Most people with reflux never need a test. When the symptoms are typical and there are no warning signs, a doctor can diagnose GERD from what you describe and start treatment. Tests are used when symptoms are unusual, do not respond to treatment, or when surgery is being considered.
See a doctor promptly if you have:
- difficulty swallowing, or food sticking
- weight loss you cannot explain
- vomiting blood or coffee-ground material, or black, tarry stools
- persistent vomiting
- unexplained anaemia
- new or persistent indigestion or reflux when you are 55 or over, especially with weight loss
These signs mean you should have an endoscopy first, rather than just trying medicine.
The usual path to a diagnosis
1. Talking to your doctor
Your doctor will ask about your symptoms, when they happen, what makes them better or worse, your medicines, smoking and alcohol, and whether you have any warning signs. It helps to bring notes. The symptom diary can print a summary to take to your appointment.
2. A trial of treatment
If you have typical heartburn or regurgitation and no warning signs, guidelines recommend an eight-week trial of a once-daily PPI taken before a meal, alongside lifestyle changes. If symptoms clearly improve, that supports the diagnosis. If they do not, the next step is usually testing rather than higher doses. A PPI trial is a practical step, not proof: some people improve for other reasons, and some people with GERD respond only partly.
3. Tests when needed
Tests are recommended when there are warning signs, when symptoms do not respond to a PPI trial or return after stopping, when the main symptoms are outside the oesophagus (such as cough or hoarseness without heartburn), and before any reflux surgery or procedure.
The tests explained
Upper GI endoscopy (gastroscopy)
What happens: a thin, flexible tube with a camera is passed through your mouth into the oesophagus, stomach and first part of the small intestine. It takes 5 to 15 minutes. You can usually choose a throat spray, sedation or both. You will be asked not to eat for about six hours beforehand.
What it shows: inflammation (oesophagitis), Barrett's oesophagus, narrowing (stricture), hiatus hernia, ulcers and other conditions. Small tissue samples (biopsies) can be taken painlessly. Many people with GERD have a normal-looking oesophagus; this is called non-erosive reflux disease and does not mean nothing is wrong.
Tip: to look for reflux damage, doctors may ask you to stop your PPI for two to four weeks beforehand, if it is safe to do so. Follow the instructions you are given.
Reflux monitoring (pH or pH-impedance testing)
What happens: this measures how often and for how long acid reaches the oesophagus. There are two main types:
- Catheter test: a thin tube is passed through the nose into the oesophagus and connected to a small recorder for 24 hours. Impedance sensors on the tube also detect non-acid reflux.
- Wireless capsule: a small capsule is attached to the oesophagus during an endoscopy and records for up to 96 hours, then falls off and passes naturally.
You go about your normal day, eat normally, and press a button or note when you have symptoms.
What it shows: the percentage of time the oesophagus is exposed to acid, and whether your symptoms line up with reflux episodes. International criteria (the Lyon Consensus) treat acid exposure above 6% of the time as conclusive evidence of GERD and below 4% as normal. It is the key test before surgery and when the diagnosis is unclear.
Oesophageal manometry
What happens: a thin tube through the nose measures pressure along the oesophagus while you swallow small sips of water. It takes about 20 to 30 minutes.
What it shows: how well the oesophagus squeezes food down and how strong the LOS is. It does not diagnose GERD itself, but it is needed before reflux surgery to rule out problems such as achalasia that would make surgery unsafe.
Barium swallow
What happens: you drink a chalky liquid while X-rays are taken.
What it shows: the shape of the oesophagus, narrowing and large hiatus hernias, and how swallowing works. Guidelines advise against using it on its own to diagnose GERD, because seeing reflux on an X-ray is neither reliable nor specific.
Understanding your results
Oesophagitis grades (Los Angeles classification)
If endoscopy shows inflammation, it is usually graded from A (mildest) to D (most severe):
| Grade | What the doctor sees |
|---|---|
| A | One or more small breaks in the lining, each no longer than 5 mm |
| B | At least one break longer than 5 mm, not joining up across the folds of the lining |
| C | Breaks joining up across folds, covering less than three-quarters of the circumference |
| D | Breaks covering three-quarters or more of the circumference |
Grades B, C and D are considered conclusive evidence of GERD. People with grade C or D usually need long-term PPI treatment and a repeat endoscopy after healing to check for Barrett's oesophagus.
When the results are normal
If endoscopy and reflux monitoring are both normal, but you still have heartburn, your doctor may diagnose functional heartburn (the oesophagus is oversensitive without excess reflux) or reflux hypersensitivity (normal amounts of reflux trigger symptoms). These are real conditions with their own treatments, often medicines that reduce nerve sensitivity, and they are a reason to reassess long-term PPI use.
Barrett's oesophagus
If the lining has changed to a different cell type, you may be offered regular check-up endoscopies. See Barrett's oesophagus.
Getting the most from your appointment
What to tell your doctor
- your main symptoms, how long you have had them, and how often they happen
- what makes them better or worse, including foods, meal times and sleep
- every medicine and supplement you take, including over-the-counter ones
- how you have been taking any reflux medicine (dose and timing)
- any warning signs, family history of oesophageal or stomach cancer, smoking and alcohol
Questions to ask
- Do my symptoms sound like GERD, or could something else be going on?
- Do I need any tests, and why?
- How and when should I take my medicine, and for how long?
- What should I do if the treatment does not help?
- Which symptoms should make me come back sooner?
Sources
- Katz PO, Dunbar KB, Schnoll-Sussman FH, et al. ACG Clinical Guideline for the Diagnosis and Management of Gastroesophageal Reflux Disease. Am J Gastroenterol. 2022;117(1):27-56.
- Yadlapati R, Gyawali CP, Pandolfino JE. AGA Clinical Practice Update on the Personalized Approach to the Evaluation and Management of GERD: Expert Review. Clin Gastroenterol Hepatol. 2022;20(5):984-994.
- NICE. Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management (CG184). National Institute for Health and Care Excellence, 2014, updated 2019.
- Gyawali CP, Yadlapati R, Fass R, et al. Updates to the modern diagnosis of GERD: Lyon consensus 2.0. Gut. 2024;73(2):361-371.
- Fitzgerald RC, di Pietro M, Ragunath K, et al. British Society of Gastroenterology guidelines on the diagnosis and management of Barrett's oesophagus. Gut. 2014;63(1):7-42.