Colonoscopy and polypectomy are safe and associated with very low risk when performed by physicians trained in Endoscopy. One possible complication is perforation, in which a tear through the wall of the bowel may allow leakage of intestinal fluids. This complication usually requires surgery, but may be managed with antibiotics and IV fluids in selected cases. Bleeding may occur from the biopsy or polyp site. It is usually minor and stops on its own or can be controlled by cauterization (application of electrical current) through the colonoscope. Rarely transfusions or surgery may be required. Local irritation of the vein may occur at the site of medication injection. A tender lump may develop, which may remain for several weeks to several months, but goes away eventually. Other risks include drug reactions and complications from unrelated diseases, such as heart attack or stroke. Death is extremely rare, but remains a remote possibility.