The “double string” sign: a warning image after cold endoscopic mucosal resection
A 52-year-old man underwent screening colonoscopy. A sessile serrated lesion (Paris 0-Is, NICE-1; 17 mm diameter) was observed in the right colon. After submucosal injection with gelofusine plus indigo carmine, en bloc cold endoscopic mucosal resection (cold-EMR) was attempted using a 25-mm braided snare (SnareMaster SD-210U-25; Olympus, Tokyo, Japan) ([Fig. 1]). After snare closure, moderate traction of the snare sheath was applied to remove the lesion; however, the lesion remained trapped due to a large amount of tissue caught. The snare was repositioned slightly, and resection was successful. On inspection of the mucosal defect, the submucosal layer was observed with apparent “bubble sign” after waterjet irrigation ([Fig. 2 a], [Video 1]), followed by a “double string” sign, suggesting exposure of damaged muscle fibers ([Fig. 2 b]). After insufflation and water irrigation, these muscle fibers separated showing deep muscular injury with visible serosa ([Fig. 2 c]). The defect was immediately closed with endoscopic clips ([Fig. 2 d]). The patient was monitored for 4 hours and discharged with prophylactic antibiotics and no symptoms. No complications occurred. Histology confirmed a 21 × 12 × 2 mm specimen and suspicion of serrated lesion without dysplasia.
Video 1 The “double string” sign and perforation after cold endoscopic mucosal resection.
Colonic perforation after cold-EMR is infrequent    . The description of a new sign in the mucosal defect (“double string sign”) after cold-EMR should alert endoscopists to prevent delayed perforation. The sign refers to bundles of muscle fibers with loose disposition within the mucosal defect that indicates deep injury to the muscular layer. This is caused by a combination of snare closure and excessive traction applied to remove the tissue. The use of specifically designed snares for cold snare polypectomy with greater excision ability (without the need for traction of the snare sheath)  and tissue resections < 15 mm could decrease the risk of injury to the muscular layer during cold-EMR.
Endoscopy E-Videos is a free access online section, reporting on interesting cases and new techniques in gastroenterological endoscopy. All papers include a high
quality video and all contributions are
freely accessible online.
This section has its own submission
19 June 2020 (online)
© 2020. Thieme. All rights reserved.
Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany
- 1 Ferlitsch M, Moss A, Hassan C. et al. Colorectal polypectomy and endoscopic mucosal resection (EMR): European Society of Gastrointestinal Endoscopy (ESGE) Clinical Guideline. Endoscopy 2017; 49: 270-297
- 2 Paspatis GA, Dumonceau JM, Barthet M. et al. Diagnosis and management of iatrogenic endoscopic perforation: European Society of Gastrointestinal Endoscopy (ESGE) Position Statement. Endoscopy 2014; 46: 693-711
- 3 Rodriguez SanchezJ, Sánchez AlonsoM, Pellisé M. Bubble sign: detecting perforation after cold snare polypectomy. Endoscopy 2019; 51: 796-797
- 4 Chandrasekar VT, Spadaccini M, Aziz M. et al. Cold snare endoscopic resection of nonpedunculated colorectal polyps larger than 10mm: a systematic review and pooled analysis. Gastrointest Endosc 2019; 89: 929-936