Enclosed with the information you will receive about your procedure, there is a review of the potential complications of your specific procedure. Overall, upper endoscopy and colonoscopy are very safe. There is a very small chance of allergic reaction to the medications used for sedation, over sedation that could compromise your breathing, bleeding, or perforation.
Bleeding can occur after a biopsy or removal of a polyp. It is usually minimal though rarely there can be major bleeding that could require hospitalization, blood transfusion, or surgery.Perforation (causing a tear in the wall of the esophagus, stomach, or intestine) is a very rare complication, though when occurs usually requires surgery.
If you have concerns about the possible complications of your procedure, please discuss this with your doctor.