Carbon dioxide insufflation reduces the relapse of ulcerative colitis after colonoscopy: A randomized controlled trial

BACKGROUND AND AIM: Colonoscopy is necessary for diagnosing and surveilling patients with ulcerative colitis, though it may cause disease flares. Colonoscopy with carbon dioxide (CO(2)) insufflation decreases abdominal discomfort; however, its effect on exacerbation incidence in ulcerative colitis remains unclear. Therefore, this study aimed to evaluate the colonoscopy effects using CO(2) insufflation in patients with ulcerative colitis. METHODS: Overall, 96 remissive patients with ulcerative colitis (partial Mayo score ≤ 2) who underwent total colonoscopy between March 2015 and December 2019 at Osaka University Hospital were enrolled and blindly randomized to the CO(2) (n = 45) and air (n = 51) insufflation group (UMIN-CTR, number: UMIN000018801). The post-procedural abdominal discomfort and the clinical relapse (partial Mayo score ≥ 3) rate within 8 weeks were evaluated. RESULTS: Baseline backgrounds did not differ between the groups. The mean abdominal fullness and pain scores were significantly lower in the CO(2) group than in the Air group immediately (p = 0.0003, p = 0.0003) and 30 min (p < 0.0001, p < 0.0001) after colonoscopy. While the overall clinical relapse rate remained unchanged between the groups, the clinical relapse rate at 8 weeks after colonoscopy was significantly lower in the CO(2) group than in the Air group in patients not in complete remission (Mayo endoscopic subscore ≥ 1, p = 0.049; or partial Mayo score ≥ 1, p = 0.022). CONCLUSIONS: CO(2) insufflation can reduce abdominal discomfort in remissive patients with ulcerative colitis and decrease clinical relapse at 8 weeks after colonoscopy for those not in complete remission.