Computed tomography diagnosed first time diverticulitis and colorectal cancer.

BACKGROUND Computed tomography (CT) with intravenous contrast is the gold standard for diagnosing diverticulitis. Published results concerning follow-up colonoscopy after an episode of acute diverticulitis to rule out cancer are conflicting. This study aimed to evaluate the risk of underlying colonic malignancy in patients diagnosed with a first time diverticulitis with a state of the art CT investigation with intravenous contrast. METHODS Retrospective analysis of all patients with a first episode of diverticulitis diagnosed with CT at Danderyds Hospital, Stockholm, between January 1, 2015, and November 16, 2016. Data on modified Hinchey classification, age, sex, laboratory parameters, body mass index, and colonoscopy findings were recorded. RESULTS The study identified 518 patients with a CT-verified first time diverticulitis. Four hundred twenty-six (82%) of the 518 patients underwent follow-up colonoscopy and constitute our study cohort. CT showed that 402 patients had uncomplicated diverticulitis (modified Hinchey Ia), and 24 patients had complicated diverticulitis (modified Hinchey ≥Ib). Colonoscopy showed cancers in 2 (0.5%) of the 426 patients initially diagnosed as acute diverticulitis. In addition, 13 (3%) patients had advanced adenomas, and 121 (28%) patients had benign adenomas upon follow-up colonoscopy. Patients with CT-verified complicated diverticulitis (modified Hinchey ≥Ib) had a significantly higher risk for colon cancer compared with patients with an uncomplicated first time diverticulitis. CONCLUSION Our study supports routine follow-up colonoscopy after a first episode of CT-diagnosed complicated diverticulitis. In contrast, we do not find an increased risk for neoplasia in patients with uncomplicated diverticulitis.