Oesophageal pH monitoring
This is also known as 24-hour oesophageal pH monitoring. The test uses a small probe to measure the acidity of your oesophagus (gullet). Doctors measure acidity or alkalinity as ‘pH’.
Why is the test required?
People with gastro-oesophageal reflux, commonly known as heartburn, have abnormal backflow of the acidic stomach juices into the lower oesophagus. This acidity causes the burning sensation of heartburn.
Gastro-oesophageal reflux can usually be diagnosed using tests such as endoscopy, where a lighted, flexible tube is passed down your throat to look at the lining of the oesophagus. Sometimes, however, a doctor wants to get a clearer idea of what is happening in your oesophagus and how that relates to your symptoms of reflux. Then, they may recommend that you have 24-hour oesophageal pH testing.
How is the test carried out?
A fine tube (called a catheter) is threaded through your nose down into the oesophagus to insert the pH probe, which measures the acidity there. This tube is usually left in place for 24 hours while you are at home.
A small box, carried on your belt, makes recordings of the pH (level of acidity) of your oesophagus. You may also be asked to keep a diary to record your symptoms during the test.
A new procedure, called ‘catheterless oesophageal pH monitoring’, may be a more comfortable alternative test. In this procedure, there is no tube left in place. Instead, a small plastic capsule is attached to the wall of the oesophagus during an endoscopy. The capsule contains a pH sensor that continuously monitors the acidity of the oesophagus and transmits the data to a small receiver worn around the waist. The capsule spontaneously comes away from the wall of the oesophagus after a few days, and passes out of the body in the faeces.
What will the test show?
The recording will show the level of acidity of your oesophagus through the day, during meals and also while you are asleep at night. This will help the doctor to see whether it is linked to your symptoms of reflux.
This test is usually undertaken only if there is an uncertainty about a diagnosis, even after an endoscopy and/or a trial of medication.
Last Reviewed: 26 January 2010
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