24 hr pH/impedance monitoring is a catheter-based test using a combination of pH and impedance sensors for the identification of reflux at multiple locations, including the esophagus and pharynx. Data collected differentiates acid and non-acid reflux in patients with an array of symptoms.

With these measurements, doctors can evaluate the number of reflux events, the acid content of each event and how long each event lasted. This helpful information can also help doctors diagnose gastroesophageal reflux disease (GERD) and other disorders. This test may also determine if the cause of the symptoms may be extraesophageal in nature.