Novel Modified Water Balloon for Mini-Probe Endoscopic Ultrasonography in Diagnosis of Esophageal and Gastric Submucosal Lesions: A Dual-Center Retrospective Study.

Objective: Endoscopic ultrasonography (EUS) is commonly used for preoperative diagnosis of upper gastrointestinal submucosal lesions (SMLs), but it remains technically challenging due to rapid water drainage and the risk of aspiration. This study evaluated the efficacy and safety of a novel modified water balloon (WB) for mini-probe EUS compared to the conventional water immersion (WI) method. Methods: In this double-center retrospective study, 136 consecutive patients with SMLs were evaluated using novel WB and conventional WI techniques through mini-probe EUS. Notably, sedation was primarily applied in the WB group due to the fluid-confining design, which may serve as a potential confounding factor. The primary outcome, diagnostic accuracy rate, and the secondary outcomes including image quality, procedure time, and safety profile were compared between the two groups. Results: The overall diagnostic accuracy rate in the novel WB group was significantly higher than that in the conventional WI group (84.4% vs 69.4%, P = 0.04). The novel WB group achieved a higher proportion of high-quality images (P < 0.05) and significantly shorter mean procedure times (P < 0.01). No aspiration events occurred in the novel WB group, despite some cases involving deep sedation. Overall minor complication rates did not differ significantly between two groups (P > 0.05). Conclusion: The novel modified WB technique provides a practical and cost-effective acoustic window for esophageal mini-probe EUS, demonstrating superior procedural efficiency and image quality. Although limited by its retrospective design and variations in sedation protocols, this technique shows potential in mitigating aspiration risks under sedation.