24-hour pH / impedance monitoring (Ambulatory 24-hour oesophageal pH and impedance monitoring)
A test that records how much acid and fluid comes up from the stomach into the gullet over 24 hours or more, used to confirm reflux and link it to your symptoms.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- The test records how much acid and fluid reflux into the gullet over 24 hours or more, and links it to the symptoms you note in a diary.
- It is mainly used to confirm reflux when the diagnosis is uncertain, when symptoms do not respond to treatment, or before anti-reflux surgery.
- Whether you stop or continue your acid-reducing tablets depends on the question being asked — follow the unit's instructions carefully, as it strongly affects the result.
- A wireless capsule version avoids a nasal tube and records for longer, but is fitted during a gastroscopy; results take days to a couple of weeks either way.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Confirms whether troublesome symptoms are really caused by reflux
As a way to look at the lining of the gullet, which needs a camera test instead.
You carry on with normal activities and meals, press the button and note your symptoms in the diary, and keep the recorder with you. The catheter is taped...
Clear advice on restarting any paused acid-reducing or other medicines.
You carry on with normal activities and meals, press the button and note your symptoms in the diary, and keep the...
For the catheter, you return to the clinic to have it removed and to hand back the recorder and diary. The capsule...
The recording is downloaded and analysed alongside your symptom diary, looking at how much reflux occurred and...
Your referring clinician explains what the recording showed, in the context of your symptoms and any other tests...
What is 24-hour pH / impedance monitoring?
This test records how often acid, and sometimes other stomach contents, come up from the stomach into the gullet (oesophagus) over a period of time — usually 24 hours. A thin tube with sensors is passed through the nose and positioned in the gullet, with the end taped to your cheek and connected to a small recorder you carry. You press a button and keep a diary when you have symptoms, so the test can link them to any reflux happening at that moment.
'pH' refers to acidity, so the test measures how much acid refluxes. 'Impedance' detects the movement of fluid and gas, so it can also pick up non-acid reflux. Together they give a detailed picture of reflux and how it relates to your symptoms.
The test is used to confirm whether troublesome symptoms are really due to reflux, especially when the diagnosis is uncertain, when symptoms do not respond to acid-reducing tablets, or before anti-reflux surgery. Whether you stay on or stop your acid-reducing medication for the test depends on the question being asked, so the unit will give you specific instructions.
There is also a wireless 'capsule' version, which is clipped onto the gullet lining during a gastroscopy and records for longer, avoiding a nasal tube. The test gathers information about reflux; it does not look at the lining in detail or treat anything.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Nasal catheter compared with wireless capsule
| Nasal catheter | Wireless capsule | |
|---|---|---|
| How it sits | Tube through the nose | Capsule clipped in the gullet |
| Fitted by | Passed at the clinic | During a gastroscopy |
| Recording length | Usually 24 hours | Often up to ~96 hours |
| Detects non-acid reflux | Yes (with impedance) | Usually acid only |
| Main downside | Visible tube, can feel strange | Needs a gastroscopy; chest discomfort possible |
The right choice depends on the question being asked and what your unit offers. A nasal catheter with impedance is often preferred when non-acid reflux matters or when you are on acid-reducing tablets.
Preparing for your test
- Follow the unit's instructions on whether to stop or continue acid-reducing tablets, and for how long — this strongly affects the result, so check carefully.
- Ask about other medicines too, as some antacids and reflux medicines need pausing before the test.
- Follow the fasting instructions — usually no food for a few hours beforehand.
- For the capsule version, follow the gastroscopy instructions, including fasting and arranging an escort home if you have sedation.
- Plan to eat normally and keep to your usual routine during the recording, so it captures a typical day.
- Make sure you understand how to use the symptom button and diary, as matching symptoms to reflux is key.
- Wear clothing that lets you conceal the small recorder, and know when and where to return the equipment.
What happens
For the catheter test, the procedure is usually explained and your nostril may be given a little numbing gel. A thin, soft tube with sensors is passed through your nose and positioned in your gullet, sometimes using a brief manometry first to place it accurately. The tube is taped to your cheek and connected to a small recorder you clip to your waistband or carry.
You then go home and carry on with normal activities and meals. Whenever you have a symptom — such as heartburn, regurgitation, chest discomfort or cough — you press the button and write the time and what you felt in a diary. This lets the team match your symptoms to any reflux at that moment. The recording usually lasts 24 hours, after which you return to the clinic to have the tube removed.
The wireless capsule version is fitted during a gastroscopy: a small capsule is clipped onto the gullet lining and beams readings to a recorder you carry, usually for up to about 96 hours. The capsule falls off by itself after a few days and passes harmlessly. Either way, the recording is then downloaded and analysed alongside your symptom diary before a report is produced.
Is this test right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- As a way to look at the lining of the gullet, which needs a camera test instead.
- When the diagnosis is already clear and the result would not change management.
- People who cannot tolerate a nasal catheter, where the capsule version or another approach may be considered.
- The capsule version may not suit people in whom a gastroscopy or the capsule itself would be unsafe, such as some with swallowing problems or bleeding risks.
Delay or rearrange if…
- Instructions on stopping or continuing acid-reducing tablets have not been followed, as this affects the result.
- You have not been able to fast as advised before the catheter or capsule test.
- You have an active nasal infection, recent nasal surgery or a heavy nosebleed (for the catheter).
- You are too unwell for the test, or for a gastroscopy if the capsule is planned.
- Pregnancy, unless the test is genuinely needed and timing has been discussed.
Alternatives to discuss
- No test, if reflux is already confidently diagnosed or the result would not change treatment.
- A trial of acid-reducing medication, where appropriate, as a simpler first step.
- A gastroscopy to look at the lining of the gullet and stomach.
- Oesophageal manometry, if the main question is about gullet muscle function.
- Specialist review to decide which test, if any, is needed.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Confirms whether troublesome symptoms are really caused by reflux
- Links your symptoms to reflux episodes using the button and diary
- Can detect non-acid as well as acid reflux when impedance is used
- Helps explain why symptoms continue despite acid-reducing tablets
- Provides important information before anti-reflux surgery is considered
- The capsule version avoids a nasal tube and records over a longer period
Risks & complications
- Discomfort or a strange sensation in the nose and throat with the catheter, and the tube being visible
- A mildly sore throat or runny nose during or after the catheter test
- Chest discomfort or a feeling of something in the gullet with the capsule version
- A less useful result if no typical symptoms happen during the recording
- The catheter moving or coming out, sometimes meaning the test has to be repeated
- A minor nosebleed with the catheter
- A non-diagnostic recording if instructions on medication or diary were not followed
- The capsule version needing a gastroscopy, with its own small risks
- The capsule staying attached longer than expected, occasionally needing removal
- A rare gastroscopy complication, such as bleeding or a tear, when the capsule is fitted
- Very rarely, the capsule causing discomfort that means it has to be taken out early
- An inconclusive result, so that other tests are still needed
This is a low-risk test, and the main downsides are discomfort and inconvenience — a visible nasal tube, or chest discomfort with the capsule. The capsule version adds the small risks of a gastroscopy because it is fitted during one. The biggest practical issues are diagnostic: the result depends heavily on following the instructions about acid-reducing medication and on pressing the button and keeping the diary, and the test is most useful when your typical symptoms happen during the recording. Ask whether you should be on or off your tablets, and what happens if no symptoms occur while you are wearing it.
Published figures to discuss
Both versions of the test are low-risk; the catheter test involves no sedation or cuts, and the capsule version carries the small additional risks of the gastroscopy used to fit it. Serious problems are uncommon. The more relevant uncertainty is diagnostic: the result depends on following the medication instructions, on the quality of the recording, and on whether your typical symptoms happen while you are being monitored. Because exact figures depend on the unit and the clinical situation, specific percentages are avoided here.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Physical harm from catheter pH/impedance monitoring | Very low | There is no cut and no sedation for the catheter version. The usual issue is discomfort rather than harm. | Guide sourcesClinical context |
| Nose or throat discomfort, gagging or watering eyes | Common and temporary | Symptoms usually settle once the catheter is in place or soon after it is removed. Patients should still be able to eat and do normal activities unless told otherwise. | Guide sourcesClinical context |
| Oesophageal, throat or nose injury | Very rare | Nosebleed, misplacement or mucosal injury are uncommon. Severe pain, bleeding, breathing difficulty or inability to swallow needs urgent advice. | Impact of high-resolution manometry in the diagnostic workup of GORD — PMCpmc.ncbi.nlm.nih.govSource-linked context |
| Inconclusive or misleading result | Recognised | If symptoms do not occur during the test, acid-suppressing medicines were not managed as instructed, or the diary is incomplete, the result may not answer the clinical question. | Impact of high-resolution manometry in the diagnostic workup of GORD — PMCpmc.ncbi.nlm.nih.govSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no physical recovery from the catheter test beyond a possible mild sore throat. The capsule version has the usual short recovery from a gastroscopy. What matters afterwards is that the recording is downloaded, matched to your symptom diary, and explained to you with a clear plan.
- A mildly sore throat or runny nose for a short time after the catheter
- Some self-consciousness while the tube is visible during the recording
- Chest discomfort or awareness of the capsule for a few days, easing as it passes
- Waiting days to a couple of weeks for the recording to be analysed and reported
- Being asked for a repeat if instructions were not followed or no symptoms occurred
Aftercare
- Return the recorder and your completed symptom diary as instructed, as the diary is key to interpreting the recording.
- Restart any acid-reducing or other medicines only as your team advised.
- You can eat and drink normally once the catheter is removed.
- After the capsule, follow the usual gastroscopy aftercare and report any significant chest pain or swallowing difficulty.
- A simple lozenge or warm drink can ease a mildly sore throat after the catheter.
- Make sure you know who will report the recording and when and how you will get the result.
- Ask what the result will mean for your treatment or any further tests.
- Clear instructions on whether to stop or continue acid-reducing tablets, and for how long
- Fasting instructions understood
- Understanding of how to use the symptom button and diary
- For the capsule, gastroscopy instructions and an escort home if sedated
- Knowing when and where to return the equipment and diary
- Knowing who reports the recording and when results are due
- A point of contact for questions or problems afterwards
⚠ Get urgent help if…
- Severe or worsening chest pain after the test, especially with the capsule
- Difficulty or pain when swallowing, or a feeling that the capsule is stuck
- Vomiting blood, or bringing up material like coffee grounds
- Black, tarry stools after a capsule was fitted
- Difficulty breathing or new shortness of breath
- A nosebleed that will not stop, or a high temperature and feeling very unwell
- Any symptom the unit specifically told you to report — contact them or seek urgent care
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A useful result is a good-quality recording that captures a typical period, ideally including your usual symptoms, so the team can see how much reflux occurred and whether it matched what you felt. Reports often describe the proportion of time acid was present and whether your symptoms lined up with reflux episodes.
The result is interpreted alongside your symptoms and other tests, and alongside whether you were on or off acid-reducing tablets. A normal recording can be reassuring and may suggest symptoms are not due to reflux, but it cannot rule out a problem that simply did not occur during the recording. An abnormal result helps confirm reflux and guide treatment, including whether surgery is suitable. Your clinician should explain what the findings mean for you.
The recording reflects the period you wore it, so its value is tied to what happened during that time and to whether you followed the medication instructions. If your symptoms change, or none occurred during the recording, the test may need repeating or combining with others. Any conclusion is interpreted in the light of your ongoing symptoms and treatment.
Related tests, treatments or support
This test is frequently combined with oesophageal manometry at the same visit, with the manometry used to position the pH sensor accurately. It is usually done after a gastroscopy has looked at the lining of the gullet and stomach, and it is a standard part of the work-up before anti-reflux surgery. Your team should explain how these tests fit together and what each one adds.
Follow-up & long-term care
After the recording, the data is downloaded, analysed alongside your symptom diary, and reported, which takes time. Your referring clinician then explains the findings in the context of your symptoms and any other tests, and what happens next — treatment, surgery planning or further monitoring. You should be told who to contact if you do not hear back or your symptoms change in the meantime.
Repeat, follow-on and what comes next
- If the catheter moves, or instructions were not followed, the test may need repeating.
- If no typical symptoms occur during the recording, the result may be less useful and a repeat or different approach may be suggested.
- Testing may be repeated on and off medication to answer different questions.
- The result is interpreted alongside other tests and may need combining with manometry or a gastroscopy.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Clear advice on restarting any paused acid-reducing or other medicines.
- Interpretation of the recording alongside your symptom diary and other tests, not in isolation.
- A sensible plan if the recording is non-diagnostic, or no symptoms occurred.
- For the capsule version, the usual gastroscopy aftercare and warning-sign advice.
- Clear information on who reports the test, when you get results, and what they mean for treatment.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- Whether the catheter test or the wireless capsule version is used
- Whether the capsule version, fitted during a gastroscopy, includes the endoscopy and sedation costs
- Whether manometry is done at the same visit
- Who downloads, analyses and reports the recording, and how quickly
- Whether it is arranged as part of a consultation or as a stand-alone test
- Any consultation to explain the results and plan next steps
- Further tests the result may lead to, charged separately
- The fee for the test and which version it covers
- For the capsule, whether the gastroscopy and sedation are included
- Whether manometry is included or charged separately
- Whether analysis and a written report are included
- Whether a consultation to explain the results is part of the price
- How quickly the report and results will be available
- What happens, and what it costs, if the recording is non-diagnostic and needs repeating
On the NHS? 24-hour pH and impedance monitoring is available on the NHS in specialist units when clinically indicated; private testing may be used for speed or as part of a reflux assessment.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Not giving clear instructions on whether to stop or continue acid-reducing tablets, which can make the result misleading.
- Not explaining how important the symptom button and diary are to a useful result.
- Not explaining that the capsule version involves a gastroscopy with its own small risks.
- Treating a normal recording as proof there is no problem, when typical symptoms may simply not have occurred.
- Not clarifying which costs are extra in private care, including any combined manometry, the gastroscopy for the capsule, or a repeat test.
Marketing red flags
- Offering the test as a general 'reflux check' without a clear clinical question.
- Not explaining the importance of the medication instructions and symptom diary.
- Implying a normal recording is a complete all-clear regardless of whether symptoms occurred.
- Promoting the capsule version without mentioning that it needs a gastroscopy.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Should I be on or off my acid-reducing tablets for this test, and for how long?
- Will I have the nasal catheter or the wireless capsule, and why?
- Will I have manometry at the same visit?
- What happens if I don't get my usual symptoms while wearing it?
- What will a normal or abnormal result mean for my treatment?
- Who will report the recording, and when and how will I get the result?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my test, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this test not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Should I stop my acid-reducing tablets before the test?
Is the nasal tube uncomfortable?
What is the capsule (Bravo) version?
What if I don't get symptoms while wearing it?
When will I get my results?
Is this test available on the NHS?
Find a verified specialist for 24-hour ph / impedance monitoring
Every consultant is GMC-checked and independently reviewed. Search by postcode and distance, or switch to a map. Ordered by rating, relevance and recency — never by who pays.
No verified consultants list this procedure yet — browse the full directory.
How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: UCLH — Bravo wireless pH monitoring (patient information) North Bristol NHS Trust — Oesophageal manometry and 24-hour pH or impedance monitoring Royal Devon — High-resolution manometry and 24-hour pH/impedance studies (patient leaflet) Impact of high-resolution manometry in the diagnostic workup of GORD — PMC British Society of Gastroenterology — clinical resources
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
Related guides: Oesophageal manometry · Gastroscopy · Reflux (GORD) and heartburn management · Anti-reflux surgery (Nissen fundoplication) · Faecal calprotectin test