Acute left colonic diverticulitis: can CT findings be used to predict recurrence?

OBJECTIVE: We explored CT and demographic predictors for unfavorable outcome of nonoperative treatment in patients with a first event of left colonic diverticulitis.

MATERIALS AND METHODS: We retrospectively analyzed the medical files and CT scans of 312 consecutive patients who were diagnosed as having diverticulitis on an admission CT report or who had a final diagnosis of left colonic diverticulitis. Patients who did not undergo nonoperative treatment or were lost to follow-up (n = 144) were excluded from the study. Admission CT scans of 168 consecutive patients with a diagnosis of left colonic diverticulitis who underwent nonoperative treatment and had an 18-month follow-up were reassessed by three radiologists unaware of the clinical findings. Nonoperative treatment was defined as an attempt to treat the patient with only antibiotics without scheduling them for elective (delayed) surgery. Unfavorable outcome was defined as a failure of nonoperative treatment 18 months after admission that required either surgery or rehospitalization for antibiotic treatment. The risk of unfavorable outcome was modeled using logistic regression as a function of sex, age, and CT criteria including the maximum number of diverticula per 10 cm of colon; the presence of intraabdominal abscess or extraintestinal gas bubbles (< 5 mm diameter) or gas pockets (>or=5 mm); the length and location of the abnormal colonic segment; the maximum thickness of the colonic wall; the presence of associated free intraperitoneal fluid; and the extent of fatty infiltration.

RESULTS: Among these 168 patients, 115 (68%) had an uneventful outcome, but nonoperative treatment failed in 53 (32%). The presence of an abscess (n = 19) or extraintestinal gas pocket (n = 14) were the only CT findings significantly associated with failure of nonoperative treatment. Adjusted odds ratios (95% confidence interval) for failure were 6.18 (1.76-21.68) when an abscess was diagnosed and 4.26 (1.04-17.57) when pockets of free air were observed. Sex and age were not significantly associated with unfavorable outcome of nonoperative treatment.

CONCLUSION: Abscess and pockets of extraintestinal gas 5 mm in diameter or larger correlated with unfavorable outcome of nonoperative treatment. None of the other criteria evaluated were predictive of failure of nonoperative treatment, including bubbles of extraintestinal gas smaller than 5 mm in diameter.