[The imaging diagnosis of colovesical fistulae secondary to diverticulitis]

The diagnostic procedures proposed in the evaluation of sigmoidovesical fistulas complicating diverticulitis are various and their effectiveness is still not well established.

Personal experience is based on 14 cases of colovesical fistulas secondary to sigmoid diverticulitis. Several diagnostic tools were employed: plain abdominal film (10 cases), large bowel enema (12), urography (3), cystography (2), sonography (4), and CT (5). The semeiotics of these fistulas were distinguished in direct, indirect, secondary, and related to the underlying disease.

The fistulous tract itself was recognized in 100% of the cases with sonography, in 75% with enema, in 60% with CT, in 33% with urography, and in none with cystography. Vesical gas was visible in 100% of the cases with sonography and CT, and in 40% with plain radiographs. Diffusion of contrast medium was present in 91% of the cases with enema, in 60% with CT, and in 33% with urography. Focal thickening and/or irregularity of the bladder wall was evident with cystography and urography in 67% of the cases, with CT in 60%, with sonography in 50%, with enema in 8%. Diverticulosis/diverticulitis was recognizable in 100% of the cases with CT, in 91% with enema, in 25% with sonography. A paravesical abscess was recognizable in 40% of the cases with CT, in 25% with sonography, in 8% with enema.

The radiourological procedures, though of limited use in our series, have a poor effectiveness. Large bowel enema and, specially, CT confirm as the method with greatest accuracy in the evaluation of these fistulas. The sonographic examination, according to personal preliminary experiences, is a valuable diagnostic alternative. Sonography and CT allow analysis of the perivisceral structures and, if compared with barium enema, provide a larger number of information on diverticulitis, which is essentially an extraluminal disease, and its complications.