In gastroenterology, esophageal pH monitoring is the current gold standard for diagnosis of gastroesophageal reflux disease (GERD).

[citation needed] Although there remains no gold standard for the diagnosis of GERD, ambulatory esophageal pH monitoring can provide data to guide further evaluation and treatment of patients with GERD-associated symptoms.

Because this method is associated with nasal and pharyngeal discomfort and rhinorrhea, patients may have limited their activity and become more sedentary during the monitored period.

Esophageal pH monitoring is performed for 24 or 48 hours and at the end of recording, a patient's tracing is analyzed and the results are expressed using six standard components.

[7] The widespread prescription of proton pump inhibitors (PPI) by primary care physicians has resulted in a change in pattern of GERD in patients who use these medications.

In 1991 Silny was the first investigator who described Multichannel Intraluminal Impedance (MII), a technique which detects intraesophageal bolus transport.

[citation needed] Retrograde flow of gastric contents to the upper aerodigestive tract causes a variety of symptoms such as cough, asthma and hoarseness.

In an effort to improve diagnostic accuracy of testing, a catheter with two pH sensors has been used to measure the degree of esophageal acid exposure in both distal and proximal esophagus.