Radiology in the current assessment of ulcerative colitis.

Plain abdominal radiography in acute ulcerative colitis is essential to detect acute colonic complications, such as acute dilatation and free perforation. Sealed perforations may not be detected. Useful information can be gained as to the extent and severity of the mucosal lesions, but can be unreliable so that a contrast examination is required. The double contrast barium enema is more accurate than the single contrast study in revealing the early mucosal lesions of colitis. It is the examination of choice to show the extent and severity of disease, and is of considerable value in the differential diagnosis of colitis. In active colitis, the unprepared double contrast barium enema is recommended. The success of the examination relies on the absence of fecal residue adjacent to an active mucosa. The technique, uses, and limitations of this type of examination are described. In the long-term management of colitis, the role of radiology is to show the presence of extensive disease, which indicates an increased risk of malignancy. Lesions such as strictures or polyps may be found and are more likely to be benign than malignant, but confirmation often requires endoscopic biopsy. In the search for malignancy regular barium enema examination is not recommended, as this can only reveal an overt tumor, whereas premalignancy can be detected histologically from an endoscopic biopsy.