24-hour pH monitoring

Why might I need it?

Your doctor might recommend this test if you have symptoms that could be caused by acid reflux, such as:

• heartburn
• a persistent cough
• a sore throat or hoarseness
• bringing up food.

It's also used to confirm reflux before surgery to treat it, or if your symptoms are continuing despite taking reflux medication.

What are the benefits of having it?

This test gives clear evidence of whether acid reflux is really the cause of your symptoms, rather than relying on guesswork. Left untreated, ongoing acid reflux can damage your oesophagus and, rarely, lead to more serious conditions such as Barrett's oesophagus or oesophageal cancer, so an accurate diagnosis matters.

It's equally useful if your results come back normal, since this tells your doctor to look for another cause of your symptoms instead.

Are there different types of test?

Yes, there are a few ways this can be done:

• a thin tube passed through your nose, which stays in place for 24 hours while you wear a small recorder on a belt
• a wireless capsule, sometimes called the Bravo system, attached to your oesophagus during an endoscopy, which can record for longer, usually around 48 hours, without a tube
• impedance-pH monitoring, which measures pH together with a second signal called impedance, so it can also pick up reflux that isn't acidic. This is sometimes used if you're still having symptoms despite taking reflux medication.

Your doctor will recommend whichever option best suits your symptoms and circumstances.

How do I prepare for the test?

Preparation usually includes:

• stopping certain reflux medicines in advance, such as proton pump inhibitors around 10 days before, and other medicines like ranitidine or Gaviscon around 3 days before, unless your doctor tells you to keep taking them
• not eating anything after midnight the night before your test
• not drinking any fluids after 7am on the day of your test
• continuing your other normal medication, apart from antacids
• wearing comfortable, loose clothing.

If you have diabetes, contact your diabetic nurse for advice beforehand, since changes to eating and medication can affect your blood sugar.

What happens during the test?

1. You'll sit upright while a local anaesthetic spray numbs the inside of one nostril
2. A soft, thin tube is then guided in through your nose and down towards the lower end of your gullet, helped along by small sips of water; sedation isn't used for this test
3. Once in place, the tube is taped to your nose and cheek, tucked behind your ear, then linked to a small recorder clipped onto a belt at your waist
4. A member of staff will show you which buttons to press, so you can record when you're eating, when you lie down, and if you notice a symptom
5. Fitting the tube takes around 10 minutes in total, after which you're free to go home and carry on with your day while wearing the recorder.

You can carry on with most normal activities, including work, eating and drinking, while the recorder is in place. At night, you'll take the belt off and keep the recorder next to you or under your pillow instead of wearing it.

During the 24 hours, avoid:

• chewing gum, or having peppermint sweets or drinks
• fizzy drinks
• acidic foods and citrus fruit, such as vinegar, orange juice, lemons or limes
• showering or bathing, since water can damage the recording equipment
• indigestion medication, unless you've been told otherwise, as this can make the results inaccurate and mean the test needs repeating.

What happens after the test?

After 24 hours, you'll go back to have the tube taken out, which is quick and usually takes 5 to 10 minutes.

If you find you can't cope with the tube before the 24 hours are up, you can remove it yourself by taking off the tape and gently pulling it out, then return it and the recorder to the hospital. Doing this means there may not be enough information to complete the test.

Your results are sent to the consultant who referred you for the test, and you'll usually discuss them at your next outpatient appointment.

What are the risks?

Like any procedure, this test carries some risks, though serious problems are rare:

• common, short-lived effects include a runny nose while the tube is inserted, a sore throat for up to 24 hours, and slight discomfort when swallowing
• some people feel faint during the procedure
• there's a very small risk of bleeding from damage to the inside of your nose, throat, voice box, oesophagus or stomach
• rarely, the tube can trigger an irregular heartbeat as it's inserted, or cause vomiting that's then breathed in.

Your doctor or specialist nurse will monitor you closely so that any problems are picked up and treated quickly.