Flexible endoscopic evaluation of swallowing (FEES) is an instrumental assessment of swallowing function. A thin flexible endoscope is passed through the nose and into the throat allowing direct view of the throat, vocal folds, and airway. Food coloring is added to food and liquids to make them easier to identify during the evaluation. A speech-language pathologist (SLP) may recommend a FEES get more information about what may be contributing to any swallowing difficulty you may be experiencing and identify if food or liquid is being aspirated (going into the airway) instead of the esophagus.