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pH & impedance testing


  1. Do not eat or drink for at least 8 hours before the exam. After the exam you may eat and drink normally.

  2. Stop 7 days before the study: Prilosec (omeprazole), Nexium (esomeprazole), Aciphex (rabeprazole),

    Prevacid (lansoprazole), Protonix (pantoprazole), Zegerid (immediate release omeprazole), Kapidex (dexlansoprazole). Stop 2 days before the study: Zantac (Randitidine), Tagamet (Cimetidine), Axid (Nizatidine), Pepcid (Famotidine).

  3. Do not take your morning medications; however, bring them with you, as you will be able to take them after the exam. This is because certain medications may interfere with the test.

  4. Bring a list of all your medications.

  5. You will not be sedated for this procedure.

  6. The pH catheter placement and teaching will usually take 10 minutes

  7. You will not need an escort.

  8. Remember to bring your BC Care Card and government identification with you.



Esophageal pH monitoring evaluates for gastroesophageal reflux disease and to determine the effectiveness of medications that prevent acid reflux or to test before surgery. This test measures the amount of acid refluxing or backing up from the stomach into the esophagus (food pipe). Esophageal pH monitoring is used in several situations to assess for gastroesophageal reflux disease (GERD). The first is to evaluate typical symptoms of GERD such as heartburn and regurgitation that do not respond to treatment with medications. In this situation, there may be a question whether the patient has gastroesophageal reflux disease or whether antacid medications are adequate to suppress acid production. The second is when there are atypical symptoms of GERD such as chest pain, coughing, wheezing, hoarseness, sore throat. In this situation, it is not clear if the symptoms are due to gastroesophageal reflux. Occasionally, this test can be used to monitor the effectiveness of medications used to treat GERD. The test is often used as part of a pre-operative evaluation before anti-reflux surgery.


Combined pH/impedance monitoring also allows detection of acid and non-acid reflux; a small catheter is placed through your nose into your food pipe and is removed at a return visit in 24 hours. In order to determine the correct placement of the pH/impedance catheter, it may be necessary to perform a short test called esophageal manometry. Placing the catheter takes approximately 10 minutes and no sedation is necessary. The small catheter comes out the nose and is connected to a small battery-powered recorder. You go home with the catheter and recorder in place. Please go about your usual activities: eating, sleeping, and working. You record meals, sleep, and symptoms in a diary and by pushing buttons on the recorder. The diary helps the doctor to interpret the results. You return the next day for removal of the catheter at the same time as your original EFT lab appointment. After the pH catheter is removed, the recorder is attached to a computer so that the data recorded can be downloaded into the computer where it is then analyzed.


Esophageal pH/impedance testing provides clear documentation of acid and non-acid reflux. With this information, your doctor can provide a specific treatment program as well as reassurance if the exam is normal.


The side-effects of pH/impedance testing are minor and may include mild sore throat, temporary irritation of the nasal passages, and nose bleeds. Occasionally, during insertion, the tube may enter the larynx (voice box) and cause coughing. When this happens, the problem is recognized immediately, and the tube is rapidly removed.

pH & impedance testing: Articles & Resources
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