24 hour pH Monitoring What is it? The 24-hour PH testing measures acid and non-acid reflux in the esophagus. Why is it done? Gastroesophageal Reflux Disease (GERD) occurs when contents in the stomach flow back into the esophagus. This happens when the valve between the stomach and the esophagus, known as the lower esophageal sphincter, does not close properly. This can be related to acid and non-acid reflux. GERD’s common symptoms are heartburn and/or acid regurgitation. Heartburn is a burning sensation felt behind the breast bone that occurs when stomach contents irritate the normal lining of the esophagus. Acid regurgitation is the sensation of stomach fluid coming up through the chest which may reach the mouth. Less common symptoms may include unexplained chest pain, wheezing, sore throat and cough, among others Esophageal pH monitoring and impedance plethysmography is a test used to evaluate for GERD and to determine the effectiveness of medications that prevent acid and non-acid reflux. This test measures the amount of acid and non-acid refluxing or backing up from the stomach into the esophagus (food pipe). Esophageal pH monitoring and impedance plethysymography is used in several situations to assess for gastroesophageal reflux disease (GERD). The first is to evaluate typical symptoms of GERD such as heartburn and regurgitation that do not respond to treatment with medications. In this situation, there may be a question whether the patient has GERD or whether antacid medications are adequate to suppress acid production. The second is when there are atypical symptoms of GERD such as chest pain, coughing, wheezing, hoarseness, sore throat. In this situation, it is not clear if the symptoms are due to gastroesophageal reflux. Occasionally, this test can be used to monitor the effectiveness of medications used to treat GERD. The test is often used as part of a pre-operative evaluation before anti-reflux surgery. What can I expect? The healthcare professional places a thin, flexible probe into the esophagus that will stay there for 24 hours while acid content is being measured. This information is transmitted to a small recorder that the patient wears on a belt.