Esophageal pH monitoring
Esophageal pH monitoring is a test that measures how often and for how long stomach acid enters the tube that leads from the mouth to the stomach (esophagus).
pH monitoring - esophageal; Esophageal acidity test
How the test is performed
A thin tube is passed through your nose or mouth to your stomach. Then it is pulled 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 to the hospital and the tube will be removed. The information from the monitor will be compared with the diary notes you provide.
Infants and children may need to stay in the hospital for the esophageal pH monitoring.
How to prepare for the test
Your health care provider will ask you to not eat or drink (fast) and avoid smoking after midnight before the test.
Some drugs may change the test results. Your health care provider may ask you to not take those drugs for 24 hours to 2 weeks (or more) before the test, depending on the medication. These substances may include:
- Adrenergic blockers
- H2 blockers
- Proton pump inhibitors
Do not stop taking any medication unless told to do so by your health care provider.
How the test will feel
You may experience a brief gagging sensation as the tube is passed through your throat.
Why the test is performed
Esophageal pH monitoring is used to check how much stomach acid is entering the esophagus, and how well it is cleared downward into the stomach. It is a test for gastroesophageal reflux disease (GERD).
This test can also be performed during upper GI endoscopy by clipping a pH monitoring device to the lining of the esophagus. In infants, this test is also used to check for GERD and related excessive crying or other problems.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
Increased acid in the esophagus may be a sign of, or occur with:
- Barrett's esophagus
- Difficulty swallowing (dysphagia)
- Esophageal scarring
- Gastroesophageal reflux disease (GERD)
- Reflux esophagitis
If you are suspected to have esophagitis, you may need these additional tests:
What the risks are
No significant risks have been reported with this test, but the following may occur rarely:
Richter JE, Friedenberg FK. Gastroesophageal reflux disease. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier;2010:chap 43.
Orlando RC. Diseases of the esophagus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 140.
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.