Prevalence of colorectal cancer and advanced adenoma in patients with acute diverticulitis: implications for follow-up colonoscopy

Background and Aims: Guidelines recommend colonoscopy after an episode of diverticulitis to exclude neoplasia but the effectiveness of testing is uncertain. Patients with complicated diverticulitis may be at higher risk for neoplasia, but most patients have uncomplicated disease. We examined the incidence of colorectal cancer (CRC) and advanced adenoma (AA) in patients with diverticulitis compared with patients undergoing screening colonoscopy. Methods: CT scans from January 1, 2008, to May 1, 2013, at the University of Pittsburgh Medical Center (UPMC) were reviewed to identify those with confirmed acute diverticulitis. Subsequent surgical, colonoscopy, and pathology reports were abstracted to identify those with a diagnosis of AA and CRC. The incidence of neoplasia was compared with that reported for screening colonoscopy from a meta-analysis (n = 68,324), and from colonoscopy examinations at UPMC between 2013 and 2015 (n = 28,573). Results: A total of 5167 abdominal/pelvic CT scan reports identified 978 patients with acute diverticulitis, among which 474 (48.5%) patients had undergone at least 1 colonoscopy or gastrointestinal surgery to April 2015. The CRC rate in patients with diverticulitis (13/474, 2.7%) was significantly higher (P < .0001) compared with both the meta-analysis (0.8%) and UPMC (0.3%). The AA rate (19/474, 4.0%) was similar to the rate in the meta-analysis (5.0%, P = .39) but significantly lower than at UPMC (7.7%, P = .003). The incidence of AA or CRC in complicated diverticulitis (10/141, 7.1%) did not differ significantly (P = .85) from the incidence of AA or CRC in uncomplicated diverticulitis (22/332, 6.6%). Conclusions: CRC after diverticulitis was significantly higher than that observed at screening colonoscopy and was not limited to complicated disease. Colonoscopy is advisable after the diagnosis of diverticulitis.