Which test is commonly used to diagnose Helicobacter pylori infection?

• A. Urea breath test
• B. Complete blood count
• C. Abdominal ultrasound
• D. Skin test

Answer: (A)

Diagnosing H. pylori relies on tests that identify active infection in the stomach. The urea breath test is the most commonly used noninvasive option because it detects the bacterium’s urease activity. When the patient ingests labeled urea, H. pylori’s urease breaks it down and releases labeled CO2, which is measured in the breath. A positive result indicates active infection and the test can also confirm eradication after treatment. This method distinguishes current infection from past exposure, unlike antibody-based tests which only show prior contact with the bacteria.

The other options don’t serve this purpose: a complete blood count looks for systemic effects like anemia but doesn’t diagnose H. pylori; an abdominal ultrasound assesses anatomy and is not sensitive for gastric infection; a skin test isn’t used to detect H. pylori.