Which test is used to non-invasively detect Helicobacter pylori infection?

Study for the Medical Council of Canada Qualifying Examination (MCCQE) I. Engage with flashcards and multiple-choice questions with detailed feedback. Prepare confidently!

The test used to detect Helicobacter pylori infection noninvasively directly assesses active infection by exploiting the bacteria’s urease activity. You drink urea labeled with a carbon isotope (13C or 14C). If H. pylori is present in the stomach, its urease enzyme breaks down the urea, releasing labeled CO2 which is absorbed into the bloodstream and exhaled in the breath. Measuring the isotope in the exhaled breath reveals active infection with high accuracy. This approach is preferred because it reflects current bacterial presence rather than past exposure, unlike blood antibody tests that can stay positive long after eradication. Endoscopy with biopsy is invasive, and while stool antigen testing is also noninvasive and useful for active infection or post-treatment monitoring, the urea breath test is widely favored for its strong sensitivity and specificity. Remember that recent use of antibiotics or proton pump inhibitors can affect results, so these should be paused according to guidelines before testing.