Background <p>Screening colonoscopy plays a critical role in reducing colorectal cancer incidence by identifying and removing polyps. Simple and safe treatment is the most common request of both doctors and patients. Cold snare polypectomy (CSP) is increasingly favored for polyps &lt; 10 mm, yet concerns remain regarding residual tissue. The aim of this study was to evaluate the efficacy and safety of CSP in the outpatient treatment of sessile polyps &lt; 10 mm using endoscopic optical assessment.</p> Methods <p>Patients undergoing outpatient screening colonoscopy who consented to combined polypectomy were recruited, excluding those on anticoagulants or antiplatelets. CSP was performed for detected sessile polyps &lt; 10 mm, and patients did not undergo any additional screening laboratory tests. Postoperative wounds were assessed endoscopically, and resected specimens were stained with crystalline violet for optimum pathological preparation and evaluation. Complete resection was determined separately. Complications and 7-day postoperative outcomes were recorded.</p> Results <p>A total of 194 sessile colorectal polyps &lt; 10 mm were resected from 77 patients, with a complete resection rate of 91.24% (95% confidence interval: 87.2–95.2%). There was a statistically significant difference in the rate of complete resection by endoscopic optical assessment compared to pathologic assessment (86.60% [168/194] vs. 72.68% [141/194], p &lt; 0.01). Optical assessment was not significantly different from the final total resection rate (86.60% [168/194] vs. 91.24% [177/194], p = 0.15). No adverse events occurred in all patients.</p> Conclusions <p>CSP is a safe and effective technique for outpatient resection of sessile polyps &lt; 10 mm. Optical assessment of postoperative defects provides a viable method for determining complete resection.</p> Trial registration <p>Trial registered at the Chinese Clinical Trial Registry (registration number: ChiCTR2400082461, registration date: 29/3/2024).</p>