Colitis. Coloured barium X-ray showing a narrowed section (stricture, red) of a descending colon (purple/white, part of the large intestine). Such narrowing can result from inflammation of the lining of the colon, for example in ulcerative colitis. In this condition the colon lining becomes inflamed and ulcered, causing abdominal pain and bloody diarrhoea. Its cause is unknown, but the symptoms can be treated with anti- inflammatory drugs. In severe cases a colectomy (removal of the colon) may be required.