What is the definition or description of: esophageal ph test?

Esophageal pH test: Esophageal ph testing is a diagnostic modality to assess the contents of the esophagus. This can be accomplished by implanted device or insertion of an impedance probe into the esophagus. Over a defined time period, the acidity of esophageal contents are assessed and correlated with the patient's recorded concomitant symptoms.