When should we test a patient with symptoms of gastrointestinal distress, such as abdominal pain, bloating, or dyspepsia, particularly those with a history of peptic ulcer disease or gastric cancer, for H. pylori infection?

When to Test for H. pylori Infection

For patients under 50 years old with dyspepsia but without alarm symptoms (bleeding, weight loss, dysphagia, anemia, palpable mass), non-invasive H. pylori testing should be performed first using either the 13C-urea breath test or laboratory-based monoclonal stool antigen test, both with 93-98% accuracy. 1

Age-Based Testing Algorithm

Patients Under 45-50 Years Without Alarm Symptoms

• Test non-invasively first using either 13C-urea breath test (sensitivity 98.1%, specificity 95.1%) or laboratory-based monoclonal stool antigen test (sensitivity 93.2%, specificity 93.2%) 1, 2
• This "test and treat" strategy reduces unnecessary endoscopies by 62% while maintaining equivalent safety and symptom resolution 1, 2
• If H. pylori positive, initiate eradication therapy immediately without requiring endoscopy 1

Patients Over 45-50 Years or Any Age With Alarm Symptoms

• Proceed directly to endoscopy rather than non-invasive testing 3, 2
• Alarm symptoms requiring immediate endoscopy include: bleeding, weight loss, dysphagia, palpable mass, anemia, or malabsorption 3, 2
• The standardized incidence of gastric cancer increases significantly after age 45 (19 per 100,000 for men, 9 per 100,000 for women in Europe) 3

Specific Clinical Indications for Testing

Strongly Recommended Testing Scenarios

• Active peptic ulcer disease (gastric or duodenal ulcers) 2
• History of peptic ulcer disease, especially with complications such as bleeding 2
• Gastric MALT lymphoma 2
• Patients requiring long-term PPI therapy (>1 year) due to increased risk of atrophic gastritis 2
• Atrophic gastritis or intestinal metaplasia (high-risk conditions for gastric cancer) 2

Additional Testing Considerations

• Family history of gastric cancer warrants testing even in younger patients 3
• Patients starting long-term NSAID therapy benefit from H. pylori eradication to prevent peptic ulcer disease 4

Critical Medication Washout Requirements

Testing accuracy depends heavily on proper medication washout to avoid 10-40% false-negative rates:

• Stop proton pump inhibitors for at least 2 weeks before testing with breath test, stool antigen test, rapid urease test, histology, or culture 1, 2
• Stop antibiotics and bismuth for at least 4 weeks before testing 1, 2
• Histamine-2 receptor antagonists do not affect bacterial load and can substitute for PPIs when acid suppression is needed before testing 2

Recommended Testing Methods

First-Line Non-Invasive Tests

• 13C-urea breath test: 98.1% sensitivity, 95.1% specificity; safe for all populations including children and pregnant women 1
• Laboratory-based monoclonal stool antigen test: 93.2% sensitivity and specificity; detects active infection only 1, 2

Tests to Avoid

• Do not use serology as primary diagnostic method—average accuracy only 78%, cannot distinguish active infection from past exposure, and antibodies persist long after eradication 3, 2
• Avoid rapid in-office serological tests—disappointing accuracy with sensitivities 63-97% and specificities 68-92% 3, 2

When Serology May Be Acceptable

• Recent antibiotic or PPI use when other tests would be falsely negative and clinical suspicion remains high 2
• Gastric atrophy, gastric malignancies, or ulcer bleeding where bacterial load may be low 2
• Large epidemiological surveys in high-prevalence areas 2

Post-Treatment Confirmation Testing

Timing and Methods

• Test at least 4 weeks after completing eradication therapy using urea breath test or stool antigen test (sensitivity 91.6%, specificity 98.4%) 1, 5
• In bleeding peptic ulcers, delay testing to 4-8 weeks after the bleeding episode 5
• Never use serology for confirmation—antibodies remain elevated after H. pylori elimination 1, 5

When Confirmation is Mandatory

• Complicated peptic ulcer disease 2
• Gastric ulcer cases (require endoscopic follow-up to ensure complete healing) 5
• Low-grade gastric MALT lymphoma 2
• After treatment failure before initiating second-line therapy 5

Common Pitfalls to Avoid

• Testing too early after treatment (before 4 weeks) yields unreliable false-negative results 5
• Failing to stop PPIs causes 10-40% false-negative rates in all tests except serology 2
• Using serology for post-treatment confirmation—it cannot detect eradication success 2, 5
• Repeating the same failed regimen—after treatment failure, use a completely different antibiotic combination avoiding previously used antibiotics 5

Cost-Effectiveness Considerations

The test-and-treat strategy costs £205.67 per patient per year compared to £404.31 for immediate endoscopy, making it both clinically effective and economically superior in younger patients without alarm features 1. Despite higher individual test costs for breath and stool tests compared to serology, their improved accuracy makes them cost-effective by avoiding unnecessary treatments and complications 3, 1.