Background: The use of computed tomography (CT) in acute left colonic diverticulitis remains controversial. The purpose of this study was to define the value of CT both during the acute phase of inflammation and, later, to indicate secondary complications after successful medical treatment.
Methods: Some 423 patients with radiologically or histologically proven diverticulitis were studied prospectively from 1986 to 1995. Diverticulitis was considered moderate when CT showed localized thickening of the colonic wall (5 mm or more) and inflammation of pericolic fat; it was considered severe when abscess and/or extraluminal air and/or extraluminal contrast were observed.
Results: The sensitivity of CT was 97 per cent. Of 42 patients who failed conservative treatment, 32 had severe diverticulitis on CT, compared with 74 (24 per cent) of 303 who had successful conservative treatment (P < 0.0001). After a median follow-up of 46 months, 60 (20 per cent) of 300 patients had secondary complications despite initially successful conservative treatment: 28 (47 per cent) of these had initial severe diverticulitis on CT compared with 44 (19 per cent) of 236 patients who had no complications (P < 0.0001).
Conclusion: Abscess formation and extracolonic contrast or gas are findings that may be used to predict failure of medical treatment during the first admission and a high risk of secondary complications after initially successful medical management of acute diverticulitis.