This study is looking at a cohort of patients who have undergone treatment for Barrett's Esophagus (BE) and who have experienced complete eradication of the disease. The aim of the proposed study is to evaluate the histologic features of the neosquamous epithelium (NSE) following complete eradication of intestinal metaplasia (CE-IM) in patients undergoing routine surveillance biopsies and compare these data to a direct measure of reflux using 24hr pH impedance, to determine the correlation between histology and persistent reflux. These data will allow us to more accurately risk stratify patients for recurrence of BE following EET.

Inclusion Criteria:

• - Patients who have undergone endoscopic eradication therapy and 24hr pH impedance testing as part of standard of care between 2009 and 2014.
• - Individuals who have signed a consent to be part of the Prospective Evaluation of Barrett's Esophagus Study population.

Exclusion Criteria:

• - Individuals who are not yet adults (infants, children and teenagers), pregnant women and prisoners will be excluded from the study.
• - Patient who were previously unable or unwilling to give consent to the Prospective Evaluation of Barrett's Esophagus Study will be excluded.

Patients who have undergone EET and 24hr pH impedance testing as part of standard of care at Northwestern Memorial Hospital between 1/1/2009 and 12/31/2014 and who have enrolled in the Prospective Evaluation of Barrett's Esophagus database (NCT02634645).