By Dr Ananya Mandal, MD
A barium enema, in principle, is similar to a barium meal or barium follow-through but is used specifically to obtain X-ray images of the large intestine. Unlike the barium meal and follow through procedures where a patient swallows the barium solution, the barium enema involves insertion of a small tube via the anus into the colon where the liquid is then infused.
When is this test performed?
A barium enema is performed in cases of suspected bowel polyps or diverticulitis. Patients with abdominal pain or bleeding on defecation may be advised to have this test.
The lower intestine needs to be completely empty before the barium enema is performed, so the patient is usually given a laxative the night before the procedure is due. A patient may also be advised to restrict their diet to soft or liquid food intake for two days prior to the test. The patient is instructed not to eat or drink anything after midnight before the enema, as residual food matter shows up on X-ray and interferes with image interpretation.
At the hospital, a patient is asked to remove dentures, jewellery, clothes and all metallic objects from their person and to wear a hospital gown. Metals may compromise image accuracy.
Once in the X-ray room, the patient is laid on a tilting table, over which an X-ray tube is suspended and connected to a monitor where images are displayed. The first image taken is checked to ensure the lower abdomen is clear. Next, the enema tube is inserted into the rectum via the anus. The tube is lubricated with a local anesthetic to numb any pain.
Liquid barium flows through the enema tip a little at a time, coating the wall of the lower intestine and allowing radiographic visualization of the gastrointestinal tract. After the barium is infused, the patient is asked to turn over to one side as this helps the physician study the colon and obtain a series of X-rays.
The patient may feel a pressure or fullness in the bowel and have an urge to defecate, but they are asked to try and hold in the enema until the procedure is complete. Afterwards, the toilet may be used to expel the enema and another image is then taken to check there is no residual barium in the large intestine.
In some patients, air may be introduced along with the barium solution. This procedure is commonly called a double-contrast or air-contrast barium enema. The underlying principle is that air expands the walls of the colon, allowing the radiographer to view the barium-coated lining in more detail.
Exposure to X-rays carries a similar risk as exposure to ionizing radiation. However, the amount of radiation a person is exposed to during an X-ray is very low and risks are minimal. No risks are associated with the use of barium liquid because it is not absorbed by the body.
X-rays are harmful to unborn babies and should be avoided by women who are or may be pregnant. The test is performed on females within ten days of the first day of their last menstruation, when the risk of pregnancy is low.
After the test
Some patients may feel abdominal bloating or cramping after a barium enema and the procedure may also lead to constipation. Patients are therefore advised to drink plenty of fluids and eat plenty of fruit and vegetables. Mild laxatives may also help. Stools may be pale or whitish for a few days after the test.
Reviewed by Sally Robertson, BSc