Simple optical evaluation criteria reliably identify the post-endoscopic mucosal resection scar for benign large non-pedunculated colorectal polyps without tattoo placement.

Background: Recognition of the post-endoscopic mucosal resection (EMR) scar is critical for large (≥ 20 mm) non-pedunculated colorectal polyp (LNPCP) management. The utility of intraluminal tattooing to facilitate scar identification is unknown.

Methods: We evaluated the ability of simple easy-to-use optical evaluation criteria to detect the post-EMR scar, with or without tattoo placement, in a prospective observational cohort of LNPCPs referred for endoscopic resection. The primary outcome was scar identification, further stratified by lesion size (20-39 mm, ≥ 40 mm) and histopathology (adenomatous, serrated).

Results: 1023 LNPCPs underwent both successful EMR and first surveillance colonoscopy (median size 35 mm, IQR 30-50 mm); 124 (12.1 %) had an existing tattoo or a tattoo placed at the index EMR. The post-EMR scar was identified in 1020 patients (99.7 %). The presence of a tattoo did not affect scar identification (100.0 % vs. 99.7 %;  > 0.99). There was no difference for LNPCPs 20-39 mm, LNPCPs ≥ 40 mm, adenomatous LNPCPs, and serrated LNPCPs (all  > 0.99).

Conclusions: The post-EMR scar can be reliably identified with simple easy-to-use optical evaluation criteria, without the need for universal tattoo placement.