H. pylori breath test vs gastroscopy

The breath test answers a narrow question: is H. pylori present in the stomach? This bacterium can cause gastritis and ulcers and is linked to stomach cancer. In people with indigestion, a "test and treat" approach can resolve symptoms in some and prevent ulcers.

Gastroscopy answers a broader question: what does the stomach and upper gut look like, and is there an ulcer, tumour or other structural problem? It is more invasive, so it is reserved for those who need that level of answer.

You swallow a drink or tablet containing urea labelled with a harmless carbon isotope. If H. pylori is present, its enzyme splits the urea, releasing labelled carbon dioxide that appears in your breath, which you blow into a bag or tube. It takes a short time and involves no radiation or needles.

It must be done after proper preparation, because stomach-acid-reducing medicines such as proton pump inhibitors and some antibiotics can suppress the bacteria and cause a false negative. You will be told how long to stop them, and you should not do this without medical guidance if you rely on them for serious conditions.

Gastroscopy requires fasting, throat spray or sedation, and a camera passed through the mouth. It lets the doctor see ulcers and cancers, take biopsies and test them for H. pylori at the same time, and sometimes treat bleeding. Its downsides are invasiveness, small risks and limited capacity.

It is often performed within urgent pathways for people with alarm symptoms, or when symptoms continue despite treatment, rather than as a first test for simple indigestion.

NICE guidance on dyspepsia and gastro-oesophageal reflux (CG184) recommends testing for H. pylori in people with dyspepsia and treating if positive, and offering endoscopy to people with alarm signs. NICE suspected cancer guidance (NG12) sets out which upper gut symptoms need urgent endoscopy referral, including difficulty swallowing at any age.

The reasoning is proportionality: most indigestion is benign and responds to a non-invasive approach, while the minority with alarm features need direct examination without delay.

• Recurrent indigestion with no alarm features: discuss H. pylori testing with your GP, who will advise on medicines before the test.

• Difficulty swallowing, vomiting blood, black or tarry stools, unexplained weight loss or anaemia: urgent assessment; gastroscopy is likely. Vomiting blood or black stools may need 999 or A&E.

• Persistent symptoms after H. pylori treatment: gastroscopy may be considered.

• Planned gastroscopy for another reason: biopsies can test for H. pylori at the same time.

• Need for proof of eradication after treatment: a breath test is commonly used, at least a few weeks after treatment finishes.

A negative breath test does not exclude all stomach problems; it only says active H. pylori was not detected. A positive test does not mean cancer; it means treatment is indicated.

It is also not true that stomach ulcers are caused only by stress or spicy food. H. pylori and anti-inflammatory painkillers are common causes.