A randomized prospective study comparing single-balloon-assisted colonoscopy and cap-assisted colonoscopy in patients with previous incomplete conventional colonoscopy.

INTRODUCTION: Cecal intubation may be unsuccessful by conventional colonoscopy in some patients. Single-balloon-assisted colonoscopy (SBC) and cap-assisted colonoscopy (CAC) were studied to solve this problem. There was no head-to-head comparison between them. METHODS: We conducted a randomized study from 2018 to 2021 to compare cecal intubation rate of SBC and CAC in patients with previous incomplete conventional colonoscopy. We recruited patients with incomplete conventional colonoscopy in two hospitals in Hong Kong. Patients were randomized into SBC group and CAC group in 1:1 ratio. In the case of failure in cecal intubation by allocated method, alternative modality would be performed as rescue. RESULTS: Forty-four patients were recruited. Cecal intubation rate was superior in SBC group (22/22, 100%) than CAC group (16/22, 72.7%) (P = 0.02). No difference in cecal intubation time, polyp detection rate, and diagnostic gain in area not examined previously. SBC induced less discomfort (modified Gloucester comfort score 2.14 vs 2.63, P = 0.03) with use of comparable amount of midazolam and fentanyl as CAC. For patients failed cecal intubation by CAC, all (n = 6) were rescued successfully by SBC. Body weight, body mass index (BMI), and waist circumference were greater in rescue subgroup. More patients were obese (BMI ≥ 25 kg/m) in rescue subgroup (67% vs 19%). None in rescue subgroup had history of successful cecal intubation by conventional colonoscopy (0% vs 56%, P = 0.046). However, we failed to demonstrate significant association in multivariate analysis owing to small sample size. No adverse event was noted. CONCLUSION: SBC is superior to CAC in cecal intubation in patients with previous incomplete conventional colonoscopy.