A pH/impedance probe is a diagnostic technique used to determine the severity of gastroesophageal reflux disease in children and adults. This test is conducted using a special type of catheter known as an esophageal probe to determine if the reflux content is acidic. The pH level is assessed to determine acid concentration, and the amount of both acid and nonacid reflux are measured. Performed as an outpatient procedure, a pH/impedance probe may begin with an esophageal motility test that determines proper placement of the probe. This involves inserting a small catheter into a nostril and guiding it into the esophagus.
The catheter is then slowly removed and the pH/impedance probe is inserted in its place. The probe, which is connected to a small recording device, will remain in the esophagus for 24 hours. The next day, the probe is removed and the results of the test can be assessed. This procedure is considered safe, but some patients experience minor throat irritation or discomfort while the probe is in place.