Dysphagia Knowledge Hub — 吞嚥困難知識庫
FEES: Fibreoptic Endoscopic Evaluation of Swallowing — A Patient Guide
If you or someone you care for has been referred for a FEES assessment, it is natural to feel uncertain about what to expect. This guide explains the procedure in plain language — what the speech-language therapist (SLT) is looking for, what you will experience, how FEES compares to the more widely known videofluoroscopic swallowing study (VFSS), and what happens after the assessment.
What Is FEES?
FEES stands for fibreoptic endoscopic evaluation of swallowing. It is an instrumental swallowing assessment that uses a flexible endoscope — a very thin, soft tube with a tiny camera and light at its tip — passed gently through one nostril and positioned above the throat, giving a direct view of the larynx (voice box) and pharynx (throat) during swallowing.
Unlike VFSS, which uses X-ray imaging, FEES provides a direct colour video image of the structures involved in swallowing. It has no radiation exposure, can be performed at the bedside or in an outpatient clinic without specialised radiology equipment, and can be repeated as often as clinically necessary.
FEES was developed by Susan Langmore and colleagues in the 1980s and is now considered one of the two gold-standard investigations for pharyngeal dysphagia, alongside VFSS.
How FEES Differs from VFSS
| Feature | FEES | VFSS |
|---|---|---|
| Imaging type | Direct endoscopic camera | X-ray fluoroscopy with barium contrast |
| Radiation | None | Low-dose X-ray (equivalent to chest X-ray) |
| Location | Bedside, clinic, ward, community | Radiology suite only |
| Oral phase visibility | Not directly visible | Fully visible |
| Pharyngeal phase | Excellent direct view | Excellent lateral view |
| Secretion assessment | Excellent | Limited |
| White-out during swallow | Yes (brief moment of no image) | No (continuous image throughout) |
| Portability | High — can go to patient | Low — patient must attend radiology |
| Food colouring needed | Yes (to identify aspirated material) | No (barium provides contrast) |
| Cost (HK private) | HK$2,500–5,000 | HK$3,000–6,000 |
The two tests are complementary rather than competitive. FEES excels at assessing secretion management and laryngeal sensation; VFSS provides better visualisation of the oral phase and upper oesophageal sphincter. When resources allow, both may be used.
What You Will Experience During the Procedure
Before the scope is passed: The SLT will explain the procedure and obtain your consent. A topical anaesthetic spray (usually lignocaine) may be applied to one nostril to reduce discomfort; this is standard in some centres and optional in others. You will be seated upright, which is the optimal position for swallowing assessment.
Passing the endoscope: The flexible scope is approximately 3–4 mm in diameter — narrower than a pencil. It is passed through the more patent nostril and advanced gently to the level of the epiglottis. Most people describe a sensation of mild pressure or the urge to sneeze as it passes the nasal turbinates; this typically settles within a few seconds. The scope does not enter the throat in a way that causes gagging, as it is positioned above the level that triggers the gag reflex in most people.
During the assessment: The SLT will ask you to perform various tasks — humming, phonating, breath-holding — before offering food and drink. Coloured dye (usually blue or green food colouring) is added to the food and liquid so that any aspirated material can be identified against the pale tissues of the larynx and trachea.
You will swallow a series of boluses of increasing size and varying consistency — thin liquid, thickened liquid, purée, and soft food. The SLT watches the endoscope image on a monitor and may try compensatory strategies (head turn, effortful swallow) mid-assessment to see whether they reduce any observed problems.
After the scope is removed: The scope is withdrawn gently. The procedure typically lasts 15–25 minutes. There is no recovery time required; you can resume normal activities immediately (though if topical anaesthetic was used, you should wait 30–60 minutes before eating or drinking, to allow sensation to return).
What FEES Reveals
Secretion management: One of FEES’s most distinctive advantages. Before any food or drink is introduced, the SLT assesses whether your secretions — saliva and mucus — are pooling in the pharynx, penetrating the laryngeal vestibule, or reaching the trachea. Secretion aspiration during sleep or between swallows is a major source of aspiration pneumonia in patients with severe neurological dysphagia. FEES is the only instrumental tool that allows direct, real-time observation of this.
White-out: For a brief moment during the swallow itself, the image is obscured by the movement of pharyngeal structures around the scope tip — this is called white-out. It means FEES cannot observe the exact moment of maximal pharyngeal contraction or bolus transit through the cricopharyngeus. This is the main limitation compared to VFSS, where X-ray imaging continues throughout the swallow.
Residue patterns: After the white-out clears, the SLT can see any food or liquid that has pooled in the valleculae or pyriform sinuses — structures where residue commonly accumulates when pharyngeal clearance is reduced. The location, quantity, and consistency of residue inform the rehabilitation plan.
Laryngeal penetration and aspiration: Whether dyed food or liquid enters the laryngeal vestibule (penetration) or passes below the vocal cords into the trachea (aspiration) is clearly visible in the post-swallow view. If aspiration is observed, the SLT notes whether a cough response is triggered (overt aspiration) or absent (silent aspiration).
Laryngeal sensation: Some FEES protocols include a laryngeal sensory test — a small puff of air delivered through the scope to test whether the aryepiglottic folds respond reflexively. Reduced laryngeal sensation is associated with silent aspiration and can be directly assessed with FEES but not with VFSS.
Vocal cord movement: FEES provides a direct view of the vocal cords, allowing assessment of vocal cord paralysis or paresis, which can both cause and complicate dysphagia.
When Is FEES Preferred over VFSS?
At the bedside or in community settings: FEES equipment is portable. For patients who are acutely unwell, bedbound, or cannot be transported to a radiology suite, FEES may be the only feasible instrumental assessment.
When radiation is a concern: Pregnancy, or when repeated studies are needed over a short period, may make FEES preferable.
When secretion management is the primary question: In patients with tracheostomies, severe neurological dysphagia, or recurrent aspiration pneumonia where the mechanism is thought to be secretion aspiration rather than food/fluid aspiration, FEES provides superior information.
When barium cannot be used: Rare situations where the patient has a known barium allergy or contraindication to barium swallow.
Cost and access: In the Hong Kong private sector, FEES may be more accessible in some ENT or SLT clinic settings than fluoroscopy suites with an SLT service.
How Results Guide Management
As with VFSS, FEES findings directly inform the IDDSI diet level recommendation. The SLT will identify which consistencies are safe, whether compensatory strategies are effective, and whether the current management plan should be modified.
FEES is also used to monitor response to therapy. Patients undertaking swallowing exercises (tongue base retraction exercises, Mendelsohn manoeuvre, effortful swallow) may have repeat FEES to document structural improvement before diet advancement.
For patients with tracheostomies, FEES with a Passy Muir valve (a one-way speaking valve) is a standard assessment protocol, allowing evaluation of swallowing with airflow restored to the upper airway.
Availability in Hong Kong
Public (HA) hospitals: FEES is offered at ENT and SLT departments in several HA hospitals, including Queen Elizabeth Hospital, Queen Mary Hospital, Prince of Wales Hospital, and Tuen Mun Hospital. Inpatient referrals are typically processed within days; outpatient waiting times are longer.
Private sector: A number of ENT specialists and SLT practices in Hong Kong offer FEES as part of a clinic assessment. It is most commonly available at private hospitals (Matilda International, Canossa, Hong Kong Adventist) and specialist clinics in Kowloon and Hong Kong Island. Some community-visiting SLT services offer FEES in care home or home settings.
Questions to Ask Before Your FEES Assessment
- Will topical anaesthetic be used, and what should I expect in terms of discomfort?
- Will a speech-language therapist and a physician both be present?
- Can I see the video recording afterwards, and will it be explained to me?
- How long will I wait for a written report and revised diet recommendations?
- Are there situations in which you would stop the procedure early?
FEES is a well-tolerated, safe, and highly informative investigation. Understanding what to expect helps you engage with the process confidently and ensures the clinical team can obtain the information they need to support your swallowing management.