[Ultrasonography in acute diverticulitis of the colon: semiologic features]

To assess the ultrasonographic (US) patterns of acute colonic diverticulitis, we prospectively examined 21 patients. US was performed in all of them, CT in 13/21, contrast enema in 18/21 and endoscopy in 2/21 patients. US follow-up was carried out in 15/17 patients managed with conservative treatment. To analyze the US patterns of simple diverticula, we carried out an in vitro study of two surgical specimens with simple colonic diverticulosis. Wall thickening was seen in 21/21 cases, diverticula in 19/21, changes in pericolic fat in 11/21, local tenderness on gradual compression in 19/21 and changes in peristaltic activity in 21/21 cases. Even though diverticula may appear differently, we found 4 main patterns: round or linear hyperechoic pericolic outpouchings with no definite wall, usually with shadowing or reverberation artifacts (pattern 1), a saccular focus with a well-defined wall and various contents (pattern 2), a tubular structure with no content but with central linear echoes (pattern 3), and a flask-like or arrowhead-like hypoechoic focus (pattern 4). Patterns 1, 2 and 3 were shown in inflamed colic segments and in unaffected adjacent tracts, both in the acute phase and at follow-up, with no relevant morphological changes. In contrast, pattern 4 was observed in 10/19 patients, always in the acute phase and in affected colic tracts. The follow-up showed a decrease in size in 3 cases and a change to patterns 1, 2 or 3 in 7 patients. The authors believe pattern 4 to represent inflamed diverticula, while patterns 1, 2 and 3 indicate simple diverticula. Moreover the detection of diverticula and thickened wall segments does not necessarily indicate diverticulitis: thus, the diagnosis of this condition must rely on the presence of several signs, the most specific of which were, in our series, the flask-like and arrowhead-like patterns, presumptively expressing peridiverticular abscess.