The test for H. pylori must be performed on an empty stomach, and it is recommended that the test be performed on an empty stomach for 6-8 hours, which is the most accurate. If there is too much food in the stomach, it will affect the absorption of the urea capsule for the carbon 13 or carbon 14 test, and the results of the test will not be accurate. Because the most commonly used method of H. pylori detection is the carbon 13 or carbon 14 breath test, the principle of the test is to use carbon 13 or carbon 14 isotopically labeled urea capsules after oral administration, if there is H. pylori inside the stomach, urease will hydrolyze the urea to produce carbon 13 or carbon 14 labeled carbon dioxide, and then expelled from the stomach, by collecting the amount of carbon dioxide to determine whether the body contains urease The amount of carbon dioxide collected and tested to determine the presence of urease in the body will also clarify the presence of H. pylori infection. If the patient has a large amount of chyme in the stomach, it will affect the test results, so the test must be done on an empty stomach and come to the hospital for the H. pylori carbon 13 or carbon 14 test.