24hr pH / Impedance Monitoring Study

What is a 24-Hour pH / Impedance Test?

Patients with chronic heartburn or other suspicions for gastro-oesophageal reflux disease (GORD) may be asked to undergo a 24-hour pH / Impedance test.  This examination quantitatively measures the amount and chemical nature of reflux episodes during a 24-hour period.  It can help differentiate between different types of oesophageal reflux episodes (acid vs. non-acid).  The test also allows your doctor to correlate your symptom(s) to those episodes of reflux for better symptom management.


  • A local anaesthetic spray is used to numb the nose and throat.
  • A slimline catheter is passed through one nostril, down the oesophagus and into the lower oesophagus / gut. Once in place, the tube is taped to your nose.
  • The catheter connects to a small data receiver, which is worn over your shoulder for the duration of the test.
  • During the study, you will be asked to keep a diary of when you eat, sleep, and any symptoms that you experience.  These symptoms will then be analysed along with the information collected from the receiver.
  • You can perform your normal daily activities whilst wearing the monitor, however, you are not able to shower or bathe.
  • Please be aware that the catheter will be visible during the test. 
  • You will be required to return approximately 24 hours after the completion of your procedure, to have the catheter removed or return the data recorder (if removing independently).


To ensure a successful test, please follow all instructions carefully.  Failure to accurately and completely prepare for your procedure may result in the need to repeat the test.

7 days prior to procedure:

  • Several medications alter the pH level of the stomach (by blocking acids) and must be discontinued, unless otherwise instructed; all other usual medications may be continued.
    • Losec® (Omeprazole)
    • Pariet® (Rabeprazole)
    • Somac® (Pantoprazole)
    • Nexium® (Esompeprazole)
    • Zoton® (Lansoprazole)
    • Zantac® (Ranitidine)
    • Pepcidine® (Famotidine)
    • Tazac® (Nizatidine)

24 hours prior to procedure:

  • Stop taking all ‘over-the-counter’ antacids (eg. Gaviscon, Mylanta®, QuickEze, Tums®)

Day of the procedure:

  • Please fast for 4 hours prior to your appointment.  Sips of water are okay.
  • Please advise staff at the time of booking if you are diabetic, as your preparation may be slightly different.