What is the recommended method for diagnosing H. pylori (Helicobacter pylori) infection?

H. pylori Diagnosis

Recommended Diagnostic Approach

For initial diagnosis of H. pylori infection, use the urea breath test (UBT) or laboratory-based monoclonal stool antigen test as first-line non-invasive methods, with UBT demonstrating sensitivity of 94-97% and specificity of 95%, and stool antigen test showing comparable accuracy at approximately 93% for both sensitivity and specificity. 1, 2

Algorithm for Test Selection

For Patients NOT Requiring Endoscopy

Young patients (<50 years) with dyspepsia and no alarm symptoms:

• First choice: UBT or laboratory-based monoclonal stool antigen test 1, 3
• Both tests detect active infection only, unlike serology which cannot distinguish current from past infection 2
• UBT is considered the most accurate non-invasive test, measuring urease activity to detect active infection 1, 3
• Stool antigen test directly detects bacterial antigens with comparable accuracy to UBT 1, 2

Critical medication washout periods before testing:

• Stop proton pump inhibitors (PPIs) for at least 2 weeks before testing 1, 2
• Discontinue antibiotics for at least 4 weeks before testing 1, 3
• Failure to observe these washout periods leads to false-negative results in all tests except serology 1, 2

For Patients Requiring Endoscopy

Mandatory endoscopy with invasive testing for:

• Age ≥50 years with new-onset dyspepsia (increased malignancy risk) 1, 2
• Alarm symptoms: bleeding, weight loss, dysphagia, palpable mass, or malabsorption 1, 2
• Failed eradication therapy requiring culture and antimicrobial susceptibility testing 1, 2

Invasive test options during endoscopy:

• Rapid urease test (RUT): Sensitivity 80-95%, specificity 95-100%, provides quick results 1, 3
• Histology: Requires at least two biopsy samples from antrum and body for improved sensitivity; immunohistochemistry is the gold standard for histological diagnosis 1, 3
• Culture: Provides definitive proof and allows antimicrobial susceptibility testing, particularly valuable after treatment failure 1, 3

Tests to AVOID

Serology testing should NOT be used for routine diagnosis:

• Cannot distinguish between active infection and past exposure 2, 3
• Overall accuracy of commercial ELISA serology tests averages only 78% (range 68-82%) 2, 3
• Antibody levels persist for months to years after eradication 2, 3
• Never use serology to confirm eradication 1, 2

Rapid in-office immunochromatographic tests should be avoided:

• Significantly lower accuracy (80-81%) compared to laboratory-based monoclonal tests 3
• Only laboratory-based monoclonal antibody stool tests achieve high accuracy 2

Confirmation of Eradication

Testing protocol after treatment:

• Perform testing no earlier than 4 weeks after completion of treatment 1, 2
• Use only UBT or stool antigen test for confirmation—never serology 1, 2
• Ensure proper medication washout (PPIs for 2 weeks, antibiotics for 4 weeks) 1, 2

Special Circumstances Where Serology May Be Considered

Limited situations where serology has utility:

• Recent use of antibiotics or PPIs when washout is not possible and clinical suspicion remains high 2, 3
• Gastric atrophy, gastric malignancies, or ulcer bleeding where other tests may be falsely negative due to low bacterial load 2
• Large epidemiologic surveys and population screening in high-prevalence areas 2

Common Pitfalls to Avoid

• Testing patients currently on PPIs or recent antibiotics leads to false-negative results in UBT, stool antigen test, RUT, histology, and culture 1, 2
• Using serology for active infection diagnosis or eradication confirmation results in unreliable results due to persistent antibodies 2, 3
• Inadequate biopsy sampling during endoscopy (need at least two samples from antrum and body) reduces histology sensitivity 1, 3
• Using rapid in-office tests instead of laboratory-based monoclonal stool tests significantly reduces diagnostic accuracy 2, 3