Chronic rhinosinusitis is a very common condition, affecting 35 million Americans each year. All paranasal sinuses need ventilation to prevent infection and inflammation. Sinus ventilation occurs through the ostia into the nose. When rhinosinusitis occurs, the mucous membranes of the sinuses become swollen, resulting in ostia closure. Functional endoscopic sinus surgery (FESS) is a minimally invasive surgical procedure that opens the sinus ostia.