Underwater endoscopic stenting: A salvage technique for complex malignant duodenal obstruction

Endoscopic placement of self-expandable metal stents (SEMSs) is a well-established, minimally invasive treatment for malignant bowel obstruction, providing rapid symptom relief and avoiding emergency surgery. The European Society of Gastrointestinal Endoscopy guidelines recommend stenting as a palliative alternative for obstructions caused by extracolonic malignancies.[ 1​ ] However, the accurate identification of the stenotic lumen and advancement of the catheter and guidewire remain major technical challenges, particularly in cases of complex extrinsic compression. Although the underwater technique has been described in various endoscopic procedures, its application in stent placement has not been previously reported.[ 2​ ] Herein, we successfully performed underwater endoscopic stent placement in a 44-year-old women with gastric cancer and peritoneal metastases who presented with refractory vomiting and significant weight loss. Images revealed complete obstruction at the horizontal segment of the duodenum due to extrinsic compression from peritoneal metastases ( Figs [ 1 ] – [ 2 ]). Conventional fluoroscopy-guided peroral stenting failed after several hours due to the inability to identify the stenotic orifice ([ Fig. 3 ]). Fig. 1 Computed tomography demonstrating multiple peritoneal metastases with the involvement of the horizontal segment of the duodenum. Fig. 2 Upper gastrointestinal series showing the complete obstruction of the horizontal duodenum. Fig. 3 Fluoroscopy-guided peroral stenting by interventional radiology was attempted but failed after several hours. Due to the patient’s frail condition and high surgical risk, an endoscopic approach was selected after multidisciplinary discussion. Initial attempts were challenging due to duodenal peristalsis and unstable scope positioning ([ Fig. 4 ] ) . Using the underwater technique, continuous water instillation suppressed peristalsis, improved visualization of the stenotic segment and facilitated luminal navigation ([ Fig. 5 ]). This enabled the successful guidewire and catheter insertion, followed by SEMS deployment ([ Video 1 ]). Fluoroscopy confirmed appropriate stent positioning, with immediate clinical improvement. Fig. 4 The conventional endoscopic stent placement showing pronounced duodenal peristalsis with poor visualization and unstable positioning. Fig. 5 Continuous water instillation suppresses peristalsis, improves visualization, and enables successful SEMS deployment. Video 1 Underwater SEMS placement successfully relieves complex extrinsic duodenal obstruction after failed conventional stenting. Download Video To our knowledge, this is the first reported case of underwater endoscopic stent placement for malignant obstruction. This case demonstrates that the underwater technique, which uses continuous irrigation to suppress peristalsis and enhance visualization, may provide a feasible solution for navigating complex malignant obstructions that are difficult to access with standard endoscopic or fluoroscopic approaches. Endoscopy_UCTN_Code_TTT_1AO_2AZ Publication History Received: 09 May 2026 Accepted after revision: 23 June 2026 Article published online: 04 August 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/). Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany