Timing of Rectal Retroflexion Does Not Reduce Patient-Reported Pain: A Randomized Controlled Trial

Background and Aims:A substantial proportion of patients experience moderate to severe discomfort during colonoscopy, which may reduce willingness to undergo future procedures.According to the "peak and end rule," retrospective pain evaluations are disproportionately influenced by the final moments.Rectal retroflexion ("looping") is a potentially painful maneuver typically performed at the end of colonoscopy.We aimed to investigate whether performing rectal retroflexion at the beginning rather than at the end of colonoscopy reduces patient-reported pain. Methods:A multicenter, single-blinded randomized controlled trial at two hospital-based endoscopy between September 2024 and January 2025.A total of 1,118 patients scheduled for colonoscopy were randomized 1:1 to loop-first (n = 521) or loop-last (n = 529) groups.Retroflexion was performed either immediately upon rectal entry or as the final procedural step.All other aspects of colonoscopy followed routine practice.The primary outcome was pain recalled after colonoscopy, measured on a numerical rating scale (0-10).Secondary outcomes included need for supplemental sedation/analgesia, colonoscopy completion rates, and procedure times. Results:Median pain scores did not differ between groups (loop-first: 3 [IQR 1-6] vs loop-last: 3 [IQR 1-5]; p = 0.10).Supplemental sedation/analgesia was required more frequently in the loop-first group (20.7% vs 14.9%; relative risk [RR] 1.23; 95% CI, 1.03-1.48;P = .01).Completion rates were slightly lower in the loop-first group (91.2% vs 93.6%; RR 0.83; 95% CI, 0.64-1.08;P = .14). Conclusions:Timing of rectal retroflexion did not influence overall pain recall.However, looping at the end appears advantageous, being associated with reduced sedation use and higher completion rates.These findings support performing rectal retroflexion as the final step in colonoscopy.Trial registered at ClinicalTrials.gov(NCT06521658)