Diagnosis

Several tests and procedures are used to determine whether you have an H. pylori infection. Testing is important for detection of H. pylori but also to test after treatment to be sure it has been eliminated.

• Stool tests. The most common stool test to detect H. pylori is called a stool antigen test that looks for foreign proteins (antigens) associated with H. pylori infection in your stool. Antibiotics, acid-suppressing drugs known as proton pump inhibitors (PPIs) and bismuth subsalicylate (Pepto-Bismol) can interfere with the accuracy of these tests. If you were previously diagnosed with and treated for H. pylori, your doctor will generally wait at least four weeks after you complete your antibiotic treatment to test your stool. If you are taking a PPI, your doctor will ask you to stop taking PPI medications for one or two weeks before the test. This test is available for adults and children older than 3.

  A laboratory test called a stool polymerase chain reaction (PCR) test can detect H. pylori infection in your stool and mutations that may be resistant to antibiotics used to treat it. This test is more expensive and may not be available at all medical centers. This test is available for adults and children.

• Breath test. During a breath test, you swallow a pill, liquid or pudding that contains tagged carbon molecules. If you have an H. pylori infection, carbon is released when the solution is broken down in your stomach.

  Your body absorbs the carbon and expels it when you exhale. You exhale into a bag, and your doctor uses a special device to detect the carbon molecules.

  As with stool tests, PPIs, bismuth subsalicylate (Pepto-Bismol) and antibiotics can interfere with the accuracy of this test. If you are taking a PPI, your doctor will ask you to stop taking the PPI medications for one or two weeks before the test. If you were previously diagnosed with and treated for H. pylori, your doctor will generally wait at least four weeks after you complete your antibiotic treatment to perform the breath test. This test is available for adults and children.

• Scope test. You'll be sedated for this test, known as an upper endoscopy exam. During the exam, your doctor threads a long flexible tube equipped with a tiny camera (endoscope) down your throat and esophagus and into your stomach and duodenum. This instrument allows your doctor to view any irregularities in your upper digestive tract and remove tissue samples (biopsy). These samples are analyzed for H. pylori infection.

  This test is done to investigate symptoms that may be caused by other conditions such as gastric ulcer or gastritis that may be due to H. pylori. The test may be repeated after treatment depending on what is found at the first endoscopy or if symptoms persist after H. pylori treatment. At this second exam, biopsies can be performed to make sure H. pylori has been eliminated. If you were previously diagnosed with and treated for H. pylori, your doctor will generally wait at least four weeks after you complete your antibiotic treatment to perform the breath test. If you are taking a PPI, your doctor will ask you to stop taking the PPI medications for one or two weeks before the test.

  This test isn't always recommended solely to diagnose an H. pylori infection because it's more invasive than a breath or stool test. But it may be used to perform detailed testing for doctors to determine exactly which antibiotic to prescribe to treat H. pylori, especially if antibiotics fail or to rule out other digestive conditions.