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What Is Functional Endoscopic Sinus Surgery?

Functional endoscopic sinus surgery is a minimally invasive operation that uses nasal endoscopes to open diseased sinus drainage pathways without external facial incisions. It is commonly abbreviated FESS and is also referred to more broadly as endoscopic sinus surgery. The surgeon removes selected obstructing tissue, polyps, diseased mucosa, or thin bone to enlarge natural sinus openings and improve ventilation and drainage. The extent of surgery is tailored to the patient's sinus disease rather than following one identical operation for every case.

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What Is Functional Endoscopic Sinus Surgery?

Functional endoscopic sinus surgery is a minimally invasive operation that uses nasal endoscopes to open diseased sinus drainage pathways without external facial incisions. It is commonly abbreviated FESS and is also referred to more broadly as endoscopic sinus surgery. The surgeon removes selected obstructing tissue, polyps, diseased mucosa, or thin bone to enlarge natural sinus openings and improve ventilation and drainage. The extent of surgery is tailored to the patient's sinus disease rather than following one identical operation for every case.

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Why Is Functional Endoscopic Sinus Surgery Performed?

FESS is commonly performed for chronic rhinosinusitis when symptoms, disease characteristics, quality-of-life burden, and prior treatment support surgery. It can be especially useful for chronic rhinosinusitis with nasal polyps, fungal disease, bony changes, or other disease that is unlikely to respond adequately to continued medical treatment alone. Computed tomography and nasal endoscopy help confirm disease and guide operative planning. Surgery is part of long-term disease management rather than a guarantee that chronic sinus inflammation will never recur.

How Is Functional Endoscopic Sinus Surgery Performed?

The surgeon passes a thin endoscope through the nostril to view the nasal cavity and sinus openings. Small instruments are used to enlarge selected natural drainage pathways and remove polyps, inflammatory tissue, fungal debris, or diseased bone when required. The maxillary, ethmoid, frontal, and sphenoid sinuses can be addressed individually according to the disease pattern. Image-guidance systems can be used in selected complex cases to help the surgeon relate the instruments to preoperative computed-tomography anatomy.

What Is Recovery Like After Functional Endoscopic Sinus Surgery?

Nasal congestion, mild bleeding, pressure, and crusting are common during early recovery. Saline irrigation and prescribed topical medical therapy are commonly used to keep the operated sinuses clean and support healing. Follow-up nasal endoscopy and debridement can be performed to remove crusts or secretions and assess the newly opened sinus cavities. Long-term treatment can still include nasal corticosteroids or other medical therapy because chronic rhinosinusitis can relapse after surgery.

What Are the Risks and Complications?

Possible complications include bleeding, infection, scar formation, persistent symptoms, recurrent polyps, and the need for revision surgery. Because the sinuses lie near the eye sockets and skull base, rare injuries can involve the orbit, eye muscles, optic nerve, or cerebrospinal fluid space. Cerebrospinal fluid leakage can lead to meningitis if not recognized and treated. Smell changes, tearing problems, numbness, or complications from anesthesia can also occur.

Frequently Asked Questions About Functional Endoscopic Sinus Surgery

Is FESS performed through the nostrils?

Yes. Standard endoscopic sinus surgery is performed through the nasal passages, so external facial incisions are usually not needed.

Does FESS cure chronic sinusitis permanently?

Not necessarily. Surgery improves sinus access and drainage, but chronic rhinosinusitis can recur and often still requires long-term medical management.

Is a CT scan used before sinus surgery?

Yes. Current surgical guidance recommends fine-cut computed tomography for operative planning in adults who are candidates for endoscopic sinus surgery.

Can nasal polyps return after FESS?

Yes. Polyps and inflammation can recur, particularly in chronic inflammatory disease, so ongoing topical therapy and follow-up are often needed.

References

Clinical Practice Guideline: Surgical Management of Chronic Rhinosinusitis. PubMed. https://pubmed.ncbi.nlm.nih.gov/40424072/. Date Accessed September 11, 2026.

CPG: Surgical Management of Chronic Rhinosinusitis. American Academy of Otolaryngology-Head and Neck Surgery. https://www.entnet.org/quality-practice/quality-products/clinical-practice-guidelines/cpg-surgical-management-of-chronic-rhinosinusitis/. Date Accessed September 11, 2026.

Chronic Sinusitis. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK441934/. Date Accessed September 11, 2026.

Sinus Endoscopic Surgery. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK563202/. Date Accessed September 11, 2026.

Complications in Endoscopic Sinus Surgery: A TriNetX Network Analysis. PubMed. https://pubmed.ncbi.nlm.nih.gov/40782144/. Date Accessed September 11, 2026.