What is being tested?
These tests are looking for evidence of an infection in your gastrointestinal tract by a bacterium, known as Helicobacter pylori. This bacterium is known to be a major cause of peptic ulcer disease. H. pylori is also associated with the development of gastric (stomach) cancer.

How is the sample collected for testing?
The sample collected depends on the test your doctor orders. It may be as simple as submitting a stool sample to look for the H. pylori antigen or a blood sample drawn from a vein in your arm to detect antibody to the bacteria.

A more invasive test will require a procedure called an endoscopy, which means putting a tube down the throat into the stomach to take a small piece of tissue (a biopsy) from the stomach lining. A biopsy can be used to detect other reasons for stomach pain, as well as be cultured or tested in the laboratory for H. pylori. H. pylori produces urease, a special enzyme that allows it to survive in the acidic environment of the stomach. The lab can detect the presence of this bacterium by looking for this enzyme in the tissue sample. The tissue may also be examined under a microscope by a pathologist, who will look for these bacteria or any other signs of disease that may explain your symptoms.

Sometimes a breath test can be used instead of a biopsy. You will be asked to drink a special liquid containing a low level of radioactive material that is harmless. If H. pylori is present in your GI tract, the material will be broken down into radioactively-labeled carbon dioxide gas. By testing the expelled air collected from your breath sample, the laboratory can determine if this organism is in your body.

Is any test preparation needed to ensure the quality of the sample?
No special preparation is needed for the blood test.

For the breath test, you may be instructed to refrain from certain medications:

Four weeks before the test, do not take any antibiotics or Pepto Bismol (oral bismuth subsalicylate).

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 tissue biopsy, you may be asked to refrain from taking any antibiotics, antacids, or bismuth treatments for 14 days prior to the test.

If undergoing endoscopy, you may be instructed to fast after midnight the night prior to the procedure.