What to Expect From the pH Test for Acid Reflux

If your healthcare provider has recommended a pH monitoring test for acid reflux, what can you expect? What happens before, during, and after the procedure, and what does it mean if your results are abnormal?

The pH Test

The pH test for acid reflux (gastroesophageal reflux disease or GERD) measures how often and for how long stomach acid enters the esophagus, and how well it clears the esophagus. Performed with a thin, plastic tube armed with a sensor, it measures the amount of acid backing up into the esophagus.

This procedure is often done when GERD symptoms are present but an endoscopy exam doesn't detect any evidence of reflux disease. It may also be used on patients for whom the standard therapy of a twice-daily dose of proton pump inhibitors (PPIs) does not add any benefit. It can also be helpful to evaluate less common symptoms of GERD such as chest pain, asthma, hoarseness, and more.

Diagnostic Tests

Before doing any testing, your healthcare provider will ask you about your symptoms of GERD. The most common of these is heartburn. Other symptoms may include nausea or abdominal pain, difficulty swallowing, or a chronic cough.

Your healthcare provider will also ask you about your risk factors for GERD, including whether you have a hiatal hernia, smoke, or take medications or eat foods that could predispose you to reflux.

heartburn diagnosis
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Often times the diagnosis of GERD is made on symptoms alone (a clinical diagnosis.) If the diagnosis is uncertain, or if your symptoms are chronic and there is a concern that you could develop complications of GERD, further testing is recommended.

Testing is often done as well if you fail to respond to lifestyle changes and medications. At the current time, the most common test is an upper endoscopy. This is a procedure in which a tube is passed through your mouth and into your esophagus and stomach.

Biopsies of any abnormalities can be taken. If no abnormalities are found, your healthcare provider may then recommend pH monitoring. Other tests that are done less often may include a barium swallow or esophageal manometry.

What to Expect

If your healthcare provider recommends an endoscopy, this will usually take place in the endoscopy suite at the hospital or in a free-standing endoscopy clinic. The procedure can be a little uncomfortable but is usually tolerated quite well.

Make sure to talk about medications such as proton pump inhibitors (such as Prilosec or omeprazole), H2 blockers (such as ranitidine), antacids, steroids, calcium channel blockers, and nitrates. Sometimes a medication can be continued, but your healthcare provider needs to be aware of these as they may affect the pH test outcome.

Before Your Test

You will be instructed not to eat for four to six hours prior to your procedure. As noted, you should not take your regular acid reflux medications such as proton pump inhibitors or antacids prior to the test.


If you are having the pH test at the same time as an endoscopy, your healthcare provider will usually place an IV, give you a medication to relax you, and may also spray the back of your throat with a medication. When you are relaxed there are two ways in which your healthcare provider can place the probe in your body.

With a tube

Your healthcare provider will insert a tubular probe through your nose and into your esophagus, stopping just above the lower esophageal sphincter. This may occur during endoscopy by clipping a pH monitoring device to the lining of the esophagus. The tube is then left in place for 24 hours. During that time, you are encouraged to engage in normal activities.

With a capsule

Your healthcare provider requests that you swallow a disposable capsule—about the size of a large pill—that will travel down through your esophagus, stomach, and intestine. It wirelessly records data about symptoms and when you eat or lie down to a unit that you wear on your belt with a touch of a button.

Either method facilitates keeping a record of any suspected acid reflux issues, and other symptoms, such as coughing and wheezing. This can help the healthcare provider determine if acid reflux is related to unexplained asthma or other respiratory symptoms.

While you are having esophageal pH monitoring you will be instructed to eat regular meals and to resume your normal activities. You usually should not lie down, however, until you go to sleep for the night.


After your test, your throat may feel a little sore for a day or so. Sucking on lozenges or hard candy may be soothing. Later on, at your next healthcare provider's appointment, you should receive the results of your esophageal pH test.


Most of the time people go home after the test and will have an appointment scheduled at which time they will hear about the results of the pH test.

Your pH monitoring may reveal that your pH is normal, in which case another type of testing may be recommended. If there is increased acid in your esophagus it could present as a few different conditions, ranging from esophagitis, to scarring (fibrosis), to Barrett's esophagus. These issues are a consequence of increased acid exposure to the esophagus. At your visit, your healthcare provider will discuss what this means and whether further testing or treatment is needed.

Depending on your results, your healthcare provider may recommend lifestyle changes as well as medications to ease your symptoms and prevent complications.

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Article Sources
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  1. National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & causes of GER & GERD. 2014.

  2. National Institute of Diabetes and Digestive and Kidney Diseases. Diagnosis of GER & GERD. 2014.

  3. Cleveland Clinic. GERD: 24-Hour esophageal pH test: test details. Updated May 13, 2016.

  4. Wang RH. From reflux esophagitis to Barrett's esophagus and esophageal adenocarcinoma. World J Gastroenterol. 2015;21(17):5210-9. doi:10.3748/wjg.v21.i17.5210

  5. National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for GER & GERD. 2014.