Endoscopic full-thickness resection of a rectal submucosal tumor with the double-tunnel bridge formation method: a case report

Endoscopic submucosal dissection (ESD) is a treatment option for colorectal epithelial lesions that enables en bloc resection of large or fibrotic lesions [ 1 ]. In Western countries, endoscopic full-thickness resection (EFTR) is often selected for difficult lesions, particularly those with severe fibrosis or non-lifting characteristics [ 2 ] [ 3 ]. In Japan, where ESD originated, several technical methods – such as the double-tunnel method and the bridge formation method (BFM) – have been developed to facilitate resection in challenging cases [ 4 ]. In addition, peranal endoscopic myectomy (PAEM) has recently emerged as a minimally invasive option for lesions involving the muscularis propria, highlighting the usefulness of double-tunnel creation for controlled myectomy [ 5 ]. Building on these advancements, we applied double-tunnel formation and BFM to EFTR to achieve precise dissection and safe full-thickness resection of deeply invasive submucosal tumors (SMTs). A 74-year-old woman was referred after a positive fecal immunochemical test. Colonoscopy revealed a rectal SMT, and both boring biopsy and endoscopic ultrasound (EUS)-guided fine-needle aspiration were non-diagnostic. EUS showed an 11-mm hypoechoic submucosal mass partially extending into the muscularis propria ([ Fig. 1 ]). Endoscopic resection was performed for diagnosis ([ Video 1 ]). Two submucosal tunnels were created, but the lesion was not visualized, suggesting deeper involvement ([ Fig. 2 ]). Inner circular muscle resection was initiated, and with the BFM approach, the overlying mucosa was preserved to provide natural traction and clarify the dissection plane [ 2 ]. The lesion penetrated the muscularis propria and was removed en bloc as a full-thickness specimen ([ Fig. 3 ], [ Fig. 4 ]). The defect was closed with a Mantis clip and additional standard clips, achieving secure ([ Fig. 5 ]) closure. The patient recovered uneventfully. Fig. 1 A 15-mm submucosal tumor located in the lower rectum. Endoscopic ultrasonography showing an 11-mm extramural hypoechoic lesion. Fig. 2 Wide mucosal incision and creation of two submucosal tunnels using the bridge formation method (BFM). Fig. 3 Full-thickness resection performed only at the area containing the tumor by utilizing natural traction. Fig. 4 Granulomatous inflammation observed in the SMT-like lesion. SMT, submucosal tumor. Fig. 5 Closure of the full-thickness defect using clips. Download Video DBFR-assisted endoscopic full-thickness resection of a rectal submucosal tumor, showing double-tunnel creation, natural traction using the mucosal bridge, selective full-thickness dissection, and clip closure of the defect. DBFR, double-tunnel bridge formation.Video 1 This novel technique, termed the double-tunnel bridge formation method-assisted EFTR (DBFR), offers three major advantages: (i) the double-tunnel approach limits the extent of muscle resection; (ii) BFM provides natural traction and a clear dissection plane without additional devices; and (iii) the limited full-thickness defect permits secure closure with clips. Endoscopy_UCTN_Code_TTT_1AQ_2AD_3AD Publication History Article published online: 05 March 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