Introduction

Histopathology remains the gold standard for the assessment of diminutive (≤5 mm) colorectal polyps, but it requires considerable cost and resources allocation. Optical diagnosis supported by artificial intelligence (AI) has shown promise, though its integration into clinical decision-making is limited. Our prior work showed the feasibility of replacing histopathology with AI-assisted human optical diagnosis in real-time practice.¹

Aims & Methods

This study aimed to assess patient acceptance, and diagnostic performance of autonomous computer-aided optical diagnosis (CADx) when used as the sole determinant in resect-and-discard (RD) and diagnose-and-leave (DL) strategies.
This prospective study was conducted at the University of Montreal Hospital Center between August and November 2024 (ID: CER23.095, NCT06059378). Consecutive patients aged 45–80 years undergoing elective colonoscopy were approached and provided detailed information about the use of CADx, and the principles of the RD and DL strategies. For consented patients, procedures were performed using CADEYE system, which autonomously provided an optical diagnosis for detected diminutive polyps. Lesions predicted to be neoplastic were removed and discarded without histopathologic analysis (RD), while rectosigmoid lesions predicted to be hyperplastic were left in place (DL). All colonoscopies were video-recorded. To establish the reference standard, the videos of all polyps undergoing optical diagnosis were independently reviewed by two expert endoscopists. In cases of disagreement, a third reviewer arbitrated the final decision. The primary outcome was the proportion of patients consenting to undergo autonomous CADx. Secondary outcomes included the accuracy of the RD strategy, the negative predictive value (NPV) of the DL approach, and the agreement between CADx- and expert-driven surveillance interval recommendations.

Results

95/102 patients approached (93.1%) consented to undergo CADx-based optical diagnosis (mean age 65.7 years). Among 149 diminutive polyps detected (51 (34.2%) in the rectosigmoid and 98 (65.8%) in the proximal colon), CADx provided optical diagnosis in 98.7% (n=147) of cases. The RD and DL strategies were applied to 113 (76.9%) and 30 (20.4%) of polyps, respectively. After excluding indeterminate cases (n=5) and sessile serrated lesions (SSLs) (n=14), the RD strategy achieved an accuracy of 83.5% and the DL strategy demonstrated a NPV of 92.3%. Surveillance interval agreement between CADx and expert recommendations was 100% (95%CI 96.2-100.0). Sensitivity analyses showed reduced performance when SSLs were classified as neoplastic, but Preservation and Incorporation of Valuable Endoscopic Innovations (PIVI) benchmarks were met when SSLs were considered hyperplastic.

Table 1. Diagnostic performance of computer- assisted optical diagnosis (CADx), using expert optical diagnosis as the reference.

Conclusion

Autonomous CADx achieved high patient acceptance and met key performance benchmarks for managing diminutive polyps using RD and DL strategies. These findings support its potential for safe, real-world implementation, though further development is needed to address current limitations in SSL detection and to enable quality optical diagnosis practice.

References

1. Taghiakbari M, Rex DK, Pohl H, et al. Pragmatic Resect and Discard Implementation Using Computer-Assisted Optical Polyp Diagnosis. Gastroenterology 2025;168:154-156.e2.

Disclosure

Daniel von Renteln has received research funding from ERBE Elektromedizin GmbH, Ventage, Pendopharm, Fujifilm and Pentax, and has received consultant or speaker fees from Boston Scientific Inc., ERBE Elektromedizin GmbH, and Pendopharm. Roupen Djinbachian has received speaker fees from Fujifilm. The remaining authors declare that they have no conflict of interest.

Introduction

Endoscopic Submucosal Dissection (ESD) is the best endoscopic technique that enables en bloc resection of superficial colorectal neoplasms.Despite its effectiveness, ESD is not very widespread in Western countries due to technical complexity, long procedure times, and a steep learning curve. These barriers have created a significant gap in adoption and outcomes between Eastern and Western centers. Underwater ESD (U-ESD) has been introduced to simplify the procedure. This study aimed to evaluate the effectiveness of U-ESD versus conventional gas-based ESD (G-ESD) in a Western center, focusing on procedural efficiency and safety.

Aims & Methods

This is a single-center, prospective randomized controlled trial conducted at Fondazione Campus Bio-Medico in Rome between December 2024 and April 2025.Forty patients with non-pedunculated colorectal lesions were randomly assigned in a 1:1 ratio to undergo either Underwater ESD (U-ESD) or conventional ESD with insufflation of Carbon Dioxide (CO2) (G-ESD).The primary outcome was total procedure time. Secondary outcomes included dissection speed, en bloc and R0 resection rates, use of hemostatic forceps, and the incidence of adverse events such as delayed bleeding, perforation, and post-ESD coagulation syndrome (PECS).

Results

A total of 40 patients referred to our endoscopic unit for ESD between December 2024 and April 2025. The mean size of the colorectal lesions was 57.4 mm and 40.7 mm in the U-ESD and G-ESD groups. The location of the lesions was in the rectum in 15% and 55% of the U-ESD and C-ESD groups, respectively; in the right side of the colon in 35% and 20% of the U-ESD and G-ESD groups, respectively. The morphology of LST was classified as LST-nongranular in 20 % and 25% of the U-ESD and G-ESD groups, respectively; as LST granular in 60% and 35% of the U-ESD and G-ESD groups, respectively. Fibrosis (grade 1 and 2) was present in 45% and 30% of the U-ESD and G-ESD groups, respectively. The mean total procedure time was shorter in the U-ESD group compared with the G-ESD group (53.3 ±33 minutes vs 78.7 ± 25.6 minutes; mean difference,–25.4 minutes; P=0.009).Mean dissection speed was faster in the U-ESD group compared with the G-ESD group (42 ± 26.3 mm2/min vs 13.3 ± 8 mm2/min; mean difference, 28.7 mm2/min; P= 0.001). En bloc and R0 resection rates in both groups were 100%. The use of a hemostatic forceps was significantly lower in U-ESD compared G-ESD (40% vs 90%, P= 0.001). Delayed bleeding occurred in only one patient in G-ESD group and was managed successfully by endoscopic clipping. No perforations occurred in either group. PECS was noted in only one patient in the G-ESD group.

Conclusion

UESD has shown a significantly shorter procedure time and faster dissection speed compared with GESD. These both empower the possibility of considering U-ESD as the preferred colorectal ESD method for colorectal lesions.