Health Information and Tools > Patient Care Handouts >  Esophageal pH: About This Test

Main Content

Esophageal pH: About This Test

The esophagus and stomach

What is it?

Your esophagus is the tube that connects your throat to your stomach. It moves food and liquid down to the stomach. Stomach acid can come up into your esophagus. This can cause symptoms such as heartburn.

This test checks the acid content (pH) in your esophagus. A low pH for long periods may mean that you often have backflow (reflux) of stomach acid into the esophagus. This is called gastroesophageal reflux disease, or GERD.

Why is this test done?

An esophageal pH test is done to:

  • Help find the cause of GERD symptoms if you haven't been helped by medicine and your esophagus looks normal during an endoscopy test.
  • Check problems that may be related to reflux, such as asthma, cough, or chest pain.

How do you prepare for the test?

To prepare for this test:

  • Do not take antacids for 24 hours before the test.
  • Stop taking heartburn medicines if your doctor tells you to.
  • Follow your doctor's instructions for using other medicines before the test.
  • Do not drink alcohol or smoke for 24 hours before the test.
  • Follow your doctor's instructions for when to stop eating and drinking before the test.

How is the test done?

  • You will be seated. You may be given a spray medicine that numbs your nose and throat.
  • A probe that measures pH will be passed through a tube in your nose and into your lower esophagus. This may make you feel like you have to gag. To help overcome this feeling, focus on breathing slowly. The tube is taped near your nose. The probe tells your doctor if the pH drops because of liquid from your stomach backing up into your esophagus.
  • For longer pH monitoring, the pH probe is attached to a small recorder. You carry the device by a strap around your waist or over your shoulder. The probe checks the pH of your esophagus for up to 24 hours while you go about your daily routines. You will need to use a diary to keep track of your activities and symptoms. You may be asked to avoid high-acid foods. You will not be able to take a bath, except for a careful sponge bath, or do anything else that might get the device wet.
  • For wireless pH monitoring, you will have an endoscopy procedure. A capsule with a pH-sensitive transmitter in it is attached to the lining of your esophagus. You carry a small receiver in your pocket or wear it around your waist for 2 to 4 days. You will need to use a diary to keep track of your activities. You'll also track what you eat and drink and any symptoms you have. You will press the symptom button when you have heartburn, chest pain, or regurgitation. You can bathe during the testing period. When the testing period is over, you will return the receiver and diary to your doctor. The capsule will pass out of your body in a bowel movement, usually within a few days.

How long does it take?

An esophageal pH test in your doctor's office can take up to an hour. Longer pH monitoring may last up to 4 days.

What happens after the test?

After the test is over, your nose and throat may feel sore. But this should get better within a day or so.

The capsule attached to the esophagus in a wireless pH test will fall off after a few days and pass in the stool.

You can usually get your results within a few days.

Many conditions can affect the results of this test. Your doctor will discuss your results with you.

Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if you are having problems. Ask your doctor when you can expect to have your test results.

Where can you learn more?

Go to

Enter E110 in the search box to learn more about "Esophageal pH: About This Test".

Care instructions adapted under license by your healthcare professional. If you have questions about a medical condition or this instruction, always ask your healthcare professional. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.