pH Testing

Patient Information

The pH test for acid reflux measures how often and for how long stomach acid enters the esophagus, and how well it clears the esophagus. Done 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 done to evaluate less common symptoms of GERD such as chest pain, asthma, hoarseness, and more.

Diagnostic Tests

Before doing any testing, your doctor 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. She will also ask you about your risk factors for GERD including whether you have a hiatal hernia, if you smoke, or if you take medications or eat foods which could predispose you to reflux.

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 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 doctor may then recommend pH monitoring (the focus of this article.)

Other tests that are done less often may include a barium swallow or esophageal manometry.

What to Expect

If your doctor recommends an endoscopy, she will have you set up a time to do the procedure, usually in the endoscopy suite at the hospital or in a free-standing endoscopy clinic. She will advise you that the procedure can be a little uncomfortable, but is usually tolerated quite well.

You should talk to your doctor about any medications you take well before your procedure, as some of these may interfere with your results. It is far too common for people to show up on the day of the procedure, but have to reschedule it since these medications were not held. Make sure to talk about medications such as proton pump inhibitors (such as Prilosec or omeprazole), H2 blockers (such as Zantac or ranitidine), antacids, steroids, calcium channel blockers, and nitrates. Sometimes a medication can be continued, but your doctor 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 doctor will usually place an IV and give you a medication to relax you. She may also spray the back of your throat with a medication. When you are relaxed there are two ways in which she can place the probe in your body. The first way is a bit low-tech: The doctor inserts a tubular probe through your nose and into your esophagus. The tube stops just above the lower esophageal sphincter (LES.) 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.

The second way is a bit more high-tech: With an endoscope, the doctor places a disposable capsule into the lining of your esophagus. 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 way, you will be keeping a record of any suspected acid reflux issues, and other symptoms, such as coughing and wheezing. This can help the doctor 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 doctor'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.

You 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 be due to a few different things, ranging from GERD to esophagitis, to scaring (fibrosis), to Barrett's esophagus. At your visit, your doctor will discuss what this means to you and talk about whether further testing is needed to define the condition.

Depending on your results, your doctor may make recommendations as to lifestyle changes she recommends as well as medications to ease your symptoms and prevent complications.

Bottom Line

The esophageal pH test is done to look for the presence of acid reflux, most often when the results of an upper endoscopy are normal. The procedure takes place much like an endoscopy and is usually well tolerated. In order for the results of the test to be accurate, it's important to talk to your doctor about all medications you use, and some, such as proton pump inhibitors and antacids will probably be discontinued prior to the test.


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Winfield Woods: 9150 E.  109th Ave., Ste 2D, Crown Point, IN 4630 

Marcotte Medical: 16000 W.101st Avenue, Dyer IN 46311 

Leetsma Healthcare : 519 N. Halleck St. DeMotte IN 46310 

Ph: (219) 922-4900

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