What is the difference between a double contrast barium enema and a colonoscopy?

Imaging vs looking: A Barium Enema is performed by a radiologist by flowing contrast solution into the colon and then taking x-rays of the abdomen after the lining of the intestine has been coated. Sigmoidoscopy or colonoscopy is performed by a gastroenterologist who uses a flexible scope and camera to look directly into the colon at the intestinal lining.