What is the recommended method for testing Helicobacter pylori (H. pylori) in a child?

Testing for H. pylori in Children

The urea breath test (UBT) and stool antigen test (SAT) are the recommended non-invasive methods for diagnosing H. pylori infection in children, with UBT being the preferred first-line test due to its higher sensitivity and specificity. 1, 2

Non-Invasive Testing Options

Urea Breath Test (UBT)

• Sensitivity: 94.7%, Specificity: 95.7% 2
• Advantages:
  • Highly accurate for initial diagnosis
  • Easy to perform
  • No special transport conditions required
  • Can be used to confirm eradication
• Limitations:
  • Requires cessation of PPIs, antibiotics, and bismuth products for 2 weeks prior to testing 1, 2
  • Slightly more expensive than serology
  • May produce false-negative results in 10-40% of cases if patient is on PPIs 1
  • False positives can occur with achlorhydria or non-H. pylori urease-producing organisms 2

Stool Antigen Test (SAT)

• Sensitivity: 88.8-92.1%, Specificity: 87.3-87.6% 2
• Advantages:
  • Good alternative when UBT is not available
  • Can be used for initial diagnosis and confirming eradication
  • Less affected by PPI use than UBT
• Limitations:
  • Requires stool sample (potential patient aversion)
  • Requires cessation of PPIs, antibiotics, and bismuth for 2 weeks prior to testing 1
  • Slightly lower accuracy than UBT

Serology (IgG antibody testing)

• Advantages:
  • Not affected by recent use of PPIs, antibiotics, or bismuth 1
  • Inexpensive and widely available
• Limitations:
  • Cannot differentiate between active and past infection 2
  • Cannot be used to confirm eradication 2
  • Requires local validation as antigenic properties of bacterial strains may differ 1
  • Only recommended in high pretest probability situations 2

When to Use Invasive Testing

Endoscopy with biopsy-based tests should be considered in children with:

• Age over 45 years (adults) 1
• Presence of alarm symptoms (regardless of age) 1:
  • Anemia
  • Weight loss
  • Dysphagia
  • Palpable mass
  • Malabsorption
  • Bleeding

During endoscopy, the following tests can be performed:

• Rapid urease test
• Histology
• Culture (allows for antimicrobial susceptibility testing)
• PCR-based molecular testing for antibiotic resistance 1

Testing Algorithm for Children

1. Initial Assessment:

   • For children without alarm symptoms: Use non-invasive testing
   • For children with alarm symptoms: Refer for endoscopy

2. Non-invasive Testing Approach:

   • First choice: Urea breath test (UBT)
   • Alternative: Stool antigen test (SAT)
   • Serology only if patient has been on recent PPI/antibiotic therapy and testing cannot be delayed

3. Pre-test Preparation:

   • Stop PPIs for 2 weeks before testing 1
   • Stop antibiotics for 2 weeks before testing
   • Stop bismuth products for 2 weeks before testing

4. Post-treatment Testing:

   • Wait at least 4 weeks after completion of eradication therapy 3
   • Use UBT or SAT (not serology) to confirm eradication

Special Considerations for Children

• Family members of patients with proven H. pylori infections should be considered for testing 2
• First-generation immigrants from high-prevalence areas and high-risk ethnic groups should be considered for testing 2
• When using UBT in children, ensure appropriate age-specific protocols are followed
• For very young children who cannot perform the breath test properly, stool antigen testing may be more practical

Common Pitfalls to Avoid

• Using serology to confirm eradication (antibodies remain elevated for months after successful treatment) 1
• Testing while patient is on PPIs, antibiotics, or bismuth (increases false-negative results) 1
• Failing to wait at least 4 weeks after treatment before confirming eradication 3
• Using rapid "office" serological tests, which have disappointing sensitivity and specificity 1
• Relying on IgA or IgM tests, which have low specificity and sensitivity 1

By following this evidence-based approach to testing for H. pylori in children, clinicians can accurately diagnose infection and monitor treatment success while minimizing unnecessary invasive procedures.