A diagnosis of acute diverticulitis is based on computed tomography (CT). Colonoscopy is commonly performed after the acute event to exclude other diagnoses. This study aimed to determine whether colonoscopy is necessary and what additional information is gained from a colonoscopy after acute diverticulitis.

Acute diverticulitis was diagnosed by clinical criteria and characteristic CT findings. We analyzed the number of patients in whom colorectal cancers were diagnosed and other incidental findings of polyps and other diseases.

A total of 177 patients were analyzed retrospectively. The mean age was 43.3±15.3 years (range, 13-82 years) and 97 patients (54.8%) were male. Sixty-one patients had undergone a colonoscopy within 1 year of the acute attack. Advanced adenomatous lesions and colonic malignancy were not detected. Nineteen patients (31.1%) had ≥1 polyp and 11 patients (18.0%) had an adenomatous polyp. No new or different diagnosis was made after colonoscopy. None of the 116 patients who did not undergo colonoscopy within a year after acute diverticulitis had a diagnosis of colorectal cancer registered with the Korea Central Cancer Registry.

Routine colonoscopy yields little benefit in patients with acute diverticulitis diagnosed by typical clinical symptoms and CT. The current practice of a colonoscopy after acute diverticulitis needs to be reevaluated.