Endoscopy means looking inside and refers to looking inside the human body for medical reasons. (Endoscopy is also used in situations such as the inspection of nuclear fuel elements, where direct line-of-sight observation is not feasible.) It is a minimally invasive diagnostic medical procedure used to evaluate the interior surfaces of an organ by inserting a small scope in the body, often but not necessarily through a natural body opening. Through the scope, one is able to see lesions.