Studies report that almost 50% of Large Non-Pedunculated Colorectal Polyps (LNPCP) have been subjected to heavy manipulation in form of prior attempts at resection or extensive biopsy sampling prior to referral to an expert centre. This significantly impacts several critical outcomes of endoscopic resection (ER).  However, understanding of standardised classifications of LNPCP, endoscopic diagnosis and indications for ER has increased in general endoscopy practice which may have improved decision making prior to referral. We aimed to compare trends in patterns of prior injudicious manipulation and the significance of biopsy sampling over sequential time periods in a large cohort of patients referred to a tertiary referral centre for ER.

Referral documentation, including clinic and referral letters, endoscopy reports, and histopathology result, were reviewed for evidence of prior resection attempts or biopsy sampling. Data included the number of biopsy samples taken and corresponding histological results. Patients referred between January 2011 and August 2024 were categorised into five time periods. Heavy manipulation was defined as either a prior resection attempt or ≥6 biopsy samples. Analyses included comparisons of resection attempts, heavy manipulation, biopsy sampling, and the detection of high-grade dysplasia on biopsies (as a marker of improved lesion assessment and targeted sampling). Trends in practice changes were assessed using the Chi-square test for trend

1407 LNPCP were treated by ER. There was a significant trend toward fewer prior failed attempts at resection over sequential time periods with 30% in Period 1 and only 11% in Period 5 (p<0.001); fewer LNPCP subjected to heavy manipulation with 61% in Period 1 and 27% in Period 5 (p<0.001) and fewer LNPCP with prior biopsy sampling with 77% in Period 1 and 47% in Period 5 (p<0.001). However, there was no trend found for an improvement in biopsy sampling yields of HGD with 18% in Period 1 and 25% in Period 5 (p=0.1).

In a large cohort of ER of LNPCP, this study demonstrates a significant reduction over time in failed resection attempts, heavy manipulation, and biopsy sampling of LNPCP before referral to a tertiary centre for endoscopic resection (ER). This suggests an improvement in endoscopic lesion assessment and decision making by general endoscopists. However, heavy manipulation remains a significant problem. Although fewer LNPCP are biopsied prior to referral, the yield of significant findings did not change, suggesting biopsies are not effectively targeted, and highlighting the need for further improvements in lesion assessment.