Esophageal pH monitoring

Alternative names
pH monitoring - esophageal; Esophageal acidity test

Esophageal pH monitoring is a test that measures how often and for how long stomach acid enters the esophagus (the tube from the mouth to the stomach).

How the test is performed

A thin tube is passed through your nose or mouth to your stomach, then withdrawn back into your esophagus. The tube is attached to a monitor that measures the level of acidity in your esophagus.

You will wear this monitor on a strap and will be asked to keep a diary of your symptoms and activity over the next 24 hours. The next day you will return and the tube will be removed. The information from the monitor will be compared to the diary you provide.

Infants and children will most likely remain in the hospital for the esophageal pH monitoring.

How to prepare for the test

Your health care provider will ask you to fast and avoid smoking after midnight before the test.

Some drugs may alter the test results, and your health care provider may ask you to withhold those substances for 24 hours before the test. These substances may include:

  • Antacids  
  • Anticholinergics  
  • Cholinergics  
  • Adrenergic blockers  
  • Alcohol  
  • Corticosteroids  
  • H2 blockers

Do Not discontinue any medication unless advised to do so by your health care provider.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

  • Infant test or procedure preparation (birth to 1 year)  
  • Toddler test or procedure preparation (1 to 3 years)  
  • Preschooler test or procedure preparation (3 to 6 years)  
  • Schoolage test or procedure preparation (6 to 12 years)  
  • Adolescent test or procedure preparation (12 to 18 years)

How the test will feel

You may experience a brief gagging sensation as the catheter is passed through your throat.

Why the test is performed

Esophageal pH monitoring is used to assess how much stomach acid is entering the esophagus and how well it is cleared. In infants, this test is usually used to evaluate the absence or presence of GERD and associated excessive crying or other problems.

Normal Values

Normal values vary from person to person, and with different equipment and technique.

What abnormal results mean
An increased frequency or duration of acid in the esophagus often correlates with:

  • Heartburn  
  • Gastroesophageal reflux disease (GERD)  
  • Esophageal scarring  
  • Reflux esophagitis  
  • Dysphagia (a late symptom of esophageal scarring)

To determine the extent and severity of esophagitis, if present, further studies may be indicated:

  • Esophagogastroduodenoscopy  
  • Barium swallow

What the risks are
No significant risks have been reported with this test, but the following may occur very infrequently:

  • Arrhythmias during insertion of the tube (intubation)  
  • Breathing in of gastric contents if the catheter induces vomiting (see aspiration of vomitus)


Johns Hopkins patient information

Last revised: December 3, 2012
by Levon Ter-Markosyan, D.M.D.

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