The most common method to distinguish EoE from reflux disease is to perform an upper endoscopy (also known as esophagoduodenoscopy (EGD) or upper GI)  looking for increased numbers of eosinophil white blood cells in esophageal biopsies. Appropriate medications and dosing should be discussed with the gastroenterologist who is performing the endoscopy.  You should discuss whether these endoscopies should be performed with any acid blocking medications.  However, there is a new subtype of EoE identified which can be healed with use of PPI class of medications eg omeprazole, lansoprazole, esomeprazole, etc.  So a normal endoscopy while taking these medications may indicate this PPI-Responsive EoE.

It is advisable to have 3 or more esophageal biopsies taken during the procedure since EoE can sporadically involve the esophagus so the diagnosis may be missed if only 1 or 2 biopsies are taken. Even if the appearance of the esophagus looks normal to the eye, biopsies should be still considered since significant eosinophilic inflammation can be seen in these areas.

In addition, the esophagus may have some visual changes that can support the diagnosis of EoE. Often, a pale color or pallor to the esophageal tissue is present. Another common findings are white specks or flecks noted on the esophageal mucosa which represent eosinophilic microabscesses. In additional creases or furrowing along the length of the esophagus can be seen. A less common finding is circumferential creasing can occur described as a feline esophagus or trachealization (referring to the resemblance of the trachea). Extensive narrowing, that is esophageal strictures, can also be observed usually from longstanding inflammation which results in the difficulty swallowing that is often seen in EoE. Finally, as mentioned above the esophagus can look normal in a patient with eosinophilic esophagitis. And conversely, reflux disease can result in similar appearances, so the biopsies become central in confirming or ruling out the diagnosis of EoE.