Simulation of a colorectal polypoid lesion-a pilot porcine model

Background: Large sessile polyps almost always contain villous tissue with appreciable premalignant potential and tend to recur locally after colonoscopic resection. Developing new endoscopic techniques for the removal of polyps requires a large animal model of colorectal polypoid lesions. So far, no appropriate large animal model of a colorectal or other GI polyp has been described in the English literature. Objective: Our purpose was to develop a large animal model simulating large, perfused and viable, sessile colorectal polypoid lesions, with distinct easily detectable histologic features. Setting: An animal laboratory. Interventions: Two simulated rectal polyps, using 2 different techniques, were created in each of 10 animals. The polyps were simulated by ovarian tissue that was introduced either intraluminally through the rectal wall or into a dissected submucosal space in the rectal wall. In 2 animals the created polyps were endoscopically resected. Results: All submucosal lesions were sessile-like polypoid lesions because the base of the polyp was the widest diameter of the lesion. All transmural polypoid lesions had short and thick pedicles. Resection by snaring and cutting was demonstrated to be feasible. Main Outcome Measurements: The mean measurements of the submucosal-simulated polyps were as follow: 1.74 cm (±0.32) × 2.07 cm (±0.42) × 1.51 cm (±0.27). The mean measurements of the transmural-simulated polyps were significantly larger: 2.55 cm (±0.52) × 3.57 cm (±1.1) × 2.7cm (±0.64). Limitation: This model does not simulate a real intestinal neoplasia. Conclusion: Either method, the submucosal or the transmural, could be helpful in the research and development efforts of surgical and endoscopic treatments of intestinal polyps.