Cancer detected in fewer than 1% of patients undergoing colonoscopy after uncomplicated diverticulitis

Reference

Rottier SJ, van Dijk ST, van Geloven AAW, et al. Meta-analysis of the role of colonoscopy after an episode of left-sided acute diverticulitis. Br J Surg 2019;106(8):988-997.

Synopsis

These authors searched PubMed and EMBASE to identify studies that evaluated neoplasm detection by colonoscopy in patients within one year of CT-confirmed acute left-sided diverticulitis. They did not describe searching for unpublished studies, and explicitly excluded reviews, conference abstracts, letters to the editor, animal studies, and studies with fewer than 10 patients. Two authors independently evaluated studies for inclusion and evaluated the included studies for risk of bias. They settled discrepancies by discussion. They describe using a random-effects model to estimate the prevalence rates of advanced colonic neoplasm and colorectal carcinoma. This will generate slightly more conservative estimates and wider confidence intervals, and is probably appropriate in light of the variability one might expect to find among the various studies. Ultimately, the authors included 17 studies with 3296 patients, 959 of whom had uncomplicated cases of diverticulitis. Four studies were prospective cohorts and 13 were retrospective. Four studies only included patients with left-sided diverticulitis; the remainder did not report the proportion of patients with left-sided disease. The authors point out that these studies took place in the Western world where they claim "the vast majority" of cases are left-sided. Eight of the studies excluded patients who had colonoscopy before the onset of acute diverticulitis (6 months to 2 years). The authors rated the quality of the studies as moderate to good. Only 2 studies had a comparison group of asymptomatic patients, and reported no statistically significant increased risk of colorectal carcinoma among the afflicted patients. Overall, the pooled rate of colorectal carcinoma was 2.1% (95% CI 1.5 - 3.1). Among patients with uncomplicated events, the pooled rate was 0.5% (0.2 - 1.2) and among those with complicated cases (accompanied by abscess, perforation, or fistula) the pooled rate was 8.3% (4.2 - 15.8). Finally, the rate of advanced colorectal neoplasia was 6.9% (5.9 - 9.4). Among the studies that reported the location of the neoplasms, 41 of 43 were at the site of presumed diverticulitis. We commonly find that harms are not reported, and in this case only 4 studies reported them: 3 perforations among 683 procedures.