What Happens During FESS Surgery for Chronic Sinusitis?

Functional Endoscopic Sinus Surgery (FESS) is a procedure designed to clear blockages, improve drainage, and increase access for medical treatments in your sinuses. During the surgery, the ear, nose, and throat (ENT) surgeon uses a thin camera (endoscope) and specialized, tiny instruments to reach the ethmoid sinuses—a group of small, air-filled spaces located between your eyes and the bridge of your nose.

Instead of removing all the structures, the surgeon removes selected thin, honeycomb-like bony partitions separating these small air cells ^[1][2]. The goal is to widen the natural drainage pathways so that trapped mucus can escape and topical medicated rinses can reach the deeply inflamed tissue ^[3][4].

The Surgical Process

The ethmoid sinuses are structurally similar to a honeycomb, made up of many delicate bony partitions covered in a mucous membrane lining. Chronic ethmoidal sinusitis is primarily a persistent inflammatory condition. This inflammation causes the lining to become severely swollen, impairing mucus clearance. In some people, non-cancerous growths called polyps may form, further blocking the area.

During FESS, the surgeon performs the procedure entirely through your nostrils, without making any external cuts on your face.

• Removing blockages: The surgeon carefully cuts away diseased tissue, polyps (if present), and selected thin bony walls of the ethmoid air cells ^[1].
• Widening pathways: By taking down these internal partitions, the surgeon creates a wider corridor. They may also enlarge the natural openings (ostia) that connect your other sinuses to the nasal passage ^[5].
• Preserving healthy tissue: The surgery is “functional,” meaning it aims to restore function. The surgeon removes diseased tissue and obstructing bone while sparing as much of your normal, healthy sinus lining (mucosa) as possible ^[6][7].

Every surgery is individually tailored based on your symptoms, endoscopy, and imaging. Before the procedure, the surgeon uses a CT scan as a map of your specific anatomy to identify disease and navigate around critical nearby structures, such as the eyes (orbit), the base of the skull, and major blood vessels ^[6][8].

Why Altering Your Anatomy Helps

Creating wider pathways serves two vital purposes for treating chronic sinusitis:

Improving Airflow and Drainage

By removing selected blockages, FESS alters the physical anatomy of your nasal passages. This wider space improves airflow into the sinuses and helps mucus drain, rather than remaining trapped ^[9][10]. While this structural change is long-lasting, it does not guarantee a permanent cure; swelling, scarring (synechiae), or returning polyps can sometimes narrow the openings again, requiring ongoing medical management or, rarely, revision surgery ^[11][12].

Allowing Rinses to Reach the Inflammation

Surgery is rarely a standalone cure for chronic sinusitis; it is a vital step that makes ongoing medical treatment more effective. Before surgery, swollen tissue and narrow pathways block nasal sprays and rinses from getting deep into the sinuses.

After FESS, the enlarged openings allow large-volume saline and, if prescribed, medicated rinses (like topical steroids) to enter the sinus spaces ^[3][13]. Studies show that larger surgical openings improve how well these medications can coat the inflamed tissue, aiding healing and symptom relief ^[14][15].

Important Note on Sinus Rinses: If your surgeon instructs you to use sinus rinses, always use sterile, distilled, or previously boiled and cooled water to prevent serious infections. The specific medication, dose, and frequency of your rinses will be determined by your surgeon based on your individual needs.

What to Expect: Risks and Recovery

While FESS is a common and generally safe procedure, it involves operating near delicate structures.

• Recovery: In the days following surgery, you can expect some bleeding, nasal congestion, and crusting as the area heals. Your surgeon may schedule follow-up visits to clean (debride) the healing sinuses and ensure the pathways remain open ^[4].
• Risks: Because the ethmoid sinuses border the eyes and the brain, there are rare but serious risks. These include injury to the eye or vision changes, major bleeding, and cerebrospinal fluid (CSF) leaks (fluid surrounding the brain leaking into the nose) ^[16][17]. Your surgeon will discuss these specific risks with you during the consent process.