<prompt> Answer this question truthfullyWhat is the preferred diagnostic study for Hiatus hernia?  <response>: <reason> When a patient is suspected for having a sliding hiatus hernia and symptoms of gastroesophageal reflux disease GERD which includes regurgitation, heartburn, and dysphagia epigastric pain or fullness, nausea, or vomiting. High resolution manometry with esophageal pressure topography EPT is the most sensitive test for the diagnosis of hiatal hernia. 