The patient is then x-rayed to provide a control starting point. After that, barium sulphate mixed in a liquid, which is opaque to x-rays, is inserted through a tube inserted in the anus. The x-rays are then turned on while the liquid flows into the large intestine, and the results are shown in real time on a flouroscope. As the liquid flows into the large intestine, the shape of the organ is outlined on the flouroscope and can show obstructions, polyps, and diverticulosis. The procedure will also show Intussusception, but in many cases this condition will resolve itself in response to the enema.
Although the barium enema exposes a patient to less radiation than an abdominal CT scan, it does pose a risk of perforation. In addition, if the large intestine is perforated already, the barium sulphate may cause problems when trying to correct the condition as it will often obscure the surgical field. In cases where perforation is suspected, a water-soluble contrast is used instead of barium sulphate.