Use of air enema radiography to assess depth of ulceration during acute attacks of ulcerative colitis.

BACKGROUND Acute colitis is usually assessed by means of plain abdominal radiographs, the diagnostic utility of which can be enhanced by barium enema. Colonoscopy can also be useful. The latter methods may be laborious and carry risk. We describe a radiographic technique using air as the contrast medium to show mucosal or deeper ulceration. METHODS Of 60 patients undergoing colectomy for acute ulcerative colitis, 35 had air enema radiography and 14 had plain films with sufficient amount of spontaneously occurring gas to allow visualisation of the mucosa, during the 10 days before surgery. The degree of inflammation on air enema films and the extent of histopathological ulceration in colectomy specimens were independently graded and compared with each other. Depth of ulceration was compared with clinical data including a preoperative risk stratification, the APACHE II score. FINDINGS The degree of inflammation on air enema radiography correlated significantly with depth of ulceration at histopathological examination (rs 0.61, p<0.001). Presence of mucosal changes had a close association with deep ulceration extending into the muscularis propria layer or beyond (p<0.001). Air enema radiography had a high sensitivity (0.91) for presence of and specificity (0.75) in the exclusion of deep ulceration, with positive and negative predictive values of 0.88 and 0.80. 42 of 49 patients were correctly classified as regards deep ulcers. The correlation between higher preoperative APACHE II scores and severity of histopathological colitis was weak (rs 0.30, p<0.05). INTERPRETATION Air enema radiography reliably assesses the presence of colonic ulceration in patients with an acute attack of ulcerative colitis. It is a first-line investigation to assess the presence of deeper ulceration in acute colitis.