Which of the following is a diagnostic test for H. pylori?

• A. Ultrasound
• B. Endoscopy culture
• C. Breath test
• D. X-ray

Answer: (C)

H. pylori infection is diagnosed with tests that detect the presence of the bacteria or its urease activity. The breath test uses labeled urea; if H. pylori is present, the bacterial urease splits the urea into ammonia and labeled carbon dioxide, which appears in the breath. This noninvasive test is highly accurate and is commonly used to establish infection and later confirm eradication after treatment.

Ultrasound and X-ray don’t identify H. pylori themselves; they’re used to look for structural or complication-related issues in the abdomen, not to detect the bacteria. Endoscopy with culture can diagnose H. pylori by directly sampling the stomach lining, but it’s invasive and typically reserved for situations where endoscopy is already indicated or noninvasive tests are inconclusive.