The non-lifting sign is the suitability of large flat or sessile colorectal polyps for polypectomy by endoscopic mucosal resection (EMR). When fluid is injected under a polyp in preparation for endoscopic mucosal resection, some polyps do not "lift", indicating that the polyp is not separating from the submucosa. This makes polypectomy more technically difficult, and increases the risk of intestinal perforation if polypectomy is then attempted. It is also thought to be indicative of an early colorectal cancer that has invaded the submucosa significantly (sm3 – invasion down to the lower one third of the submucosa), which would make surgical removal of the tumour preferable to allow complete removal of the cancer. Consequently, the non-lifting sign is generally considered to be a contraindication to performing endoscopic mucosal resection.