Background/Aims: The necessity for pharyngeal anesthesia during upper gastrointestinal endoscopy is controversial. This study aimed to compare the observation ability with and without pharyngeal anesthesia under midazolam sedation. Methods: This prospective, single-blinded, randomized study included 500 patients who underwent transoral upper gastrointestinal endoscopy under intravenous midazolam sedation. Patients were randomly allocated to pharyngeal anesthesia: PA+ or PA-groups (250 patients/group). The endoscopists obtained 10 images of the oropharynx and hypopharynx. The primary outcome was the non-inferiority of the PA-group in terms of the pharyngeal observation success rate. Results: The pharyngeal observation success rates in the pharyngeal anesthesia with and without (PA+ and PA-) groups were 84.0% and 72.0%, respectively. The PA-group was inferior (p=0.707, non-inferiority) to the PA+ group in terms of observable parts (8.33 vs. 8.86, p=0.006), time (67.2 vs. 58.2 seconds, p=0.001), and pain (1.21±2.37 vs. 0.68±1.78, p=0.004, 0-10 point visual analog scale). Suitable quality images of the posterior wall of the oropharynx, vocal fold, and pyriform sinus were inferior in the PA-group. Subgroup analysis showed a higher sedation level (Ramsay score ≥5) with almost no differences in the pharyngeal observation success rate between the groups. Conclusions: Non-pharyngeal anesthesia showed no non-inferiority in pharyngeal observation ability. Pharyngeal anesthesia may improve pharyngeal observation ability in the hypopharynx and reduce pain. However, deeper anesthesia may reduce this difference.

BACKGROUND Pharyngeal anesthesia’s role in improving observational ability during upper gastrointestinal endoscopy is controversial. No randomized controlled trials have evaluated observational ability with and without pharyngeal anesthesia (PA + vs. PA- group) under sedation with midazolam. We report the non-inferiority of the PA- group in the pharyngeal observation success rate. METHODS This prospective, single-blinded, randomized study included 500 patients, randomly allocated to PA + or PA- groups (250 cases/group), undergoing transoral upper gastrointestinal endoscopy under intravenous sedation with midazolam. RESULTS The pharyngeal observation success rate was 72.0% and 84.0% in the PA- and PA + groups, respectively; non-inferiority in PA- group was not observed (p = 0.707). In the PA- group, observable sites were fewer (8.33 vs 8.86, p = 0.006), time was longer (67.2 vs. 58.2 s, p = 0.001), and pain scores were higher. Image quality at the posterior wall of oropharynx, vocal fold and pyriform sinus was significantly inferior in PA- group. Subgroup analysis showed a higher sedation level (Ramsay score ≥ 5); no differences in the pharyngeal observation success rate were observed between the groups. CONCLUSION Pharyngeal anesthesia may improve pharyngeal observation ability in the hypopharynx and reduce pain. However, this difference may be reduced with deeper sedation.