the rectum and the portion of the colon immediately above it (sigmoid colon) and does not allow the physician to remove polyps but only to obtain tissue or stool samples.

Description

To begin a barium enema, the patient lies flat on his or her back 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 sulfate 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 important because the test may be inaccurate 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 different positions 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 expulsion, an additional x ray is taken, and a double-contrast enema exam may follow. If this procedure is done immediately, a thin film of barium will remain in the intestine, and air is then slowly injected to expand the bowel lumen (space in the intestine). Sometimes no x rays will be taken until after the air is injected. The entire test takes about 20-30 minutes.