This is a procedure that allows a physician to visualize the upper portion of the digestive tract, which is the esophagus, stomach and duodenum (first portion of the small intestine). It is performed for symptoms such as abdominal pain, nausea, vomiting, heartburn, or difficulty swallowing. Patients are typically sedated for this procedure. An endoscope is used, which is a long thin flexible tube with a light and camera at the end. Tools may be passed through the endoscope to obtain tissue samples. This is generally a very safe procedure, although rare complications can occur including bleeding, infections, or tearing of the digestive tract.