Patients presenting to the Esophageal Center of Northwestern for evaluation of dysphagia between November, 2012 and April, 2016 that completed HRM and FLIP during upper endoscopy were prospectively included. Upper endoscopy was completed using sedation with midazolam (2 - 15 mg) and fentanyl (0 - 300 mcg); propofol (in addition to midazolam and fentanyl) was used with anesthesiologist assistance at the discretion of the performing endoscopist in some cases. Patients with previous upper gastrointestinal surgery, significant medical co-morbidities, eosinophilic esophagitis, severe reflux esophagitis (LA-classification C or D), or large hiatal hernia were excluded. Patients were often identified by referral for manometry, thus FLIP was commonly included with the endoscopic evaluation if an esophageal motility disorder was suspected. Enrollment of achalasia patients was prioritized, but limited to 70 patients: 49 of the achalasia patients were previously described.(11 (link)) We intentionally included an excess of achalasia patients to evaluate the diagnostic effectiveness of FLIP topography for this important esophageal motility disorder. Additional clinical evaluation (e.g. barium esophagram) were obtained and management decisions made at the discretion of the primary treating gastroenterologist. The study protocol was approved by the Northwestern University Institutional Review Board.