H. pylori infections can be diagnosed with blood, breath, and stool tests.
Blood tests can reveal the presence of H. pylori-specific antibodies, which indicate an infection. Urea breath tests can diagnose an H. pylori infection based on abnormally-high carbon dioxide levels. Stool samples can be tested for H. pylori antigens or elevated levels of H. pylori, but the mere presence of H. pylori in the stool doesn’t confirm an active infection.
If these tests don’t provide enough information for a diagnosis, an endoscopy may also be performed to collect images and samples of the esophagus, stomach, and part of the small intestine to check for inflammation and ulcers.[1]