What is Helicobacter pylori (H. pylori) Antigen - Stool?
Helicobacter pylori is a type of bacteria that is known to be a major cause of peptic ulcers. H. pylori testing detects an infection of the digestive tract caused by the bacteria to help diagnose the cause of symptoms and/or ulcers.
H. pylori infections of the digestive tract are very common, with as many as half of the world’s population infected. However, most people with H. pylori never have any symptoms. Still, H. pylori infection increases the risk of developing ulcers (peptic ulcer disease), persistent stomach inflammation (gastritis), and gastric (stomach) cancer. The bacteria decrease the stomach’s ability to produce mucus, making the stomach prone to damage from digestive acid and peptic ulcers.
A few different types of H. pylori testing are available, such as a stool antigen test and a breath test. Some are less invasive than others. See the “How is the test used?” section under Common Questions for details.
How is the sample collected for testing?
The sample collected depends on the test ordered:
- For the urea breath test, a healthcare professional collects an initial sample of your breath by having you breathe into a bag. You are given a liquid to drink containing a substance called urea. Another breath sample is collected after a specific amount of time has elapsed.
- For the stool antigen test, a stool sample is collected in a clean container.
A more invasive test will require a procedure called an endoscopy, which involves putting a thin tube with a tiny camera on the end down the throat into the stomach. This allows your healthcare practitioner to view the stomach lining and take a small piece of tissue (a biopsy) from the lining for examination.
Is any test preparation needed to ensure the quality of the sample?
For the breath test, you may be instructed to refrain from taking certain medications:
- Four weeks before the test, do not take any antibiotics or oral bismuth subsalicylate (Pepto Bismol®).
- Two weeks before the test, do not take any prescription or over-the-counter proton pump inhibitors, such as omeprazole, lansoprazole, or esomeprazole.
- One hour before the test, do not eat or drink anything (including water).
If submitting a stool sample or having a tissue biopsy collected, it may be necessary to refrain from taking any antibiotics, antacids, or bismuth treatments for 14 days prior to the test.
If undergoing endoscopy, fasting, usually overnight, may be required. Only water may be permitted.