Diagnosis of Helicobacter pylori Infection
For diagnosing H. pylori infection, use the urea breath test (UBT) or stool antigen test as first-line non-invasive diagnostic methods, with UBT being the most accurate option demonstrating 94-97% sensitivity and 95% specificity. 1
Primary Diagnostic Approach
Non-Invasive Testing (Preferred Initial Strategy)
Urea Breath Test (UBT) is the most accurate non-invasive diagnostic test available:
- Achieves sensitivity of 94-97% and specificity of 95%, making it superior to other non-invasive methods 1, 2
- Detects active infection by measuring urease activity of H. pylori in the stomach 2
- Requires patients to fast for at least 6 hours before testing for optimal accuracy 1, 2
- Can be performed using either 13C (non-radioactive, preferred for children and pregnant women) or 14C isotopes 3
Stool Antigen Test serves as an excellent alternative:
- Demonstrates sensitivity and specificity of approximately 93%, comparable to UBT 1, 4
- Directly detects H. pylori bacterial antigens in stool specimens, confirming active infection 4
- The American College of Gastroenterology specifically recommends using a laboratory-based validated monoclonal stool antigen test 1
- More practical than invasive methods while avoiding endoscopy-related discomfort and complications 4
When to Use Invasive Testing
Invasive diagnostic methods require endoscopy and are indicated when:
- Patients are over 45-55 years of age with dyspeptic symptoms 5
- Alarm symptoms are present (anemia, weight loss, dysphagia, melena, palpable mass) 5, 2
- Treatment failure has occurred and antimicrobial resistance is suspected 1
Histological examination is the gold standard among invasive tests:
- Requires at least two biopsy samples from both antrum and body for improved sensitivity 1
- Immunohistochemistry provides the highest sensitivity and specificity among histological methods 1
Rapid Urease Test (RUT) offers quick results:
- Pre-treatment sensitivity ranges from 80-95% with specificity of 95-100% 1
- Requires approximately 10^4 organisms for a positive result 1
Culture provides definitive proof:
- Allows for antimicrobial susceptibility testing, particularly valuable after treatment failure 1
- Technically demanding with variable sensitivity between laboratories 1
Critical Testing Considerations
Medication Interference (Common Pitfall)
All tests can produce false-negative results if patients have recently used:
- Proton pump inhibitors: discontinue at least 2 weeks before testing 1, 4
- Antibiotics: discontinue at least 4 weeks before testing 1
- Bismuth compounds: discontinue before testing 1, 4
Tests to Avoid
Serological tests are NOT recommended for diagnosing active infection:
- Cannot distinguish between active infection and past exposure 1
- Antibody levels persist in blood long after eradication 1
- Overall accuracy of commercial ELISA serology tests averages only 78% 1
- The only exception: validated IgG serology may be considered when medication washout is not possible 1
Rapid in-office immunochromatographic stool tests should be avoided:
- Lower accuracy of only 80-81% compared to laboratory-based tests 1
Post-Treatment Confirmation
For confirming eradication after treatment:
- Perform testing no earlier than 4 weeks after completion of treatment 1
- Use UBT or stool antigen test only 1
- Never use serology to confirm eradication, as antibodies persist for months to years 1
Clinical Algorithm for Test Selection
Young patients (<45-55 years) without alarm symptoms:
- Use "test and treat" strategy with UBT or stool antigen test 5, 1, 2
- This approach reduces endoscopy needs by 62% and costs significantly less (£205.67 vs £404.31 per patient per year) 5
Patients >45-55 years or with alarm symptoms:
- Refer for endoscopy with biopsy-based testing 5
Post-treatment evaluation:
- UBT or stool antigen test at least 4 weeks after treatment completion 1
Treatment failure cases:
- Consider culture for antimicrobial susceptibility testing 1