These polyps are more difficult to remove endoscopically, and polypectomy in these cases has a higher risk of complication. Sessile polyps up to 10mm can often be removed by snare polypectomy. Polyps over 10mm may have to be removed piecemeal by snare polypectomy. The use of electrocautery over a large area has a significant risk of causing colonic perforation; to reduce this chance, and to facilitate the polypectomy, sterile fluid (saline or colloid, with methylene blue dye added) can be injected under the base of the polyp to raise it away from the muscular layers of the colon.
Pedunculated polyps can be removed by snare polypectomy. When the polyp is identified, a polypectomy snare is passed over the polyp and around the stalk of the polyp. The loop of the snare is then tightened to grip the polyp stalk, and the polyp is pulled away from the wall of the colon. An electric current is then passed through the snare loop to cut through the polyp stalk, while providing electrocautery at the same time. The polyp can then be retrieved using the snare, or an endoscopy basket, and removed by withdrawing the colonoscope.