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

A thin tube is passed through your nose or mouth to your stomach, then withdrawn back into your esophagus.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.

Your health care provider will ask you to fast (no eating and drinking) and avoid smoking after midnight before the test.

Some drugs may change the test results, and your health care provider may ask you to not take those for 24 hours before the test. These substances may include:

• Antacids
• Anticholinergics
• Cholinergics
• Adrenergic blockers
• Alcohol
• Corticosteroids
• H2 blockers
• Proton pump inhibitors

Do not stop any medication unless told to do so by your health care provider.

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

Esophageal pH monitoring is used to check how much stomach acid is entering the esophagus, and how well it is cleared. This test can also be performed during endoscopy by clipping a pH monitoring device to the lining of the esophagus. In infants, this test is usually used to evaluate the absence or presence of GERD and associated excessive crying or other problems.

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

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)
• Barrett's esophagus

• Esophagogastroduodenoscopy
• Barium swallow

No significant risks have been reported with this test, but the following may occur rarely:

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