Specialty Surgeon Complete Packaged Procedure. Endoscopic Sinus Surgery (ENT) Functional Endoscopic Sinus Surgery (FESS) is a procedure providing direct visualization of nose and paranasal sinuses. It is a minimally invasive surgical procedure that opens up sinus air cells and sinus ostia (openings) with an endoscope.The purpose of FESS is to restore normal drainage of the sinuses associated with sinusitis. Treatment cost includes the facility fee, physician’s fee, related medical procedures and drugs required to administer the plan of care. Not included are diagnostic studies, consultations with additional specialists and cost of complication management; travel, food and lodging.