Fiberoptic Endoscopic Examination of Swallowing (FEES)

How to Cite This Chapter: Gandhi P, Steele CM. Fiberoptic Endoscopic Examination of Swallowing (FEES). McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. Accessed April 16, 2024.
Last Updated: February 25, 2020
Last Reviewed: June 3, 2020
Chapter Information

Fiberoptic endoscopic evaluation of swallowing (FEES) is a validated procedure used to diagnose pharyngeal dysphagia and guide appropriate rehabilitation treatments. It involves passing an endoscope and camera transnasally into the upper pharynx to allow visualization of the pharynx and larynx during swallowing.


There are a number of clinical signs and symptoms of dysphagia that can be examined using FEES. Example include patients that present with hypernasality (excessive or inappropriate airflow into the nose during speech), laryngeal penetration or aspiration before the swallow is initiated, suspected nasal regurgitation, difficulty in swallowing during a meal due to fatigue, and those with abnormal vocal quality.

Additionally, there are numerous practical reasons why the FEES rather than the videofluoroscopic swallowing study (VFSS) may be the test of choice, given it can be performed at the bedside on short notice. This is particularly helpful for those patients who may have safety or mobility issues associated with VFSS because of radiation exposure, transportation to the radiology suite (mechanical ventilation and orthopedic traction, bedridden or wheelchair-bound individuals, pain due to fractures and contractures, quadriplegia), special positioning requirements, or morbid obesity.


Contraindications for FEES include cases of bilateral obstruction of nasal passages, refractory epistaxis, facial trauma, severe agitation, and inability to cooperate with the examination.


The overall risk is low. Complications include discomfort, epistaxis, mucosal injury or perforation, gagging, vomiting, aspiration, laryngospasm, allergic reaction or hypersensitivity to topical anesthesia or nasal sprays, and vasovagal response.


The patient can be positioned sitting upright in a procedure chair, wheelchair, or bed. After passing the endoscope transnasally and conducting an initial risk assessment, food and liquid are presented. Patients with dysphagia can self-feed during the assessment, mimicking natural delivery of food and liquid in a volume or at a rate that is typical for them. However, if the patient is unable to self-feed, an assistant may help present boluses to the patient via a cup, straw, or spoon. Providing food and liquid or varying the volumes and consistencies should trigger a swallow. No command is given to swallow unless necessary.

Foods that are dark, red or brown (meats), or translucent (water, juices) may be difficult to visualize, as they may blend in when viewed against the pharyngeal mucosa. Movement of the pharyngeal structures and passage of the bolus cannot be observed during the swallow due to the reflected light from the laryngeal and pharyngeal tissues into the endoscope, causing a brief condition referred to as “whiteout.”

The rationale for dyeing food blue using food coloring is based on acceptance, tradition, and assumptions rather than availability of evidence. Given that blue is not a color found in oropharyngeal secretions, blue dye has been used to detect aspiration for many years. The small volumes of blue dye used during FEES have not led to obvious adverse events.

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