Background: Colon cancer incidence is on the rise and despite having undergone a colonoscopy to screen and remove all visible polyps as a preventive measure, nearly 1 in 110 patients will develop colon cancer within 3 years. The three main possible explanations for this are missing polyps, incompletely removed polyps, or rapidly growing tumors. Objective: To determine the proportion of colonic polyps ≤ 3 cm in size that show evidence of residual polyp tissue following colonoscopy and polypectomy. Methods: Patients who presented for colonoscopy at a community center were invited to participate in this study. Those who had confirmed adenoma were invited to repeat the procedure in 2 to 6 months with biopsies at the resection site to check for the presence of residual polyp tissue. Exclusion criteria included the absence of adenoma in the resected lesion, contraindication to polypectomy or follow-up colonoscopy, refusal to participate in follow-up examination, and other conditions increasing colon cancer risk. If polyps between 5 mm and 30 mm were found, the endoscopist resected them using the hot snare polypectomy technique or endoscopic mucosal resection (EMR). Results: Ninety-one patients completed the study protocol, with 105 lesions being studied. The second procedure was performed between 2 and 24 months. All analyzed lesions were adenoma, and three of them were associated with intramucosal adenocarcinoma. Others included 60 tubular lesions, 37 tubulovillous lesions, and 5 serrated lesions. Thirty-two lesions were flat and were removed by EMR; polypectomy was performed for 73 lesions. There was no residual tissue in the polypectomy group. The EMR group presented three cases of incomplete resection without adenocarcinomas. Conclusion: Our study showed that flat lesions might be an important cause of incomplete resection. In addition, we documented the complete resection of pedunculated lesions in all studied patients. This study provides more evidence to validate the empirical perception in the medical field that assumes the complete resection of pedunculated polyps. Therefore, we suggest that patients who undergo snare removal of pedunculated polyps should follow the regular protocol for colon cancer screening, with colonoscopy every 5 to 10 years. Meanwhile, the surveillance scheme should be reviewed for patients who undergo removal of flat lesions smaller than 30 mm.