Functional endoscopic sinus surgery (FESS) on the paranasal sinuses is a minimally invasive procedure to restore sinus drainage pathways and remove diseased tissue using an endoscope through the nostrils. You may need this intervention if you have chronic rhinosinusitis, polypoid growths, sinus cysts, or non-response to a long-term drug therapy. Under camera guidance, the surgeon carefully removes abnormal mucosa and polyps and opens blocked drainage pathways, restoring the sinuses' ability to naturally clear themselves. The surgery restores nasal breathing, relieves headache and nasal congestion, and significantly reduces the frequency of infection flare-ups.