To identify the abnormality, the physician uses an endoscope, a flexible tube with a light source, and a camera. Endoscopes are inserted through the mouth or rectum. An intravenous (IV) line will be started before the procedure begins to administer sedatives or anesthesia. The position you will be in is lying on your left side. Before, during, and after the procedure, your oxygen level, blood pressure, and pulse will be monitored continuously. A spray is used to numb your throat for upper endoscopies. To raise and buffer the lesion, a solution will be injected under and around the lesion once the endoscope is advanced to the lesion. Using various tools, the doctor will remove the tissue from the lesion and send it to the laboratory for testing. The procedure usually takes about 1-2 hours, but expect your visit to last an additional two to three hours to allow for pre-procedure preparation and follow-up.