The target sign: an endoscopic marker for the resection of the muscularis propria and potential perforation during colonic endoscopic mucosal resection

Background: EMR of large sessile polyps and laterally spreading tumors (LSTs) of the colon is safe and cost-effective. Perforation remains a feared and well-recognized complication; however, endoscopic detection is often absent, and most commonly, diagnosis is delayed and depends on clinical signs and/or radiology findings. To date, an endoscopic sign to identify muscularis propria (MP) resection and potential perforation has not been described.

Objective: To describe an endoscopic sign for prompt recognition of EMR-related MP resection.

Design: Prospective analysis.

Settings: Tertiary referral academic gastroenterology unit.

Patients: Patients with the target sign were identified prospectively in 2 large prospective studies of EMR for colonic LSTs 20 mm or larger.

Intervention: A standardized EMR approach was used. MP defects were closed endoscopically with clips.

Main outcome measurements: The presence or absence of the target sign in the polypectomy specimen and its influence on subsequent endoscopic management of polypectomy complications.

Results: A total of 445 patients with LSTs or sessile polyps 20 mm or larger (mean size 33 mm, range 20-85 mm) were prospectively enrolled in 2 studies. Ten patients (mean age 70.3 years, range 48-83 years, 50% male) with target lesions and histologically confirmed MP resection were identified prospectively at the time of EMR, with 3 having full-thickness resection. All cases were identified intraprocedurally by a target sign on the underside of the specimen and a mirror target evident in the mucosal defect. All patients were treated endoscopically with 1 to 5 endoscopic clips. None required operative management. Thirteen inpatient days were required to treat the 10 patients (mean 1.3 days).

Limitations: Nonrandomized study.

Conclusions: Careful analysis of the post-EMR specimen and resection defect may reveal a target sign, an easily recognized and reliable marker of either partial- or full-thickness MP resection and potential perforation. Prompt recognition of this sign facilitates endoscopic management.