Best Test for H. pylori: Breath vs. Stool
Both the urea breath test (UBT) and the stool antigen test (SAT) are equivalent in diagnostic accuracy when a validated laboratory-based monoclonal stool test is used, with the UBT remaining the gold standard but the SAT offering a practical alternative with comparable performance. 1
Diagnostic Accuracy Comparison
Urea Breath Test (UBT)
- The UBT has the highest accuracy with sensitivity of 88-95% and specificity of 95-100% 2
- Remains the best test to diagnose H. pylori infection and is easy to perform 1
- Considered the gold standard for both initial diagnosis and post-treatment confirmation 3
Stool Antigen Test (SAT)
- Laboratory-based monoclonal SATs have equivalent accuracy to UBT for both initial and post-treatment diagnosis 1
- Meta-analysis of 22 studies including 2,499 patients demonstrated high accuracy when monoclonal antibodies are used 1
- Sensitivity and specificity exceed 90% when validated laboratory-based monoclonal tests are employed 1, 2
Critical Distinction: Test Format Matters
You must use laboratory-based ELISA format with monoclonal antibodies—rapid in-office stool tests have limited accuracy and should be avoided. 1
- Rapid in-office tests show disappointing accuracy (sensitivity 63-97%, specificity 68-92%) 2
- Only validated laboratory-based monoclonal tests achieve the high performance comparable to UBT 1
Practical Considerations for Test Selection
When to Prefer UBT
- Patient preference strongly favors breath testing over stool collection 1
- Suspected false positive results requiring confirmation (e.g., in patients with achlorhydria or atrophic gastritis who may have urease-producing non-H. pylori organisms) 1
- When insurance coverage is equivalent between tests 1
When to Prefer SAT
- Patients who must continue PPI therapy, as stool testing may be more practical in clinical workflow 3
- Cost considerations in settings where breath test equipment and maintenance are prohibitively expensive 1
- When confirming suspected false positive UBT results before initiating additional therapy 1
Essential Pre-Test Requirements (Both Tests)
Both tests require identical medication washout periods to avoid false negative results:
- Discontinue antibiotics and bismuth for at least 4 weeks 1, 2
- Discontinue PPIs for at least 7-14 days (minimum 2 weeks preferred) 1, 2, 3
- Ensure 6-hour fasting before testing 2
- H2-receptor antagonists do not affect bacterial load and can substitute for PPIs during the washout period 1
Common Pitfalls to Avoid
False negative results occur when testing too soon after medications that reduce bacterial load—a positive result can be trusted, but negative results require proper medication washout 1
False positive UBTs can occur in achlorhydria (pernicious anemia, atrophic gastritis) due to urease-producing non-H. pylori organisms—confirm with SAT or endoscopy before retreatment 1
Never use serology for active infection diagnosis—it cannot distinguish current infection from past exposure and remains positive long after eradication 1, 3
Never use rapid office-based stool tests—their accuracy is insufficient for clinical decision-making 1, 2
Clinical Algorithm for Test Selection
First, exclude serology—only validated IgG serology has limited use in specific scenarios (recent antibiotic/PPI use, bleeding ulcers, atrophy, malignancy) but cannot confirm active infection 1
For initial diagnosis in asymptomatic patients (e.g., family members of infected patients): Choose either UBT or laboratory-based monoclonal SAT based on local availability, cost, and patient preference 2
For post-treatment confirmation: Either UBT or laboratory-based monoclonal SAT at least 4 weeks after treatment completion 3
When UBT shows unexpected positive result (especially in patients with known achlorhydria/atrophy): Confirm with SAT before initiating additional therapy 1
When endoscopy is clinically indicated: Use biopsy-based testing (histology with immunohistochemical staining, rapid urease test, or culture for susceptibility testing) 1