The principle of this examination is to explore the interior of the body using an endoscope introduced by a natural orifice.

The endoscope or fibroscope consists of a flexible tube of a few millimeters in diameter in which is inserted an optical fiber. It has a light source at one of its ends. Some use a mini-camera and are connected to a video screen. They can be equipped with pliers to take samples for laboratory analysis. A control system makes it possible to go once inside the body.

The majority of fibroscopies are under general anesthesia.