Which noninvasive test is commonly used to diagnose H. pylori infection in adults?

• A. Urea breath test
• B. Complete blood count
• C. Stool antigen test
• D. Abdominal MRI

Answer: (C)

Noninvasive testing for H. pylori focuses on detecting the current infection without performing endoscopy. The stool antigen test looks for H. pylori components shed in the stool, so a positive result indicates active infection and a negative result suggests no infection, assuming any recent antibiotics or acid-suppressing medicines have been managed appropriately. It’s a practical and comfortable option for adults because it doesn’t require special equipment, fasting, or invasive procedures, and it can be used both to diagnose infection and to confirm eradication after treatment. While other noninvasive tests like the urea breath test are also highly accurate, the stool antigen test is commonly used in many settings for its convenience and reliability in detecting active infection. Tests like a complete blood count or MRI don’t diagnose H. pylori; CBC may show related effects like anemia, and MRI is an imaging study for anatomy, not infection status.