The term pH refers to acidity or alkalinity. In this case, what's most important is the acidity level of your esophagus. The number most doctors think is good for GERD is an acidity level of 4 or more in the esophagus.
But you can't measure esophageal acidity from the outside- the doctor has to go in to get that measurement, using a special pH monitoring device. This is not information your doctor can obtain from an endoscopy. As a result, this test may be done if your symptoms indicate GERD but your endoscopy results were negative.
This test is also often used if the patient has atypical or unusual symptoms of GERD, such as asthma, unexplained chest pains, or other symptoms that are often characteristic of or linked to GERD. In such cases, the doctor is suspicious but may not want to treat for GERD when there is no proof that it exists. The pH test will provide the proof, if the disease is present.
The ambulatory pH procedure involves spraying the nostrils with numbing medication and then inserting a fine catheter through the nose, down the throat, and into the esophagus. It stays there for twenty-four hours while the equipment collects information. The procedure is very comfortable and painless. Except for a slight gagging when the catheter is inserted, there is no problem. Patients can go about their normal routine and can even go to work afterwards, if they wish. However, many patients decide against going to work because of the embarrassment of the rather unsightly catheter in their nose.
The reason the test is done over twenty-four hours rather than simply at one time is that you can't get an idea of a true pattern unless data are recorded for a twenty-four-hour period. In addition, some degree of acid reflux is considered normal. Only when the reflux exceeds normal parameters or causes problems is it considered GERD.
Connected to the probe is a data recorder, which you can carry in your pocket, that will provide information to the doctor; it's sort of your won little flight recorder black box of information. The recorder will determine incidences and durations of reflux while ou drink and eat and go about your daily life as best you can with this contraption inside you. individuals may even smoke if they wish, althought smoking will undoubetedly cause the probe to reflect a worsening of reflux symptoms.
As to any disadvantage, the ambulatory pH test may not be available where you live. Also, some patients find it inconvenient and cumbersome.