What is the recommended diagnostic and treatment approach for a patient presenting with symptoms suggestive of H pylori infection, taking into account their medical history and potential previous treatments or allergies?

H. pylori IgM Antibody Testing

IgM antibody testing for H. pylori should not be used in clinical practice—these tests are not FDA-approved, have poor sensitivity and specificity, and provide no diagnostic value over validated IgG serology tests. 1

Why IgM Testing is Not Recommended

• IgA and IgM anti-H. pylori tests are generally not approved by the US Food and Drug Administration (FDA) and are not recommended or trusted because of their low specificity and sensitivity 1
• Panels of IgG, IgA, and IgM tests provide no added benefit over IgG tests alone and generally consist of non-FDA-approved tests of unclear diagnostic value 1, 2
• When using large commercial laboratories in the United States, it is critical to request only FDA-approved tests, as commercial laboratories often offer and preferentially use in-house derived tests of unknown specificity and sensitivity 1

Recommended Diagnostic Approach Instead

For initial diagnosis in patients under 50 years without alarm symptoms (bleeding, weight loss, dysphagia), use the urea breath test (13C-UBT) or laboratory-based monoclonal stool antigen test as first-line diagnostic methods. 2, 3

Non-Invasive Testing Algorithm

• First-line options: 13C-urea breath test (sensitivity 94-97%, specificity 95-97.7%) or laboratory-based monoclonal stool antigen test (sensitivity 93.2%, specificity 93.2%) 2, 4
• Critical medication washout: Stop proton pump inhibitors for at least 2 weeks and antibiotics/bismuth for at least 4 weeks before testing to avoid false-negative results 1, 2
• Limited role for IgG serology: Validated IgG serology (not IgM) may only be considered when patients have recently used antibiotics or PPIs and cannot wait for the washout period, or in cases of ulcer bleeding, atrophic gastritis, or gastric malignancies where other tests may be falsely negative 2

When to Use Endoscopy with Invasive Testing

• Patients ≥50 years with new-onset dyspepsia require endoscopy due to increased malignancy risk 2
• Any patient with alarm symptoms (bleeding, weight loss, dysphagia, palpable mass, anemia) regardless of age should undergo endoscopy first 2
• Patients who have failed eradication therapy need endoscopy with culture and antimicrobial sensitivity testing to guide subsequent treatment 2

Common Pitfalls to Avoid

• Never use rapid in-office serological tests (including IgM tests)—they have limited accuracy and should be avoided entirely 2
• Do not use serology to confirm eradication after treatment, as antibodies remain elevated long after H. pylori elimination (serologic "scar") 1, 2
• Avoid testing during or shortly after PPI use—PPIs cause 10-40% false-negative rates by reducing bacterial load 2
• Do not rely on serology alone even when using validated IgG tests—confirm active infection with UBT or stool antigen test before starting treatment unless there is very high pretest probability (such as active duodenal ulcer) 1

Confirmation of Eradication

• Test at least 4 weeks after completing eradication therapy using UBT or stool antigen test (not serology) 2
• Ensure proper medication washout: off PPIs for ≥2 weeks, off antibiotics/bismuth for ≥4 weeks 2