Introduction The role of piecemeal endoscopic mucosal resection (p-EMR) for sessile/flat colonic polyps previously destined for surgery is expanding. However, surgery remains appropriate in some cases. The objectives of this study were to determine the primary reasons in this decision-making, and factors associated with polyp non-excision, and the presence of submucosal invasive cancer (SMIC).

Method A prospective observational cohort study of all polyps referred for consideration of p-EMR to our tertiary centre between January 2010 and August 2012 was performed. For each case, a detailed endoscopic evaluation of the polyp was performed prior to the polyp being excised or not excised. The primary reason for polyp non-excision was documented. Univariable and multivariable analyses were performed to determine factors associated with (i) non-excision and (ii) submucosal invasive cancer (SMIC).

Results Seventy-one of 419 (17%) polyps were not excised (p-EMR not attempted in 52/71 and abandoned in 19/71 cases). The primary reasons for non-excision were; suspected SMIC (36/71), polyp size +/- location, poor polyp access and patient comorbidities. On multivariate analysis, factors associated with polyp non-excision were increasing polyp size (p < 0.001), site (caecum and sigmoid colon, p < 0.001), surface features suggestive of SMIC (Paris IIc, Kudo V and NICE III, all p < 0.001) and female gender (p = 0.04). SMIC was present in 9% of polyps >2cm and was more prevalent in the rectum to the descending colon than in the transverse colon to caecum (p = 0.04). Although surface features were associated with SMIC on univariable analysis and the positive predictive values are relatively high (Paris IIc 80%, Kudo V 86% and NICE III 86%)., the sensitivity of these features for a diagnosis of SMIC were relatively low (Paris IIc 11%, Kudo V 49% and NICE III 51%).

Conclusion A percentage of polyps referred to a tertiary institution were not suitable for p-EMR, most commonly because of suspicion of SMIC. Specific surface features of malignancy may be present but the physician’s overall endoscopic evaluation was also useful in predicting suitability of polyps for p-EMR.

Disclosure of interest None Declared.