Bowel preparation for same-day bidirectional endoscopy improves gastric mucosal visualization: a retrospective cohort study

To compare gastric mucosal cleanliness between patients undergoing gastroscopy alone and those undergoing same-day bidirectional endoscopy, and to evaluate the potential effect of bowel preparation on gastric mucosal visualization. This single-center retrospective cohort study included 1,762 patients who underwent endoscopy at Linyi Central Hospital between January and March 2025. Patients were classified into a gastroscopy-only group ( n = 866) and a same-day bidirectional endoscopy group ( n = 896). Both groups received routine pre-endoscopic medication, including simethicone, streptokinase protease plus sodium bicarbonate solution, and lidocaine hydrochloride mucilage. Patients in the bidirectional endoscopy group additionally received polyethylene glycol-based bowel preparation. Gastric mucosal cleanliness scores, number of flushes, gastroscopy duration, minor lesion detection, number of lesion types per patient, and endoscopist satisfaction were compared between groups. Baseline characteristics were comparable between the two groups. Compared with the gastroscopy-only group, the same-day bidirectional endoscopy group had significantly better gastric mucosal cleanliness scores, fewer flushes (2.11 ± 1.66 vs. 2.73 ± 2.18), shorter gastroscopy duration (8.71 ± 0.94 vs. 9.53 ± 1.75 min), a higher minor lesion detection rate (54.35% vs. 46.77%), more lesion types detected per patient (0.59 ± 0.57 vs. 0.51 ± 0.58), and higher endoscopist satisfaction (94.20% vs. 86.84%) (all P < 0.05). Same-day bidirectional endoscopy with polyethylene glycol-based bowel preparation was associated with improved gastric mucosal cleanliness, reduced need for flushing, shorter gastroscopy duration, higher minor lesion detection rate, and greater endoscopist satisfaction. These findings suggest that bowel preparation may help optimize mucosal visualization during upper gastrointestinal endoscopy.