What is the test used for?

A barium enema is used to look at the large bowel or colon. A thin coating of a barium compound lines the inside of the colon, and x-rays are taken. Barium looks white on x-ray, and outlines any irregularity of the bowel wall.

What is the preparation for the test?

The colon has to be as clean as possible before the test. If there is a lot of faeces in the bowel, the barium won't be able to flow to the end of the large bowel. Small pieces of faeces left inside the bowel may look like abnormalities.

You will be given a preparation kit to start 2 days before the test. Follow the instructions with the kit. Unfortunately, watery diarrhoea is the desired effect of the preparation.

Will I have to undress?

You will be asked to remove most of your clothes, including your underpants. You will be asked to change into a cotton gown, opened at the back.

Where will I be for the test?

You will be asked to lie on a fluoroscopy table. This is an unfortunately hard table which can move in many directions as well as tilt.

How is the test done?

A barium powder is mixed with water to make about 300ml of thick liquid which is stored in a clear plastic bag. The bag is connected to a tube which is smaller in cross-section than a finger.

The tip of the tube is lubricated and is inserted by the doctor into the rectum. Only 5–8cm (2 to 3 inches) is inside the rectum. Some tubes have a balloon around the tip which can be inflated and used to hold the tube inside the rectum.

The doctor then slowly lets the barium from the bag run into the colon. Initially, there is little sensation, as the actual volume of liquid introduced is small. Gravity is used to flow the liquid around the colon, and the doctor will ask you to lie on your side, back or front to follow the natural loop of the colon.

Once the liquid is inside the colon, the doctor will allow much of the fluid to flow back out into the bag, as the idea is to coat the lining of the bowel with barium to take the x-rays, not to fill the whole bowel with fluid.

The doctor then gently introduces air into the rectum from the bag. This is to force the walls of the colon apart so that any small irregularities of the bowel wall can be seen by x-ray. At this stage you may feel uncomfortable for the first time, and feel you want to go to the toilet, as the natural response of the bowel when distended is to warn you that it is full and to try and contract. Don't worry. It's an unpleasant feeling, but should not be painful. If you experience pain at any time, tell the doctor.

Several x-rays are then taken. Again the doctor will ask you to roll around on the X-ray table to view all the twists and turns of the bowel. The x-rays are then processed and checked by the doctor, who may need to take some more.

After the test, much of the gas and liquid is allowed to flow back into the bag. The tube is then removed, and you can go to the toilet, which is next to the x-ray room.

How long will it all take?

About 20 minutes.

And after the test?

The barium looks like cement, but fortunately does not set like cement! Drink plenty of clear fluids over the next day. And, most importantly, you can now eat!

Does the test use radiation?

Ionising radiation is used.