Medical Q&As

Colonoscopy - versus barium enema?

Why, following a colonoscopy, would a barium enema be necessary? Surely the colonoscopy would be definitive?

Colonoscopy is superior to barium enema in the detection of small lesions and also affords the opportunity of taking biopsies, which is technically impossible in a barium study. However, sometimes it may not be possible to visualize the first section of the colon, which is also known as the ascending colon. During the process of colonoscopy the colonoscope is introduced through the anus and is then guided up through the rectum and then into the descending colon. It is then guided through a ninety-degree turn into the transverse colon and again turns a further sharp corner as it is guided down into the ascending colon. Given the slightly tortuous nature of the route it sometimes happens that the doctor is unable to guide the scope into the ascending colon and therefore is unable to fully visualize the full extent of the colon. It can also happen that the colon might not have been fully evacuated despite apparently adequate preparation and the remaining faecal material in the colon can obscure the view. In these various scenarios the barium study allows the doctor to examine that portion of the colon that was inaccessible with the scope.