Helicobacter pylori Antigen (Stool)
This test looks for pieces of the Helicobacter pylori bacterium (its antigens) in a sample of your stool. H. pylori is a common bacterium that can live in the lining of your stomach.
H. pylori is one of the most frequent causes of stomach and upper-intestinal ulcers, and long-term infection is linked to chronic inflammation of the stomach lining. Because the stool antigen test detects the bacterium itself rather than antibodies, it reflects a current, active infection. It is also commonly used to confirm that treatment has successfully cleared the infection.
A positive result means H. pylori antigen was detected, which points to an active infection in your stomach or intestine at the time of the test. Your clinician will interpret this alongside your symptoms and may recommend treatment (usually a combination of antibiotics and acid-reducing medication) and a follow-up test to confirm the infection has cleared.
A negative result means no H. pylori antigen was detected, which suggests you do not have an active infection. Recent use of antibiotics, bismuth, or acid-suppressing medications can lower the accuracy of the test, so your clinician may consider timing when interpreting the result.
The expected, normal result is negative (no antigen detected). If you are being tested to confirm a cure after treatment, your clinician will typically wait at least four weeks after finishing antibiotics, and after stopping acid-reducing medication, so the result is reliable.
Sources
- H. pylori Infection Tests: MedlinePlus Medical Test
- Helicobacter pylori (H. pylori) Infection: Cleveland Clinic
Educational context only, not medical advice or a diagnosis. Reference ranges vary by lab, age and sex; always discuss your results with a clinician.