This study will evaluate the role the balloon mucosal impedance may have in diagnosing and monitoring the patients with Eosinophilic Esophagitis. We will compare the results of the balloon mucosal impedance in patients with Eosinophilic esophagitis and controls.

The standard diagnostic evaluation for EoE includes upper endoscopy with esophageal biopsies. Recently we completed the study "Mucosal impedance in eosinophilic esophagitis and the effect of treatment" using a new technology allowing for direct assessment of mucosal impedance at the time of routine upper endoscopy to assess esophageal integrity and disease activity and alevate the need for biopsies.

For this study, Sandhill Scientific has customized a Mucosal Impedance balloon (MI) assembly to provide precise measurements over a broad area of esophageal epithelium, while eliminating the fluids and spanning across a 10 mm luminal area using the same direct assessment as the mucosal impedance at the time of routine upper endoscopy.

Inclusion criteria:

• Adults ages 18-90 undergoing clinically indicated upper endoscopy
• Patients with EoE, defined as dysphagia with histologic finding of greater than or equal to 15 eosinophils per high powered field on esophageal biopsy despite at least 6 weeks of twice daily proton pump inhibitor therapy
• Patients undergoing clinically indicated upper endoscopy for indications other than dysphagia or GERD with normal appearing esophageal mucosa.

Exclusion criteria:

• Medical conditions such as severe heart or lung disease that preclude safe performance of endoscopy
• Patients with conditions known to be associated with esophageal eosinophilia, including Crohn's disease, Churg-Strauss, achalasia, and hypereosinophilic syndrome
• Inability to read due to: Blindness, cognitive dysfunction, or English language illiteracy

Patients with Eosinophilic Esophagitis having an upper endoscopy. Patients having an upper endoscopy for dysphagia or GERD