Fibreoptic Endoscopic Evaluation of Swallowing — universally abbreviated FEES — is an instrumental swallowing assessment performed by passing a thin flexible camera through the nose to visualise the throat during swallowing. It is one of two gold-standard instrumental methods for evaluating dysphagia, alongside videofluoroscopic swallow study (VFSS). Understanding what FEES involves helps patients and families make informed decisions and reduces anxiety before the procedure.
FEES was first described by Langmore and colleagues in 1988 and has since become a standard clinical tool in dysphagia practice worldwide. The procedure uses a flexible nasendoscope — a fibreoptic tube approximately 3 mm in diameter — inserted through one nostril to rest just above the larynx (voice box). From this position, the camera provides a direct overhead view of the pharynx, larynx, vocal folds, and epiglottis during swallowing.
The endoscope is connected to a camera head and a light source. Images are displayed on a monitor and recorded for review. The examining clinician — typically a speech-language therapist, otolaryngologist, or specially trained physician — watches the recorded footage in real time and reviews it frame by frame afterwards to analyse the mechanics of each swallow.
Both FEES and VFSS assess the pharyngeal phase of swallowing, but they work through fundamentally different mechanisms and each has distinct advantages.
VFSS uses X-ray fluoroscopy with barium-contrasted food and liquid. It visualises the entire swallow from lips to oesophagus in moving image format, including the oral phase, and can image the oesophagus if required. However, it requires a radiology department, involves radiation exposure, and the patient must be mobile enough to sit or stand at the fluoroscopy unit.
FEES uses direct optical visualisation without radiation. Key advantages over VFSS include:
The primary limitation of FEES is the “white-out” phenomenon: the camera view is briefly obscured at the moment of laryngeal closure during the swallow, so the exact instant of aspiration cannot always be captured. VFSS does not have this limitation.
During FEES, the examiner observes:
The Penetration-Aspiration Scale (PAS), an 8-point ordinal scale, is commonly used to quantify the severity of airway invasion observed on FEES.
The procedure takes approximately 15 to 30 minutes including setup. Most patients tolerate it with mild discomfort rather than significant pain.
Before the scope is passed: the examiner will inspect one or both nostrils to determine which is more patent. A small amount of local anaesthetic spray or gel may be applied to the nostril lining to reduce discomfort; the choice depends on the clinician’s protocol and the patient’s medical situation. (Note: if sensory testing is a key aim of the assessment, topical anaesthetic to the larynx is avoided as it would confound the sensory findings.)
During insertion: the scope passes along the floor of the nasal cavity. Patients typically feel pressure and may have watery eyes — these are normal reflexes. Gagging is uncommon because the scope stops above the larynx rather than entering the oropharynx like a standard oropharyngoscope.
During swallowing trials: the examiner offers food and liquid in small measured amounts, starting with the texture most likely to be safe. The patient swallows normally while the camera records. The examiner may ask the patient to try strategies such as head turns or multiple swallows.
After the scope is removed: there is no recovery period. The slight nasal discomfort resolves quickly. The local anaesthetic, if used, wears off within 30 minutes.
FEES is the preferred assessment when:
In Hong Kong’s public hospital system, FEES is performed in selected speech therapy and otolaryngology departments within the Hospital Authority (HA). Prince of Wales Hospital (PWH), Queen Mary Hospital (QMH), and Tuen Mun Hospital have established FEES services. Availability varies by hospital and waitlist; urgent inpatient referrals typically take priority over outpatient appointments.
In the private sector, several ENT clinics and hospitals in Kowloon and Hong Kong Island offer FEES. Fees range approximately HK$3,000 to HK$6,000 for a combined clinical and instrumental assessment.
When booking, confirm that the service includes a trained speech-language therapist co-assessing alongside the endoscopist — a shared clinical and instrumental assessment yields richer diagnostic information than endoscopy performed by a physician alone without SLT co-evaluation.