A colonoscopy poses few risks. Rarely, complications of a colonoscopy may include:
Adverse reaction to the sedative used during the exam Bleeding from the site where a tissue sample (biopsy) was taken or a polyp or other abnormal tissue was removed
A tear in the colon or rectum wall (perforation)
After discussing the risks of colonoscopy with you, your doctor will ask you to sign a consent form authorizing the procedure.