The aim of this study is to compare the efficacy of underwater resection (polypectomy) versus conventional polypectomy techniques for small and large colorectal lesions identified during colonoscopy.

Conventional endoscopic resection of small and large (≥1cm) colorectal lesions is well established and performed with the colon fully distended with gas. Conventional polypectomy is effective, but the rate of incomplete resection is approximately 10%. Incomplete eradication of precancerous lesions contributes to interval colorectal cancer; therefore, alternative techniques for resection that safely and effectively increase the rate of complete resection are important. Underwater resection (UR) of benign colorectal lesions is a novel technique that utilizes the advantages of water aided endoscopic methods and may decrease the incomplete resection rate of small and large non-pedunculated lesions.

The investigators propose the hypothesis that small (6-9mm) and large (≥1cm) non-pedunculated neoplastic colorectal lesions resected by UR (partially distended, water filled lumen without submucosal fluid injection), will significantly decrease the incomplete resection rate (IRR) compared to conventional polypectomy performed in a gas distended lumen.

Small (6-9mm) and large (≥1cm) non-pedunculated benign neoplastic colorectal lesions identified during screening, surveillance, diagnostic or therapeutic colonoscopy will be randomized to conventional polypectomy (in a gas distended lumen with or without submucosal fluid injection) versus UR (partially distended, water filled lumen without submucosal injection) at the patient level. Small (6-9mm) lesions will be removed with a 9mm firm, thin wire cold snare and large (≥1cm) lesions will be removed by snare electrocautery. Efforts to remove lesions en bloc with a small rim of normal mucosa will be made, although some larger lesions (≥2cm) may require piecemeal resection. Submucosal fluid injection with a solution may be used with conventional techniques for large and/or flat lesions. Post-polypectomy incomplete resection rates will be assessed from 4 quadrant biopsies obtained around the resection site immediately post-resection.

Inclusion Criteria:

• Adult (≥18 years old) male and female patients.
• Scheduled for outpatient colonoscopy.
• Patient able to provide informed consent.
• Benign, small (6-9mm) and large (≥1cm) non-pedunculated colorectal lesions.

Exclusion Criteria:

• Diminutive (≤5mm) and pedunculated polyps.
• Lesions suspected of harboring deep submucosal invasion.
• Patients who decline to participate or are unable to provide informed consent.