Acute left colonic diverticulitis--compared performance of computed tomography and water-soluble contrast enema: prospective evaluation of 420 patients.

PURPOSE: The most valuable radiologic examination to be done initially when acute left colonic diverticulitis is suspected is still a matter of controversy. This study compares the performance between water-soluble contrast enema and computed tomography.

METHODS

From 1986 to 1997, all patients admitted in our emergency center with clinically suspected left-colonic diverticulitis had a contrast enema and a computed tomography within 72 hours of their admission, unless clinical findings required immediate laparotomy. They were prospectively included in the study if one or both radiologic examinations showed signs of acute diverticulitis or diverticulitis was surgically removed and histologically proven or both. Diverticulitis was considered moderate when computed tomography showed localized thickening of the colonic wall (5 mm or more) and inflammation of pericolic fat and contrast enema showed segmental lumen narrowing and tethered mucosa; it was considered severe when abscess or extraluminal air or contrast or all three were observed on computed tomography and when one or both of the last two signs were seen on contrast enema. Of 542 patients, 420 who had both computed tomography and contrast enema entered the study.

RESULTS

The performance of computed tomography was significantly superior to contrast enema in terms of sensitivity (98 vs. 92 percent; P = 0.01), which was calculated from patients who had their colon removed and whose diverticulitis was histologically proven, and in the evaluation of the severity of the inflammation (26 vs. 9 percent; P = 0.02). Moreover, of 69 patients who had an associated abscess seen on computed tomography, only 20 (29 percent) had indirect signs of this complication on contrast enema.

CONCLUSIONS

In the diagnostic evaluation of acute left-colonic diverticulitis, computed tomography should be preferred to contrast enema as the initial radiologic examination because of its statistically significant superiority in sensitivity and for its significantly better performance in the detection of severe infection, especially when an abscess is associated with the disease.