<unk>  is the current gold standard for diagnosis of gastroesophageal reflux disease (GERD). It provides direct<unk> ysiologic measurement of acid in the esophagus and is the most objective method to document reflux disease, assess the severity of the disease and monitor the response of the disease to medical or surgical treatment. It can also be used in diagnosing laryngopharyngeal reflux.
Esophageal pH monitoring
Esophageal motility study
Impedance–pH monitoring
Gastric tonometry
Electrogastrogram
Sialoendoscopy
Nasoendoscopy
Transnasal esophagoscopy