What is Functional Endoscopic Sinus Surgery?

Functional Endoscopic Sinus Surgery (FESS)

Anatomy / Physiology

TThe anatomy of the sinuses has not changed for many years, but our understanding of the physiology of the nose and sinuses has evolved significantly in more recent years. Our concept of how sinuses naturally drain has been the source from which we have adapted our surgical techniques in order to improve these natural drainage patterns.

There are a number of sinuses.

  • Maxillary sinus x2
  • Anterior ethmoid sinus x2
  • Posterior ethmoid sinus x2
  • Frontal sinus x2 (variable in size and development)
  • Sphenoid sinus x1 (often split into 2 by a bony septa)

The maxillary sinus (located under your cheek) drains into a narrow area between two bony folds in the lateral wall of the nose, called the middle meatus (area between the middle and inferior turbinates). In addition the anterior ethmoids and the frontal sinus drains here too. This is a crucial area of confluence referred to as the osteomeatal complex and is where a lot of problems exist with respect to sinusitis. Surgery is often focused here to improve the drainage.


The surgery is referred to as Functional as you are not just anatomically looking at creating a solution but you are improving on the normal function / physiology of the sinus drainage pathway.

The surgery is referred to as Endoscopic as the surgeon uses fine telescopes intranasally to give an excellent visualization of the nose. With the use of fine instruments too the surgeon can rectify any anatomical or pathological anomalies in order to improve the natural drainage of the sinuses.

The surgeon almost always uses a CT scan as a map through the nose and sinus and this will have been performed preoperatively to help with the diagnostic workup of the patient.

Functional Endoscopic Sinus Surgery

Preoperative CT Scan showing opacification of the left maxillary and ethmoid sunuses.

Access sometimes has to be improved with an additional procedure of a Septoplasty to allow visualization of areas obstructed by a deflected nasal septum.

This surgery can often be performed as a day case but occasionally warrants an overnight stay. The nose may be dressed with small soft intranasal packs that are removed after a set length of time depending on the surgeon.

It is not uncommon to feel blocked in the nose for approximately a week as the swelling intranasally goes down and regular nasal douching with appropriate products as recommended by your surgeon should be used to flush out any crusts or blood from the nose. It strongly advised not to blow your nose in the postoperative period.