On this page
At a glance
- A thin, flexible catheter passes through the nose into the esophagus and stays in place for about 24 hours.
- It detects reflux regardless of acidity, so it can show reflux that medication hasn’t stopped.
- It is often performed while you continue your PPI, to understand persistent symptoms.
- It can also help identify belching and rumination patterns that mimic reflux.
How impedance works
Tiny sensors along the catheter measure how easily a small electrical current passes between them. Liquid, gas, and the lining itself conduct differently, so the recording shows each time something moves up or down the esophagus — and how high it travels. A pH sensor on the same catheter shows whether it was acidic.
This matters because PPIs make reflux less acidic, but they don’t stop reflux from happening. Someone who still has regurgitation or cough on a PPI may have ongoing, weakly acidic reflux that a pH-only test would miss.
When it is used
The ACG guideline recommends impedance-pH monitoring on PPI therapy for people with established GERD whose symptoms persist despite treatment. It helps answer whether the remaining symptoms are still caused by reflux — information that shapes decisions about surgery, which controls reflux regardless of acidity.
It is also used to investigate excessive belching, rumination, and other patterns that can be confused with reflux. The Lyon consensus adds supporting measures from impedance testing, such as the number of reflux episodes and a measure of lining health called mean nocturnal baseline impedance, to help interpret borderline acid results.
What the test is like
The catheter is placed through the nose after numbing medicine, often after manometry has been used to locate the valve. You go home wearing a small recorder and return the next day. Most people find the first few minutes uncomfortable and then adapt; talking, eating, and sleeping are possible with it in place.
As with Bravo testing, you’ll record symptoms, meals, and times lying down. Try to eat and do what you normally would, so the recording reflects a typical day.
Bravo or impedance-pH?
Neither test is “better”; they answer different questions. The comparison in the question below explains how they’re chosen.
Common questions
What’s the difference between Bravo and 24-hour impedance-pH testing?
Bravo is wireless, records acid for up to four days, and is best for proving whether GERD exists; impedance-pH uses a nasal catheter for about 24 hours and detects non-acid reflux too, which makes it useful for symptoms that persist on medication.
| Feature | Bravo wireless pH | Impedance-pH |
|---|---|---|
| How it’s placed | Capsule attached during endoscopy | Thin catheter through the nose |
| How long it records | Up to 96 hours | About 24 hours |
| What it detects | Acid | Acid and non-acid reflux, and how high it travels |
| Typical use | Is GERD present? (usually off medication) | Why do symptoms continue on medication? Belching or rumination? |
Longer recordings capture day-to-day variation, which is why wireless monitoring is preferred for proving GERD. Impedance testing is chosen when the question is about reflux that medication hasn’t stopped.
Sources
- Katz PO, et al. ACG Clinical Guideline for the Diagnosis and Management of GERD. Am J Gastroenterol. 2022;117(1):27–56.
- Gyawali CP, et al. Updates to the modern diagnosis of GERD — Lyon consensus 2.0. Gut. 2024;73(2):361–371.
- Yadlapati R, et al. AGA Clinical Practice Update on the Personalized Approach to the Evaluation and Management of GERD. Clin Gastroenterol Hepatol. 2022;20(5):984–994.
This page is general education. It can’t account for your history, test results, or other conditions, so please discuss your situation with your own clinician.