First, the principle of H. pylori is an important pathogenic factor in acute and chronic gastritis, peptic ulcer, and has a close relationship with the development of gastric cancer. The infection rate of H. pylori in our general population reaches 50%-60%, and the infection rate is higher in some areas. Since H. pylori can produce strong urease, urease can decompose urea to produce ammonia and CO2, the urea that is not decomposed is absorbed and excreted from the urine as a prototype, while the CO2 produced by hydrolysis enters the blood and is excreted from the body through the lungs. When a certain amount of 14C-urea is taken orally, if H. pylori is present in the stomach, the tracer urea is decomposed by the urease produced by H. pylori and the tracer carbon is exhaled as 14CO2 through the lungs. The exhaled gas is collected and the 14CO2 content is measured quantitatively by the instrument, which can determine the presence of H. pylori infection in the stomach. I. Methods (a) Patient preparation: The patient must be off antibiotics and bismuth for 30 days and off proton pump inhibitors with aluminum thioglycollate for two weeks. Fasting for more than 6 hours before the examination. (b) Examination methods: II. Indications 1. Those with gastric discomfort and suspected H. pylori infection. 2. Patients with acute and chronic gastritis and gastric and duodenal ulcers. 3. Evaluation of efficacy and diagnosis of recurrence after H. pylori eradication therapy. 4. Epidemiological investigation and screening means of H. pylori infection. Contraindications There are no obvious contraindications to urea breath test. IV. Judgment of results Urea breath test (14C-UBT) ≥150dpm is positive. V. Clinical application Studies have shown that a variety of gastrointestinal diseases are associated with H. pylori infection, about 90% of duodenal ulcers and 70% of gastric ulcers have H. pylori infection, and others such as acute and chronic gastritis, gastroesophageal reflux, functional dyspepsia, etc. are also very closely related to H. pylori infection. Urea breath test is mainly used for the diagnosis of H. pylori infection, especially for the clinical review and evaluation of the effect of HP infection treatment, the determination of whether HP is eradicated, as well as the follow-up of HP infection treatment for recurrence, to decide whether further treatment is needed. Its sensitivity is 90%-97% and specificity is 89%-100%. The method is also suitable for large-scale screening and epidemiological studies. Urea breath test is a simple, inexpensive, non-invasive, painless, accurate, safe and reliable, sensitive and reliable patient-friendly method to diagnose the presence or absence of H. pylori infection. Quality control The following factors can lead to false negatives and should be avoided 1. The subject has used HP inhibiting drugs in the last month, such as antibiotics, bismuth, and has taken aluminum thioglycollate in the last two weeks. 2. The subject has had upper gastrointestinal bleeding within the last week. 3. The subject has food in the stomach, and it is difficult for the oral 14C-urea capsule to come into contact with the gastric mucosa. The following factors can lead to false positives and should be avoided The subject has undergone partial gastrectomy and may have a lack of gastric acid and be infected by bacteria containing urease in the mouth resulting in a false positive.