Esophageal pH monitoring is a test that measures how often stomach acid enters the tube that leads from the mouth to the stomach (called the esophagus). The test also measures how long the acid stays there.

A thin tube is passed through your nose or mouth to your stomach. The tube is then pulled back into your esophagus. A monitor attached to the tube measures the acid level in your esophagus.

You will wear the monitor on a strap and record your symptoms and activity over the next 24 hours in a diary. You will return to the hospital the next day and the tube will be removed. The information from the monitor will be compared with your diary notes.

Infants and children may need to stay in the hospital for the esophageal pH monitoring.

This test can also be done during upper GI endoscopy by clipping a pH monitor to the lining of the esophagus.

Your health care provider will ask you to not eat or drink after midnight before the test. You should also avoid smoking.

Some medicines may change the test results. Your provider may ask you to not take these for between 24 hours and 2 weeks (or more) before the test. You also may be told to avoid alcohol.

Medicines that you may need to stop include:

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

DO NOT stop taking any medicine unless told to do so by your provider.

You briefly feel like gagging as the tube is passed through your throat.

Esophageal pH monitoring is used to check how much stomach acid is entering the esophagus. It also checks how well the acid is cleared downward into the stomach. It is a test for gastroesophageal reflux disease (GERD).

In infants, this test is also used to check for GERD and other problems related to excessive crying.

Normal value ranges may vary depending on the lab doing the test. Talk to your provider about the meaning of your specific test results.

Increased acid in the esophagus may be related to:

• Barrett esophagus
• Difficulty swallowing (dysphagia)
• Esophageal scarring
• Gastroesophageal reflux disease (GERD)
• Heartburn
• Reflux esophagitis

You may need to have the following tests if your provider suspects esophagitis:

• Barium swallow
• Esophagogastroduodenoscopy (also called upper GI endoscopy)

Rarely, the following may occur:

• Arrhythmias during insertion of the tube
• Breathing in of vomit if the catheter causes vomiting

pH monitoring - esophageal; Esophageal acidity test