Procedural characteristics.

Background and aimColonoscopy is necessary for diagnosing and surveilling patients with ulcerative colitis, though it may cause disease flares. Colonoscopy with carbon dioxide (CO2) 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 CO2 insufflation in patients with ulcerative colitis.MethodsOverall, 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 CO2 (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.ResultsBaseline backgrounds did not differ between the groups. The mean abdominal fullness and pain scores were significantly lower in the CO2 group than in the Air group immediately (p = 0.0003, p = 0.0003) and 30 min (p p 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).ConclusionsCO2 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.