What is the best method to diagnose Helicobacter pylori (H. pylori) infection in a patient?

Best Method to Test for H. pylori

The urea breath test (UBT) using 13C-urea is the best non-invasive test to diagnose H. pylori infection, with excellent sensitivity (94.7-97%) and specificity (95-95.7%), and should be your first choice in most clinical scenarios. 1, 2

Primary Testing Algorithm

For Patients Under 50-55 Years Without Alarm Symptoms

• Use the 13C-urea breath test (UBT) as first-line testing with sensitivity of 94-97% and specificity of 95-97.7% 2, 3
• Alternatively, use a laboratory-based monoclonal stool antigen test (SAT) which has equivalent diagnostic accuracy to UBT with sensitivity and specificity of approximately 93% 1, 2
• Both tests detect active infection rather than past exposure, making them ideal for initial diagnosis 1, 2

Critical Medication Washout Requirements

• Stop proton pump inhibitors (PPIs) for at least 2 weeks before testing to avoid 10-40% false-negative rates 1, 2, 4
• Stop antibiotics and bismuth for at least 4 weeks before testing 2, 4
• If stopping PPIs is not possible, validated IgG serology can be used as it is unaffected by these medications 1

When to Use Alternative Tests

Validated IgG Serology (Limited Scenarios Only)

• Use serology only when patients cannot stop PPIs or antibiotics and you need immediate testing 1, 2
• Consider serology in patients with ulcer bleeding, gastric atrophy, intestinal metaplasia, or gastric malignancies where bacterial load may be low and cause false-negative results with other tests 1, 2, 3
• Only use validated commercial ELISA-based IgG tests with >90% accuracy—never use rapid office-based serological tests which have poor accuracy (63-97% sensitivity, 68-92% specificity) 2, 3

Critical Limitation of Serology

• Never use serology to confirm eradication after treatment as IgG antibodies remain elevated for months to years after bacterial clearance 2, 3
• Serology cannot distinguish active infection from past exposure, which is its fundamental flaw 2, 3

For Patients Requiring Endoscopy

Indications for Invasive Testing

• Patients ≥50-55 years with new-onset dyspepsia due to increased malignancy risk 2, 4
• Any patient with alarm symptoms (bleeding, weight loss, dysphagia, palpable mass, anemia) regardless of age 2, 4
• Patients who failed eradication therapy requiring culture and antimicrobial sensitivity testing 2, 4

Invasive Test Options During Endoscopy

• Rapid urease test (RUT) provides quick results but requires stopping PPIs for 2 weeks 1, 2
• Histology allows visualization of bacteria and mucosal damage; requires at least two biopsy samples from antrum and body 2, 4
• Culture with susceptibility testing provides definitive proof and resistance patterns, particularly valuable in high clarithromycin resistance areas (>15-20%) 2, 4

Confirmation of Eradication Testing

• Use UBT or laboratory-based monoclonal stool antigen test at least 4 weeks after completing treatment 1, 2, 4
• UBT has sensitivity of 91.6% and specificity of 98.4% for post-treatment confirmation 2
• Never use serology for confirmation as antibodies persist after eradication 2, 3

Common Pitfalls to Avoid

• Avoid rapid in-office stool tests which have significantly lower accuracy than laboratory-based monoclonal tests 1, 2
• Avoid rapid office-based serological blood tests which perform poorly with sensitivities of 63-97% and specificities of 68-92% 3
• Do not test patients currently taking PPIs without either stopping them for 2 weeks or switching to validated IgG serology 1, 2
• Do not use panels of IgG, IgA, and IgM tests as they provide no added benefit over validated IgG tests alone 2

Special Population Considerations

• In children and pregnant women, use 13C-UBT (avoid radioactive 14C-UBT) or stool antigen test as both are safe 2
• In regions with high gastric cancer prevalence, consider endoscopy in H. pylori-positive patients 2