The target sign: a new weapon for early diagnosis of colonic perforation during EMR.

Widespread use of screening colonoscopy has led to he identification and endoscopic resection of colonic polps. Even very large and flat polyps can now be successully removed endoscopically by using EMR and endocopic submucosal dissection techniques.1 Although very uccessful, these techniques can potentially cause serious, ven life-threatening complications. The article by Swan et al2 in the current issue of Gasrointestinal Endoscopy deals with the most serious comlication of EMR: perforation of the colonic wall. The uthors analyzed endoscopic treatment of 445 patients ith large ( 20 mm in diameter) laterally spreading umors and sessile colonic polyps. This analysis led to dentification of a new endoscopic marker of colonic erforation—the target sign. The authors used normal saline solution mixed with ndigo carmine for submucosal injection and gave the ollowing description of the target sign: “The resected muscularis propria] appears on the transected surface of he specimen as a white to gray central circular disk, ‘the arget,’ surrounded by a web of blue-stained submucosal onnective tissue (after submucosal injection), which is hen encircled by the white cauterized mucosa.” Although he authors emphasized the role of both colored solution or submucosal injection and the depth of resection in enerating the target sign, it seems that resection (full or artial) of the muscularis propria layer of the colonic wall ie, depth of resection) is far more important than the olution used to create a submucosal cushion: I have seen he target sign in cases of inadvertent resection of the uscularis propria even when normal saline solution ithout any colored additives was used for submucosal njection during colonic EMR (Fig. 1). How important is this newly described target sign for a racticing gastroenterologist? The target sign has very imortant clinical value. Colonic perforations have been reorted in 2% to 10% of patients undergoing colonic EMR nd endoscopic submucosal dissection.3-7 Most frequently, he perforation is suspected in patients reporting abdomnal pain after polypectomy and usually is confirmed by eritoneal signs on physical examination and the presence f free air on an abdominal radiograph or CT scan. How-