Colitis. Colitis. (A) Plain radiograph showing dilated loop of transverse colon (white arrow), consistent with toxic megacolon, and featureless oedematous descending colon secondary to inflammatory bowel disease. (B) Plain radiograph of a different patient showing a long segment of thick walled and oedematous descending colon (white arrows). (C) This was confirmed on the CT scan (white arrow). Rachel E Musson et al. Postgrad Med J 2011;87:274-287 Copyright © The Fellowship of Postgraduate Medicine. All rights reserved.