What is pH & Impedance Testing?
pH and impedance testing is an advanced test used to measure reflux from the stomach into the oesophagus over an extended period, usually while you continue your normal daily activities.
Unlike pH testing alone, impedance monitoring can detect the movement of liquid and gas within the oesophagus, allowing the test to identify both acidic and non-acidic reflux.
A thin catheter containing specialised sensors is passed gently through the nose and positioned in the oesophagus. The catheter is connected to a small portable recorder that collects information throughout the monitoring period.
This allows your gastroenterologist to determine how often reflux occurs and whether episodes correspond with your symptoms.
Why pH & Impedance Testing is done
Your gastroenterologist may recommend this test to investigate:
- Persistent heartburn or acid reflux symptoms
- Regurgitation
- Symptoms that continue despite reflux treatment
- Chronic cough
- Throat clearing or unexplained throat symptoms
- Reflux symptoms when previous tests have been inconclusive
- Suspected non-acid reflux
- Symptoms that may or may not be related to GERD
- Reflux evaluation before or after certain treatments or procedures
Because impedance testing can identify both acidic and non-acidic reflux, it can provide valuable information when standard acid testing alone does not fully explain a patient’s symptoms.
How to prepare
Your care team will provide specific instructions based on the reason for your test. You may be asked to:
- Avoid eating or drinking for a specified period before catheter placement
- Temporarily stop certain acid-suppressing medications — only if instructed by your doctor
- Continue reflux medication if your doctor wants to assess symptoms while you are receiving treatment
- Bring a list of your current medications
- Wear comfortable clothing
- Bring your referral and any relevant previous test results
Whether reflux medication should be stopped or continued depends on the purpose of the study, so please follow the instructions provided specifically for you.
During the test & your results
A thin, flexible catheter is gently passed through your nose and positioned in the oesophagus. It is connected to a small portable recorder that you carry with you during the monitoring period.
You will generally be encouraged to continue your normal routine, including eating, drinking, sleeping and carrying out usual activities, unless your care team advises otherwise.
You will be asked to record important events such as meals, lying down and symptoms. This allows your gastroenterologist to compare your symptoms with episodes of acid or non-acid reflux.
Once monitoring is complete, the catheter is removed and the recorded information is analysed. Your gastroenterologist will explain whether significant reflux was detected, whether it corresponds with your symptoms, and what treatment or further investigation may be appropriate.
