The surgery is performed endoscopically, so no external skin incision is needed. The surgeon performs the planned operation on the anatomical structures of the nose with the help of a special optical instrument, the endoscope, inserted through the nostrils, under the control of the eye. He opens the fibrous cells from the inside of the nose, removes diseased mucous membranes that are no longer able to heal themselves, including polyps if present, and frees and dilates the natural oral cavities of the paranasal sinuses. The surgeon operates with microsurgical instruments alongside the endoscope, and at the end of the operation, depending on the bleeding, a tampon may be placed in the nose, but this is not common. In a sinus endoscopy (sinuscopy), a thicker puncture instrument (trocar) is passed through the anterior or lateral (side) bony wall of the sinus, through which an endoscope can be inserted into the sinus.