This test measures how much acid comes up from the stomach into the gullet over a full day and night, and whether the symptoms you notice actually happen at the same time as the reflux. A thin sensor stays in place for 24 hours while you go about your normal day.

What it is, and why you are having it

Reflux symptoms are common, but heartburn and chest pain have many causes, and treating the wrong one wastes years. This test settles the question. It records every reflux episode, measures the total time acid is in contact with the lining of the gullet, and lets us match your own symptoms against the recording — you press a button each time you feel one.

It is done when reflux is suspected but endoscopy is normal and the diagnosis has not been proved, when symptoms persist despite proper acid treatment, before anti-reflux surgery, and when a chronic cough, hoarseness or a lump-in-the-throat sensation may be caused by reflux. Impedance is an extra measurement on the same tube that also detects reflux which is not acidic.

On or off acid tablets

Which one applies to you depends on the question being asked, and getting this wrong wastes the test. If reflux has never been proved, the study is done OFF acid tablets — and that remains true even if your symptoms are continuing despite treatment. It is done ON the tablets, at the proper dose and timing, only when reflux has already been demonstrated: by inflammation seen at endoscopy, by Barrett’s oesophagus, or by an earlier abnormal pH study done off treatment, and the question now is why symptoms persist. Your appointment letter will say which. If it is not clear, telephone the laboratory before you stop anything.

1 the tube taped to the cheek · 2 the sensor, a set distance above the lower valve · 3 stomach · 4 the recorder you wear, with the buttons you press

Getting ready

• Have nothing to eat from midnight the night before. You may take small sips of water until two hours before the tube is passed.
• Take your other regular medicines as usual. If you take insulin or tablets for diabetes, telephone the endoscopy unit before the appointment so the dose can be adjusted around the fast.
• For a study OFF acid tablets: stop proton pump inhibitors — omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole — for at least 7 days, which is what the guidelines require. This unit prefers 14 days where symptoms allow; your appointment letter will say which applies to you. Stop H2 blockers such as famotidine or nizatidine for 3 days, and antacids and alginates such as Gaviscon for 24 hours.
• Medicines that change how the gullet moves — prokinetics such as metoclopramide or domperidone — should also be stopped for 48 hours if it is safe for you to stop them. Ask the endoscopy unit if you are not sure.
• For a study ON acid tablets: keep taking them exactly as prescribed, at the right times, and do not miss a dose.
• A manometry test is normally done first, on the same day or before, so that the sensor is positioned correctly. See sheet PE-PROC-13.

On the day

No sedation is used. A very thin flexible tube is passed through one nostril into the gullet — the same passage as for manometry, taking a few minutes. It is then taped to your nose and cheek and connected to a small recorder that you wear on a shoulder strap or belt.

You go home with it. The point of the test is to record an ordinary day, so eat your usual meals, sleep normally, and do your usual activities. Keep the recorder away from water — no shower or bath while it is on.

You will be given a diary. Every time you feel a symptom, press the button on the recorder and write down the time and what the symptom was. You also record when you eat and when you lie down. This diary is what allows us to link your symptoms to the recording, and the test is much less useful without it.

You return at an agreed time the next day for the tube and recorder to be removed. That takes a few seconds.

What are the risks?

There are essentially no risks. The tube is uncomfortable when it goes in, and most people are aware of it in the throat for the first hour or two and then largely forget it. A little nosebleed or a sore throat is possible. Some people sleep less well with the tube in.

Afterwards

You can eat, drink and drive normally as soon as the tube is out. Restart your acid tablets straight away unless you have been told otherwise.

The 24 hours of recording have to be analysed alongside your diary, so the result is not available on the day. It goes to the doctor who requested it and is discussed at your clinic appointment.

This leaflet is general information and does not replace advice from your own doctor.