Family doctor

What is it and what is it used for?

The barium enema is an examination of the colon, or large bowel, looking for abnormalities such as diverticula, polyps and cancer. It is generally done because of symptoms such as pain, bleeding and altered bowel habit, but it may also be done as a screening test, for example in patients with a strong family history of bowel cancer.

Who can have a barium enema?

Because the test utilizes x-rays, it should not be performed on pregnant patients. Anyone else may safely undergo barium enema. Difficulties may be encountered in patients who have very poor mobility, but the examination can be modified to accommodate such patients.

How much radiation exposure is there?

An average barium enema will result in a dose equivalent of approximately 13mSv. To put this into perspective, the average background radiation dose in New Zealand is 2mSv per year. This is the dose that the average person receives from the environment each year. In some populated parts of the world the background radiation is more than 10 times higher, with no detectable increase in cancer incidence. The dose from a barium enema is considered to be safe.

Before the enema

Your bowel must be clean prior to the examination, as any faeces remaining in the colon makes an accurate interpretation difficult. You will be provided with a prescription and detailed dietary instructions prior to the enema. The bowel preparation generally consists of a special low residue diet for 24 hours, and ingestion of a bowel cleansing liquid the night before the enema. A Dulcolax suppository will also be needed the morning of the enema.

What happens during the examination?

The examination is performed by a radiologist who is a medical doctor with specialist training in x-ray examinations. You will be asked to lie on a table that has an x-ray tube and filming device attached. The radiologist may need to do a rectal examination prior to the enema. A tube is then inserted into the rectum, either by the radiographer or radiologist. A small balloon is inflated at the tip of the tube, to prevent the tube from falling out. The tube is connected to a bag containing a suspension of barium.

Barium has a high density, and is visible on x-ray pictures. Barium is not radioactive. The most common type of barium enema is the double-contrast enema. In this, barium is introduced into the lower part of the bowel, followed by air. You will be asked to roll into different positions to allow the barium and air to get all the way around the colon. The table also tilts to assist in this. A number of x-ray pictures will be taken of each part of the colon. Sometimes an injection is necessary to prevent or overcome bowel spasm. The films are subsequently examined by the radiologist, and a report sent to the referring doctor.

In some cases a single contrast barium enema is preferable to the double contrast type. This utilizes a dilute barium suspension and no air. Less rolling from side to side is required, and this test may be more suitable in patients with poor mobility.

Will it hurt?

Many people are needlessly apprehensive of the enema. Generally there should be only mild discomfort, due to distention of the colon with air. The bowel preparation is generally the most unpleasant part of the whole test, and anyone who completes the preparation should have no problem with the enema. As the test is not painful, painkillers are not given. The barium enema has an excellent safety record, with an extremely low risk of bowel perforation. The risk is much lower than that of colonoscopy, another bowel examination with which the barium enema is frequently compared.

After the enema

A bloated sensation may persist for several hours after the enema. Your diet may return to normal immediately, and you should drink plenty of liquid. You will pass the barium over the next few days.