Esophageal pH monitoring
pH monitoring - esophageal; Esophageal acidity test
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.
How the Test is Performed
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 (pH) 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.
A newer method of monitoring esophageal acid (pH monitoring) is by use of a wireless pH probe.
- This capsule-like device is attached to the lining of the upper esophagus with an endoscope.
- It remains in the esophagus where it measures acidity and transmits pH levels to a recording device worn on the wrist.
- The capsule falls off after a 4 to 10 days and moves down through gastrointestinal tract. It is then expelled with a bowel movement and flushed down the toilet.
How to Prepare for the Test
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
- H2 blockers
- Proton pump inhibitors
DO NOT stop taking any medicine unless told to do so by your provider.
How the Test will Feel
You briefly feel like gagging as the tube is passed through your throat.
The Bravo pH monitor causes no discomfort.
Why the Test is Performed
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.
Do you feel a burning in your chest not long after you eat or lie down? If so, you may have Gastroesophageal reflux disease, or GERD. When we swallow food, it travels down our esophagus into the stomach, where it's greeted by a rush of Hydrochloric acid in the stomach to begin digestion. This acid is so powerful, it could eat the paint right off your car! Fortunately, there's a band of muscle between the stomach and the esophagus - called the Lower Esophageal Sphincter or L-E-S, that clamps down to prevent the stomach contents from moving or refluxing upward and burning the lining of the esophagus. If that band of muscle does not adequately clamp down, this backwash causes the irritation and burning that's known as heartburn or GERD. Maintaining good tight L-E-S muscle tone is the key to preventing this condition. Causes of GERD include being overweight, smoking, and drinking too much alcohol. Certain foods, like chocolate and peppermint and if you're a woman, pregnancy can bring on GERD. To determine if you have GERD, your doctor may request an upper endoscopy exam to look into your esophagus and stomach to diagnose reflux. Other tests can measure the acid and amount of pressure in your esophagus, or if you have blood in your stool. If you do have GERD, lifestyle changes can help. First, avoid foods that cause problems for you and avoid eating large meals. If you're a little on the heavy side, try to lose some weight. Since most GERD symptoms are experienced lying down in bed, let gravity help. Elevating the head of your bed 4 to 6 inches using blocks of wood may help. If symptoms continue, see your doctor or a Gastroenterologist for evaluation and an upper endoscopy exam. Your doctor may suggest you take over-the-counter antacids or may prescribe stronger medications. Call your doctor if you are bleeding, feel like you are choking, have trouble-swallowing, or experience sudden weight loss. The good news is most people who have GERD do not need surgery. For the worst cases, surgeons may perform a laparoscopic procedure to tighten a weak L-E-S muscle. If you have occasional heartburn, antacid tablets can be used as needed. However! If you're having heartburn more than 3 to 4 times a week, see your doctor & take the prescribed medication to prevent this condition.
Normal value ranges may vary depending on the lab doing the test. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Increased acid in the esophagus may be related to:
- Barrett esophagus
- Difficulty swallowing (dysphagia)
- Esophageal scarring
- Gastroesophageal reflux disease (GERD)
- 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
Falk GW, Katzka DA. Diseases of the esophagus In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 129.
Kavitt RT, Vaezi MF. Diseases of the esophagus.In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 68.
Richter JE, Vaezi MF. Gastroesophageal reflux disease. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 46.
Last reviewed on: 10/29/2020
Reviewed by: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.