Current colonoscopy quality indicators recommend a minimum withdrawal time (WT) of 6 minutes. However, prolonged WT can reduce throughput and may not account for endoscopist experience or bowel preparation quality. Whether a 6-minute WT remains necessary when examinations are performed by experienced endoscopists with excellent preparation is uncertain. We conducted a study among experienced endoscopists and patients with high-quality preparation (Boston Bowel Preparation Scale [BBPS] ≥ 8) to compare a 5-minute WT with a 6-minute WT for adenoma detection rate (ADR) and adenoma miss rate (AMR).

In this multicenter, randomized controlled trial, 423 patients were enrolled from June 2023 to March 2025 across five centers (Wuxi People’s Hospital; Jiangsu Province People’s Hospital; Xuzhou First People’s Hospital; the Second Affiliated Hospital of Soochow University; Taizhou People’s Hospital). Each colonoscopy involved two withdrawals performed by the same endoscopist. Participants were randomized to a 5-minute WT group (first withdrawal 5 minutes, second withdrawal 6 minutes; n = 214) or a 6-minute WT group (first withdrawal 6 minutes, second withdrawal 6 minutes; n = 209). A timer standardized withdrawal speed. Primary outcomes were ADR and AMR.

Baseline demographic and clinical characteristics were similar between groups (Table 1). Procedural metrics—including bowel preparation quality, cecal intubation rate, cecal intubation time, cecal intubation distance, use of abdominal compression, and patient repositioning—were comparable (Table 2). Overall ADR did not differ between the 5-minute and 6-minute groups (39.7% vs 43.5%; P = 0.606). ADR during the first withdrawal (36.0% vs 36.8%; P = 0.934) and the second withdrawal (10.7% vs 13.4%; P = 0.492) was likewise similar. AADR showed no significant differences overall (4.7% vs 5.3%; P = 0.954), during the first withdrawal (4.7% vs 5.3%; P = 0.956), or during the second withdrawal (0.5% vs 0.5%; P = 0.999). Similarly, polyp detection rate (PDR) and sessile serrated lesion detection rate (SSLDR) did not differ between groups. The patient-level AMR was numerically lower in the 5-minute group than in the 6-minute group (27.1% vs 30.8%; P = 0.567), indicating fewer missed adenomas with the 5-minute WT, although this difference was not statistically significant. A similar trend was observed for lesion-level AMR, which was also lower in the 5-minute group than in the 6-minute group (20.2% vs 23.7%; P = 0.188). There were no significant differences in advanced adenoma miss rate (AAMR), polyp miss rate (PMR), or sessile serrated lesion miss rate (SSLMR) (all P>0.05) (Table 3).

Table 3. Detection and miss rate in the two groups

Among experienced endoscopists performing colonoscopy with excellent bowel preparation (BBPS ≥ 8), shortening WT from 6 to 5 minutes did not reduce ADR and was associated with a comparable AMR. A 5-minute WT appears acceptable under these conditions.