Follow-up Colonoscopy for Detection of Missed Colorectal Cancer after Diverticulitis

Background and aims Colonoscopy is often recommended following an episode of diverticulitis to exclude missed colorectal cancer (CRC). This is a controversial recommendation based on limited evidence. We estimated the prevalence and odds of CRC and advanced colorectal neoplasia on colonoscopy in patients with diverticulitis compared to CRC screening. Methods Using data from the Gastrointestinal Quality Improvement Consortium registry, we performed a cross-sectional study with patients ≥40 years old undergoing outpatient colonoscopy for an indication of diverticulitis follow-up or CRC screening. The primary outcome was CRC. The secondary outcome was advanced colorectal neoplasia. Odds ratios and 95% confidence intervals were calculated. Results We identified 4,591,921 outpatient colonoscopies performed for screening and 91,993 colonoscopies for diverticulitis follow-up. CRC prevalence was 0.33% in colonoscopies for screening and 0.31% in colonoscopies for diverticulitis. Compared to screening, patients with diverticulitis were less likely to have CRC (adjusted OR 0.84, 95% CI 0.74-0.94). CRC prevalence decreased to 0.17% in colonoscopies performed for diverticulitis only. Compared to screening, patients with diverticulitis as the only indication were less likely to have CRC (adjusted OR 0.49, 95% CI 0.36-0.68). CRC prevalence increased to 1.43% in patients with complicated diverticulitis. Compared to screening, patients with complicated diverticulitis were more likely to have CRC (adjusted OR 3.57, 95% CI 1.59-8.01). Conclusion The risk of CRC cancer is low in most patients with diverticulitis. Patients with complicated diverticulitis are the exception. Our results suggest that colonoscopy to detect missed CRC should include diverticulitis patients with a complication and those not current with CRC screening.