Association of lidocaine mucilage administration timing with gastric mucosal visibility and pharyngeal anesthesia during transoral gastrointestinal endoscopy

Lidocaine mucilage is a compound preparation commonly used before gastroscopy to provide topical pharyngeal anesthesia and improve gastric mucosal visibility. However, the optimal interval between administration and endoscopic insertion remains unclear, particularly because excessive shortening of this interval may compromise mucosal visualization, whereas prolonged waiting may affect workflow and patient experience. In this single-center prospective observational study, 317 adult patients undergoing routine upper gastrointestinal endoscopy were evaluated according to the time interval between administration of 7 mL lidocaine mucilage and the start of examination. Gastric mucosal visibility and pharyngeal anesthesia were assessed using predefined scoring systems. The results showed that when the interval exceeded 5 min, gastric mucosal visibility was significantly improved compared with shorter intervals, while no clear additional gain in visibility was observed with further prolongation. Overall pharyngeal anesthesia was adequate, and the incidence of adverse events was low, with only mild events such as cough and retching and no cases of hypoxemia or allergic reaction.