Introduction

Operator dexterity is recognised as a critical determinant of outcomes after surgery (1,2). No objective metric exists for the quality of endoscope tip manipulation (tip-control). We aimed to validate a tip control score in-vivo, using post endoscopic mucosal resection (EMR) snare tip soft coagulation (STSC) of the defect margin.

Aims & Methods

A web application containing a timed-score was used to record correct and incorrect applications (=hits) of STSC to the margin of defects after piecemeal EMR. Correct hits were visualised diathermy applications touching the defect margin.
2 blinded endoscopists scored sequential videos of STSC performed by consenting endoscopists. Correct hits/incorrect hits (=accuracy) and correct hits/second (=speed) were determined. Results were stratified by polypectomy complexity (SMSA[+] score)(3,4), difficulty of STSC application (independent movement of the colonic wall not explained by the movements of the endoscope [=movement artefact]) and experience of the endoscopist (expert vs fellows in endoscopy).

Results

39 STSC procedures performed by 10 endoscopists (3 experts, 7 fellows) were rated. 12 (30.8%) polyps were SMSA 2 or 3, 3 (7.7%) were SMSA 4, and 24 (61.5%) were SMSA+. 24 (61.5%) STSC procedures were categorised as difficult.
Median accuracy of STSC was 86.0% (interquartile range [IQR] 19.5, 95% confidence interval [CI] 77.0-91.0) and median speed was 0.175 (IQR 0.113, 95%CI 0.130-0.210). Accuracy strongly correlated with blinded expert impression of the tip-control demonstrated in the video (correlation coefficient=0.81, P<.001). Movement artefact significantly adversely impacted both overall accuracy (P=.06) and speed (P=.05). Increasing SMSA score adversely impacted overall accuracy (SMSA 4 vs SMSA+, P=.04), but not speed (P=.61).
Fellows were significantly less accurate (76.5% vs 92.0%, P<.001) and slower (0.155 vs 0.202 hits/s, P=.02) vs experts in applying STSC. Movement artefact significantly impacted the performance of fellows (accuracy 68% vs 88%, P=.036, 0.151 vs 0.213 hits/s, P=.07) but not experts (P=.281 and P=.483). In procedures without movement artefact, performance of fellows and experts were similar (accuracy P=.106, speed P=.148). In SMSA+ polyp observations with movement artefact fellows were significantly less accurate than experts (80.0% vs 92.0%, P=.045) (table 1).

		Median Accuracy % (IQR) [95% CI]			Median Correct Hits/s (IQR) [95% CI]
		Fellow	Expert	p	Fellow	Expert	p
Overall	Overall	76.5% (21.5) [70.9 -82.1]	92.0% (10.0) [88.2- 95.8]	<0.001	0.155 (0.078) [0.128-0.183]	0.202 (0.241) [0.109-0.294]	0.02
Easy* Difficult**	Overall	88.0% (11.5) [80.8-95.2] 68.0% (19.0) [61.1-74.9]	94.0% (12.8) [88.3-99.7] 92% (12.0) [86.9-97.1]	0.106 0.003	0.213 (0.083) [0.162-0.265] 0.151 (0.073) [0.125-0.177]	0.324 (0.258) [0.189-0.460] 0.198 (0.125) [0.070-0.327]	0.148 0.028
	p	0.036	0.281		0.070	0.483
Easy* Difficult**	SMSA 2+3	84.0% (10.0) [72.6-95.5] 67.0% (26.0) [51.3-82.7]	88.5% (11.5) [66.0-100.0] 82.0% (10.0) [62.4-100.0]	0.773 0.333	0.237 (0.064) [0.165-0.310] 0.151 (0.093) [0.100-0.207]	0.488 (0.187) [0.122-0.854] 0.407 (0.295) [0.000-0.985]	0.149 0.561
	p	0.371	0.700		0.074	1
Easy* Difficult**	SMSA 4	NA 68.0% (5.5) [61.8-74.2]	NA NA	NA NA	NA 0.175 (0.046) [0.121-0.229]	NA NA	NA NA
Easy* Difficult**	SMSA +	88.5% (6.5) [77.7-99.3] 80.0% (18.0) [70.9-89.4]	94.0% (9.0) [89.0-99.0] 92.0% (9.0) [87.0-97.0]	0.240 0.045	0.173 (0.096) [0.107-0.138] 0.121 (0.060) [0.089-0.153]	0.267 (0.245) [0.136-0.398] 0.198 (0.071) [0.082-0.314]	0.337 0.062
	p	0.111	0.405		0.540	0.768

Table 1 Median accuracy and speed for fellows vs experts stratified by SMSA level and difficulty. IQR, Interquartile Range; CI, Confidence Interval; *Easy, no movement artefact; **difficult, movement artefact; SMSA, Size-Morphology-Site-Access score.

Conclusion

This is the first in-vivo description of a score for the quality of endoscope tip manipulation. Endoscopist accuracy and correct hits/second were inversely related to training status, polypectomy difficulty and degree of movement artefact when applying STSC.
The score ranges presented here could be used to benchmark endoscopists and fellows with respect to SMSA scores, guide progression through SMSA levels and correct tip-control scores for movement artefact due to patient breathing.

References

1. Fecso AB, Szasz P, Kerezov G, Grantcharov TP. The Effect of Technical Performance on Patient Outcomes in Surgery: A Systematic Review. Ann Surg. 2017 Mar;265(3):492-501. doi: 10.1097/SLA.0000000000001959. PMID: 27537534.
2. Goldenberg MG, Garbens A, Szasz P, Hauer T, Grantcharov TP. Systematic review to establish absolute standards for technical performance in surgery. Br J Surg. 2017 Jan;104(1):13-21. doi: 10.1002/bjs.10313. Epub 2016 Sep 30. PMID: 27686465.
3. Gupta S, Miskovic D, Bhandari P et al. A novel method for determining the difficulty of colonoscopic polypectomy. Frontline Gastroenterology 2013; 4: 244-248.
4. Sidhu M, Tate DJ, Desomer L et al. SMSA-EMR score is a novel endoscopic risk assessment tool for predicting critical endoscopic mucosal resection outcomes Gastrointestinal endoscopy 2018; 87: AB467--AB468.

Disclosure

David James Tate consulting fees and research support from Olympus Medical. The remaining authors have no competing interests to disclose.

Introduction

Hot endoscopic mucosal resection (H-EMR) is the standard of care for large non-pedunculated colorectal polyps (LNPCPs) without suspicion of submucosal invasion, achieving low recurrence rates after en bloc resection or piecemeal resection with margin ablation in expert centers.^1,2 However, electrocautery is also responsible for complications which can lead to significant morbidity and necessitate additional invasive procedures.^3,4 Cold snare polypectomy (CSP) has proven to be preferable to H-EMR for adenomas ≤10mm and non-dysplastic sessile serrated lesions, providing comparable efficacy with improved safety, shorter procedural time and lower costs.⁵ These advantages have driven interest in expanding CSP to larger polyps.

Aims & Methods

This meta-analysis of randomized controlled trials (RCTs) aimed to compare the risk of recurrence and adverse events between cold snare polypectomy (CSP) and hot-endoscopic mucosal resection (H-EMR) for large non-pedunculated colorectal polyps (LNPCPs).
A systematic search of Medline, Embase and Cochrane Library databases was performed through August 2024 for studies comparing recurrence, bleeding and perforation rates between CSP and H-EMR for LNPCPs ≥15mm (PROSPERO ID: CRD42024568272). RCTs were included in the quantitative analysis. A random-effects meta-analysis, with heterogeneity measured with I², was conducted to generate pooled risk ratios (RR) with 95% confidence intervals.

Results

Four RCTs comprising 1516 LNPCPs (766 CSP and 750 H-EMR) in 1442 patients were included in the quantitative analysis. CSP demonstrated a higher recurrence risk at first surveillance colonoscopy than H-EMR in the pooled analysis (22.6% vs. 10.8%; RR=1.98; 95% CI: 1.22–3.21; p=0.02; moderate-certainty evidence), corresponding to a number needed to harm of 9. Regarding adverse events, CSP demonstrated a 67% reduced risk of delayed bleeding (1.2% vs. 3.9%; RR=0.33; 95% CI: 0.12-0.89; p=0.03; high-certainty evidence), corresponding to a number needed to treat of 37. Although CSP appeared to reduce the risk of intraprocedural bleeding (10.0% vs. 19.8%; RR=0.30, 95% CI: 0-52256.34, p=0.42), the wide confidence interval from the random-effects model included 1. There were no intraprocedural or delayed perforations in the CSP group.

Author	Study design	Number of patients		Age, mean (SD), years	Female, %	Number of LNPCPs		LNPCP size, mean/median (SD/IQR), mm	Right Location, %		Adenomatous histology, %
		CSP	H-EMR			CSP	H-EMR		CSP	H-EMR	CSP	H-EMR
O’ Sullivan T. et al., 2024	Single center, RCT	87	90	68.2 (10.0)	46.9	87	90	30 (25-35)	96.5	86.7	100	100
Steinbrück et al., 2024	Multicenter, RCT	184	192	65.9 (10.5)	48.2	193	203	30.1 (10.2)	88.1	86.2	60.7	68.5
Pohl H. et al., 2024	Multicenter, RCT	336	324	65.3 (10.2)	47.7	371	343	30 (25.4)	82.5	83.4	NR	NR
Nogales et al., 2023	Multicenter, RCT	115	114	67.9 (10.6)	43.3	115	114	25 (22-30)	80.0	78.1	71.9	77.2

Table 1. Patients, LNPCPs and procedure characteristics of the randomized controlled trials included in the quantitative analysis. (List of abbreviations: CSP, cold snare polypectomy; H-EMR, hot endoscopic mucosal resection; IQR, interquartile range; LNPCPs, large non-pedunculated colorectal polyps; NR, not reported; SD, standard deviation; RCT, randomized controlled trial)

Conclusion

CSP has nearly double the recurrence risk of H-EMR for LNPCPs. However, its superior safety profile may make it a preferable option for patients where procedural safety is prioritized over radicality, such as those with extensive comorbidities.

References

1. Ferlitsch M, Hassan C, Bisschops R et al. Colorectal polypectomy and endoscopic mucosal resection: European Society of Gastrointestinal Endoscopy (ESGE) Guideline - Update 2024. Endoscopy 2024; 56: 516-545. doi:10.1055/a-2304-3219
2. Kaltenbach T, Anderson JC, Burke CA et al. Endoscopic Removal of Colorectal Lesions: Recommendations by the US Multi-Society Task Force on Colorectal Cancer. Am J Gastroenterol 2020; 115: 435-464. doi:10.14309/ajg.0000000000000555
3. Sidhu M, Shahidi N, Gupta S et al. Outcomes of Thermal Ablation of the Mucosal Defect Margin After Endoscopic Mucosal Resection: A Prospective, International, Multicenter Trial of 1000 Large Nonpedunculated Colorectal Polyps. Gastroenterology 2021; 161: 163-170.e163. doi:10.1053/j.gastro.2021.03.044
4. Meulen LWT, Bogie RMM, Winkens B et al. Thermal ablation of mucosal defect margins to prevent local recurrence of large colorectal polyps: a systematic review and meta-analysis. Endosc Int Open 2022; 10: E1127-e1135. doi:10.1055/a-1869-2446
5. Rex DK, Anderson JC, Pohl H et al. Cold versus hot snare resection with or without submucosal injection of 6- to 15-mm colorectal polyps: a randomized controlled trial. Gastrointest Endosc 2022; 96: 330-338. doi:10.1016/j.gie.2022.03.006

Introduction

Operator dexterity is recognised as a critical determinant of outcomes after surgery (1-2). No such recognition exists for the quality of endoscope tip manipulation (tip-control) and no objective measurement scale exists.

Aims & Methods

The aim of this study was to develop and validate a score for tip-control in an ex-vivo setting.
A web application containing a timed-score with clickable buttons to indicate correct and incorrect application of snare tip soft coagulation (STSC) was developed. The score was tested on a training model containing 4 shapes constructed from 1-4 identical circles (radius 1.4cm) connected at their mid-points drawn onto a single piece of cooked ham.
Endoscopists with varied profiles consented to video recording of their timed complete application of STSC (hits) to sequential circles using a gastroscope. Correct application was defined as any visualised diathermy application touching the marked lines. Median correct-hits/incorrect-hits (accuracy) and correct hits/second (speed) were determined by a single rater over the 4 recordings and stratified by shape and endoscopist demographics.

Results

22 endoscopists (8[36.4%] trainees, 6[27.3%] non-interventional consultant gastroenterologists and 8[36.4%] interventional endoscopists) participated.
Participant median accuracy was 82.0% (IQR17.5, 95%CI 77.0-85.0) and correct hits/second 0.141 (IQR0.095, 95%CI 0.120-0.160). Accuracy strongly correlated with blinded rater opinion of the macroscopic ham appearance (correlation coefficient=0.78, P<.001).
A scatter plot of endoscopist accuracy versus correct hits/second categorized endoscopists into 4 groups (combinations of accurate/inaccurate, fast/slow)(Figure 1). Interventional endoscopists were commonly fast and accurate (accuracy 88.0%[P=.001], correct hits 0.191/s[P=.04]) versus other participants. Non-interventional consultants had the lowest accuracy numerically and statistically similar tip-control to other participants (accuracy 69.0%[P=.15], correct hits 0.135/s[P=.97])(inaccurate). Trainees had similar accuracy to non-trainees but lower correct hits/second (accuracy 73.6%[P=.25], correct hits 0.153/s [P=.03])(slow). Endoscopists with >5 years experience did not have better tip-control (accuracy 88.0%[P=.07], correct hits 0.132/s[P=.36]) when compared to the rest of the participants (table 1).

	Median Accuracy Group of Interest (IQR) [95%CI]	Median Accuracy Remaining population (IQR) [95%CI]	P	On Target Hits / second Group of Interest (IQR) [95%CI]	On Target Hits / second Remaining population (IQR) [95%CI]	P
Overall	82.0 (17.5) [77.0-85.0]	-	-	0.141 (0.095) [0.120-0.160]	-	-
Trainee	73.6% (8.1) [67.6-79.6]	85.5 (16.9) [79.6-91.4]	0.25	0.114 (0.046) [0.078-0.150]	0.153 (0.078) [0.097-0.209]	0.03
Consultant - not interventionalist	69.0% (15.8) [59.0-79.0]	81.8 (15.0) [77.2-86.3]	0.15	0.138 (0.028) [0.113-0.162]	0.135 (0.110) [0.081-0.190]	0.97
Consultant - interventionalist	88.0% (5.8) [83.9-92.1]	72.1 (14.7) [66.8-77.4]	0.01	0.191 (0.128) [0.102-0.280]	0.125 (0.07) [0.102-0.147]	0.04
>1000 colonoscopies	85.5% (10.8) [79.6-91.4]	72.5 (9.3) [66.8-78.2]	0.09	0.157 (0.092) [0.097-0.217]	0.114 (0.056) [0.082-0.146]	0.04
>5 years experience	88.0% (5.19) [79.9-96.1]	76.0 (14.5) [71.2-80.8]	0.07	0.151 (0.077) [0.070-0.232]	0.132 (0.061) [0.085-0.178]	0.36

Table 1 Comparison of the median tip-control accuracy and the on target per second per participants groups. CI, Confidence Interval; IQR, Interquartile Range; P, P-value; SMSA, size-morphology-site-access score for determining level of complexity of polypectomy; pEMR, piecemeal endoscopic mucosal resection.

Conclusion

This is the first demonstration of an ex-vivo objective tool to assess the quality of endoscopic tip manipulation. Tip-control reliably stratifies endoscopists by important demographics including interventional profile, number of polypectomies performed and those performing difficult polypectomy but does not correlate with years of endoscopy experience.
If tip-control can be linked to established performance indicators it may provide an objective benchmark for endoscopy and interventional procedures allowing tracking of progress over time.

References

1. Fecso AB, Szasz P, Kerezov G, Grantcharov TP. The Effect of Technical Performance on Patient Outcomes in Surgery: A Systematic Review. Ann Surg. 2017 Mar;265(3):492-501. doi: 10.1097/SLA.0000000000001959. PMID: 27537534.
2. Goldenberg MG, Garbens A, Szasz P, Hauer T, Grantcharov TP. Systematic review to establish absolute standards for technical performance in surgery. Br J Surg. 2017 Jan;104(1):13-21. doi: 10.1002/bjs.10313. Epub 2016 Sep 30. PMID: 27686465.

Disclosure

David James Tate consulting fees and research support from Olympus Medical. The remaining authors have no competing interests to disclose.

Introduction

There are no objective performance metrics for basic endoscopic skills to guide training and career trajectory. The fidelity of endoscopic tip manipulation is a key skill akin to hand steadiness in surgery. Two recent studies using ex-vivo¹ and in-vivo² models of snare tip soft coagulation (STSC) applied to a polypectomy defect margin reliably stratified endoscopists by interventional profile, number, and complexity of polypectomies performed.

Aims & Methods

Tip-control of endoscopists with varied expertise was assessed using a STSC model containing 3D-printed figures constructed from 1-4 perfect intersecting circles (radius=17.2mm) (shape 1=1 circle, shape 4=4 circles) printed onto the centre of a single piece of cooked ham. The study consisted of two assessments (=all 4 shapes, maximum 5 minutes/shape), 1 initial, two sessions of training on the model, and a second final after the training. Videos of assessments were rated via a web application for accuracy and speed (=correct hits/second) by 6 blinded raters in a random order using a web application. Each video was rated three times by three different raters. Accuracy and speed were determined and mutated into a composite-score (TIP-score) using Z-score normalization (score-mean/sd), added together with the addition of 5 to the result removing negative values.

Results

13 endoscopists participated (1 expert, 7 endoscopy fellows, 5 trainees) performing 8 procedures each. 312 assessments of 104 STSC videos were performed. Overall median speed [pre 0.25 vs. post 0.34 correct hits/sec; P<0.001] and TIP-score [pre 4.6 vs. post 5.4; P<0.001] were significantly increased after training but accuracy was not [pre 93.8% vs. post 94.7; P=0.1].

Fellows had an overall accuracy of 94.2% (vs. 97.6% expert [P <0.001], vs. 94.1% trainees [P <0.31]), a speed of 0.29 correct hits/sec (vs. 0.55 expert [P <0.001], vs. 0.27 trainees [P <0.001]), and a TIP-score of 5.05 (vs. 7.1% expert [P <0.001], vs. 4.9% trainees [P <0.02]). The expert showed worse accuracy (P=.006), and no change in speed (P=.1) or TIP-score (P=.9) post-training.

Fellows and trainees showed no change in accuracy (P=.06, .10) but significantly increased speed (both P<.001) and TIP-score (both P<.001) post-training. Compared to trainees and fellows the expert was more accurate than fellows and trainees pre-training (P<.001) but not post- (P=.40).

Expert speed and TIP-scores were significantly superior to trainees (all P<.001) and fellows (all P<.001) in both pre- and post-training. Fellows were significantly superior to trainees in speed pre+post (P=.03 & <.001) and TIP-score only post-training (P=.05). The expert showed a significant decrease in accuracy pre- vs post- readings indicating that performance can vary in a single individual at different time points.

	PRE	POST		PRE	POST		PRE	post
	ACCURACY % (IQR)	ACCURACY % (IQR)	P	SPEED correct hits/s (IQR)	SPEED correct hits/s (IQR)	P	TIP-score (IQR)	TIP-score (IQR)	P ​
Overall	93.8 (6.4)	94.7 (4.9)	.10	.25 (.10)	.34 (.16)	<.001	4.6 (1.7)	5.4 (1.7)	<.001
Expert	99.1 (1.9)	95.4 (3.1)	.006	.53 (.14)	.56 (.29)	.10	7.3 (1.3)	7.1 (1.6)	.90
Fellow	93.7 (6.5)	94.6 (5.8)	.06	.26 (.08)	.36 (.18)	<.001	4.7 (1.3)	5.4 (1.8)	<.001
Trainee	92.9 (5.1)	95.2 (5.5)	.10	.23 (.08)	.30 (.08)	<.001	4.3 (1.3)	5.2 (1.1)	<.001

Conclusion

An ex-vivo model to assess tip-control was found to stratify endoscopists by expertise. Furthermore, performing two structured training sessions using the model led to a significant increase in the tip-control of fellows, and trainees but not experts. These results have implications for standardising the assessment of endoscopic competency, benchmarking progress during training, and allowing expedited acquisition of complex endoscopic skills in an ex vivo setting.

References

¹ L.K. Debels, S. Smeets, P. Poortmans, V. Lala, C. Jorissen, T. Lamiroy, L. Desomer, R. Valori, J. Anderson, D.J. Tate. ENDOSCOPIC TIP CONTROL - A SIMPLE, EX-VIVO MODEL WITH POTENTIAL FOR ENDOSCOPIST BENCHMARKING AND TRACKING OF PROGRESS OVER TIME. UEG Week 2023; United European Gastroenterology Journal 2023; 11 (Supplement 8)
² L. Debels, S. Smeets, P.J. Poortmans, C. Jorissen, V. Lala, T. Lamiroy, R.Valori, L.Desomer, J. Anderson, D.J.Tate. (2023). THE ACCURACY OF SNARE TIP SOFT COAGULATION APPLIED TO THE MARGIN OF POST ENDOSCOPIC MUCOSAL RESECTION DEFECTS CORRELATES WITH ENDOSCOPIST POLYPECTOMY EXPERIENCE AND PROCEDURAL DIFFICULTY. Gastrointestinal Endoscopy. 97. AB211-AB212. 10.1016/j.gie.2023.04.354.

Disclosure

DJT: Pentax medical, Fujifilm, and Olympus research support and consulting.

Introduction

Endoscopic radical excision in the rectum may offer a curative, organ-preserving strategy, potentially reducing the need for surgery and its associated morbidity and mortality.¹ The muscle-retracting sign (MRS) detected using the pocket-detection method (PDM) has shown moderate to high diagnostic accuracy for real-time submucosal invasion (SMI) depth assessment in rectal lesions.² This study evaluated the technical and clinical outcomes of a structured algorithm combining PDM and MRS for real-time invasion depth assessment with endoscopic resection of rectal lesions.

Aims & Methods

We prospectively included consecutive patients with rectal lesions at risk of SMI at a tertiary care centre between September 2023 and March 2025. We excluded lesions with nodal metastases on radiological staging and subepithelial lesions. A management algorithm was applied, incorporating PDM for MRS status evaluation and invasion assessment, followed by endoscopic resection based on MRS status, lesion size, and location: endoscopic submucosal dissection (ESD; MRS-, all locations), endoscopic intermuscular dissection (EID; MRS+ or severe fibrosis, distal rectum), knife-assisted full-thickness resection (kFTR; MRS+ or severe fibrosis, any size, proximal extraperitoneal rectum), or device-assisted full-thickness resection (FTRD; MRS+ or severe fibrosis, ≤15 mm, intraperitoneal rectum). Primary outcomes were technical success, en-bloc and R0 resection and adverse events.

Results

37 rectal lesions were included (mean patient age 68.8 years [SD 10.1]; 56.8% male). The median lesion size was 30 mm (IQR 20–40), mostly located in the distal rectum (23/37; 62.2%), and distributed as anterior (n = 12), lateral (n = 11), and posterior (n = 14). 5 lesions (13.5%) were classified as JNET 2b, 15 (40.5%) as JNET 3.
Among MRS-negative lesions (23/37; 62.2%), 22 underwent ESD, and 1 underwent EID for submucosal fibrosis. In MRS-positive lesions (14/37; 37.8%), the selected treatments included EID in 7, kFTR in 6, and FTRD in 1.
Technical success of PDM and endoscopic resection was achieved in 36/37 cases (97.3%). En-bloc resection was achieved in 36/37 (97.3%) cases, and R0 resection in 34/36 (94.4 %). Pathology revealed deeply invasive (>pT1sm1) adenocarcinoma in 14/37 (37.8%), with 83.8% diagnostic accuracy of PDM + MRS. Curative resection was achieved in 26/37 cases (70.3%). Adverse events occurred in 4/37 patients (10.8%), including delayed bleeding in 3 (8.1%) and pneumonia in 1 (2.7%). No delayed perforation occurred. The median length of hospital stay was 1 day (IQR 1-1).
Rectal preservation was achieved in 34/37 patients (91.9%), with a median follow-up of 8.8 months (IQR 5.3-10.8). We observed no loco-regional recurrences, distant metastases, or deaths. Surgery was performed for technical failure in one case (kFTR aborted due to massive invasion, pT2N0 adenocarcinoma) and for non-curative resections in 2 cases (one with pT0N1 and another with pT0N0 in surgical specimens).

	ESD (n=22)	EID (n=8)	kFTR (n=6)
Technical success, n (%)	22 (100)	8 (100)	5 (83.3)
En-bloc, n (%)	22 (100)	8 (100)	5 (83.3)
Pathology, n (%) -LGD/HGD -pT1 sm1 -pT1 sm2-3 -pT2	17 (77.3) 2 (9.1) 3 (13.6) 0	3 (37.5) 1 (12.5) 3 (37.5) 1 (12.5)	0 0 4 (66.7) 2 (33.3)
R0, n (%)	21/22 (95.5)	8/8 (100)	4/5 (80)
Adverse events, n (%)	1 (4.5%)	1 (12.5)	1 (16.7)

Conclusion

The PRIME endoscopic algorithm demonstrated high technical success, en-bloc and R0 resection rates for rectal lesions at risk of SMI. This minimally invasive approach allowed rectal preservation in the majority of patients with a low rate of complications, making it a promising alternative to surgery for such lesions.

References

1. Argenziano, M.E.*, Sorge, A.*, Hoorens, A., Montori, M., Poortmans, P.J., Smeets, S., Tornai, T., Debels, L.K., Desomer, L. and Tate, D.J. (2025), Knife-assisted full-thickness resection guided by the pocket-detection method for posterior deeply invasive rectal cancer: A novel endoscopic approach (with video). DEN Open, 5: e70116. https://doi.org/10.1002/deo2.70116
2. Argenziano, M E*; Sorge, A*; Montori, M; Poortmans, P J; Tornai, T; Smeets, S; Al-Dury, S; Debels, L; Desomer, L; Tate, D J Accuracy of the Muscle Retraction Sign for determining deep Submucosal Invasion During Endoscopic Resection of Rectal Lesions. Endoscopy 2025; 57(S02): 14 - 14 DOI: 10.1055/s-0045-1805114

Introduction

Endoscopic mucosal resection (EMR) is a safe and effective method to resect large (>=20mm) non-pedunculated colorectal polyps (LNPCPs). Incorrect decision making regarding the endoscopic resection scar after EMR risks unrecognized residual or recurrent adenoma (RRA) propagating into post-colonoscopy colorectal cancer. Despite expert series suggesting that scar recognition and interrogation are well performed with a high negative predictive value(2), the performance of non-experts remains unknown.

Aims & Methods

We aimed to investigate the diagnostic performance of endoscopic imaging in detecting RRA at an endoscopic resection scar amongst non-experts and the impact of a learning intervention.
Methods: A survey containing 15 paired High-Definition White Light (HD-WL) and virtual chromoendoscopy (VC) images, a learning intervention on detection of RRA (LT), followed by 15 different HD-WL & VC images was circulated to the GIEQs foundation mailing list. Images were selected from a prospective database of surveillance after EMR. For each image the same questions were asked: Is this a resection scar? Is there evidence of RRA? What is your confidence? Demographic data collected included participant number of EMRs performed, current grade and years of experience. Comparisons were made to expert opinion derived at a consensus meeting of the senior authors regarding the appearances of the images using the approach set out in Desomer et al. 2017(2).

Results

82 participants completed the survey (response rate: 4.1%) resulting in 2,460 observations. 15 (18.3%) participants were experienced (performed >100 EMRs).

The overall accuracy of RRA detection pre-LT was 75.3% (95%CI 73.5-77.2) vs post-LT: 79.5% (95%CI 77.2-82.0, p =.006). Specificity significantly improved post-LT (50.0% [95%CI 44.1-55.4] pre vs 94.0% [95%CI 90.0-98.0] post, p<.001).

Both accuracy and specificity were significantly higher amongst experienced endoscopists (acc: 83.6% [95%CI 79.4-87.7], spec: 67.3% [95% CI 50.2-84.3]) versus inexperienced endoscopists (acc: 74.0% [95% CI 72.1-75.8], P<.001, spec: 46.7% [95% CI 41.1-52.3], P<.003) pre-LT. Specificity improved in both groups post-LT (experienced 67.3% [95%CI 50.2-84.3] vs 97.6% [95% 100-92.7], P<.001 and inexperienced 46.7% [95% CI 41.1-52.3] vs 93.5% [95% CI 88.3-98.7], P<.001). Furthermore the difference in specificity disappeared post-LT (spec experienced 97.6% [95% CI 100-92.7] vs inexperienced 93.5% (95% CI 88.3-98.7] p = .440).

	PRE learning intervention					POST learning intervention					P Overall PRE- vs POST -LT
	Experienced*	Inexperienced*	P*	Overall***		Experienced**	Inexperienced**	P**	Overall***
Accuracy (95% CI)	83.6% (79.4-87.7)	74.0% (72.1-75.8)	<.001	75.3% (73.5-77.2)		82.6% (77.6-87.7)	78.7% (75.9-81.7)	0.220	79.5% (77.2-82.0)		.006
Sensitivity (95% CI)	73.3% (64.9-81.7)	71.7% (68.6-74.8)	.650	72.0% (69.1-74.8)		75.0% (67.2-82.2)	69.8% (65.6-74.1)	0.300	70.9% (67.5-74.5)		.649
Specificity (95% CI)	67.3% (50.2-84.3)	46.7% (41.1-52.3)	.003	50.0% (44.1-55.4)		97.6% (100-92.7)	93.5% (88.3-98.7)	0.440	94.0% (90.0-98.0)		<.001
PPV (95% CI)	85.4% (78.1-92.8)	68.3% (65.2-71.3)	<.001	70.9% (67.8-74.0)		99.3% (100.0-97.7)	97.8% (96.4-99.3)	0.338	98.0% (99.1-98.0)		<.001
PPV (95% CI)	85.4% (78.1-92.8)	68.3% (65.2-71.3)	<.001	81.3% (80.0-83.0)		99.3% (100.0-97.7)	97.8% (96.4-99.3)	0.338	65.1% (62.1-68.1)		<.001

RRA smaller than 10 mm was more likely to be missed (<10mm: 77.5%, <5mm: 58.9% of missed detections). RRA occupying ≤20% of the scar accounted for two-thirds of missed detections (66.4%). RRA located on the edge of a scar (versus centrally) accounted for the vast majority of missed RRA (88.1%).

Conclusion

The accuracy of RRA detection in non-experts is low compared to previously published expert series, even amongst endoscopists performing EMR regularly. Low accuracy predominantly resulted from low specificity which was mitigated by the training intervention. These results suggest that the potential negative effects of missing RRA at an endoscopic resection scar (propagation between surveillance procedures and the potential for development of PCCRC) can be mitigated by training.

References

1. Michielan A, Merola E, Vieceli F, Rogger TM, Crispino F, Sartori C, et al. Recurrence rates after piecemeal endoscopic mucosal resection of large colorectal laterally spreading tumors. Ann Gastroenterol. 2023;36(2):195-202.
2. Desomer L, Tutticci N, Tate DJ, Williams SJ, McLeod D, Bourke MJ. A standardized imaging protocol is accurate in detecting recurrence after EMR. Gastrointestinal endoscopy. Department of Gastroenterology and Hepatology, Westmead Hospital, Sydney, New South Wales, Australia.: Elsevier, Inc.; 2017. p. 518-26.