Functional Endoscopic Sinus Surgery (FESS)

What is FESS?

FESS is a minimally invasive procedure that is used to visualise, diagnose and treat sinus problems. Unlike conventional sinus surgery, it does not require an external incision.

As FESS is a type of nasal endoscopy, it involves the insertion of an endoscope and specialised surgical instruments into the nostrils. These tools help your doctor to:

  • Access and visualise the inside of your nose and sinuses, using a camera system attached to the endoscope.
  • Use specialised tools to remove blockages in the sinuses. Blockages may occur due to inflammation and swelling in the sinuses. Left untreated, blockages can block the flow of mucus and cause sinusitis, leading to pain, drainage and impaired breathing.

Why do you need FESS?

FESS is used to treat:

  • Severe acute sinusitis
  • Recurrent acute sinusitis
  • Chronic sinusitis
  • Nasal polyposis

FESS surgical techniques can also be used to remove tumours involving the nose and sinuses.

What are the risks and complications of FESS?

As with any surgery, FESS carries some risks, such as:


During surgery, small amounts of blood loss are common. If there is excessive bleeding, your surgery may be stopped. However, this occurs very rarely.

After surgery, mild bleeding is common in the first 24 hours. Most patients can tolerate mild bleeding during and after surgery. To control bleeding after your surgery, your surgeon may insert temporary nasal packing in your nose.


Although FESS helps to reduce the infection load in the sinuses, there is still a small risk of infection. To treat, control or reduce the risk of infection, antibiotics are usually given during and after surgery.

Vision changes

During FESS, surgery is performed very close to or at the bone that separates the sinuses from the eye. While extremely rare, unintentional injury to the eye or bleeding around the eye may lead to double vision or vision loss. These changes may be temporary or permanent.

Another rare complication is an injury to the tube that drains tears from the eyelids to the nose. This complication can result in excessive tearing. However, it can be corrected through surgery on the tear sac.

Cerebrospinal fluid (CSF) leak

During FESS, surgery is performed very close to or at the bone that separates the nose or sinus from the brain. While very rare, a CSF leak may occur due to unintentional movements of the bone. Surgery is usually required to repair a CSF leak. However, this can almost always be performed endoscopically through the nostrils.

Why choose Mount Elizabeth Hospitals?

At Mount Elizabeth Hospitals in Singapore, we are committed to giving you comprehensive care. Our multidisciplinary team of ENT surgeons, nurses and therapists are here to guide you through your treatment options for sinusitis and help you breathe more comfortably.

Using our hospitals' modern equipment and facilities, our specialists perform minimally invasive techniques and computer-aided robotic surgery during FESS to reduce trauma and scarring while improving success rates and recovery speed.

Our otolaryngologists (ENT specialists)

At Mount Elizabeth Hospitals, our team of ENT specialists are experienced in treating sinusitis and performing endoscopic surgery to clear persistent blockages in the sinuses.

They are supported by a team of multidisciplinary healthcare professionals who will guide you every step of the way to ensure that you will have a comfortable and personalised experience.

This page has been reviewed by our medical content reviewers.

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