There are two basic ways that an H. pylori infection can be diagnosed: either by passing a fiberoptic tube down the esophagus and into the stomach (called an EGD, or esophagogastroduodenoscopy) or by doing noninvasive tests.

The EGD involves using a small flexible endoscope, which is introduced through the mouth and advanced through the pharynx, esophagus, stomach, and duodenum. It is performed by a gastroenterologist and requires light anesthesia.

Noninvasive testing can involve a stool antibody test, blood antibody test, or a breath test. The fastest is a breath test, which has a high specificity and sensitivity rating. It entails merely drinking a mixture and then blowing into a small bag.

The breath test measures a gas released by the H. pylori bacteria in large amounts. The results come back the next day.

The breath test can also be used after treatment to see if the organism has been eradicated.