How soon can a patient who has just completed a 2-week course of Helicobacter pylori (H. pylori) therapy for dyspepsia undergo a test to confirm eradication after stopping the therapy?

Timing of H. pylori Eradication Testing

The test to confirm H. pylori eradication should be performed at least 4 weeks after completion of therapy, making option A (in 4 weeks) the correct answer. 1, 2

Rationale for the 4-Week Waiting Period

The gastric mucosa requires at least 4 weeks to recover after H. pylori treatment, and testing before this period yields unreliable false-negative results. 2 This occurs because:

• Temporary bacterial suppression rather than true eradication can occur immediately after treatment, leading to false-negative results if testing is performed too early. 2
• The bacterial load decreases temporarily during and immediately after treatment, but viable organisms may still be present and will repopulate if eradication was unsuccessful. 3
• Testing at 1 week (option C), 2 weeks (option B), or immediately (option D) will produce unacceptably high rates of false-negative results. 1

Guideline Consensus

Multiple international guidelines consistently recommend the same 4-week minimum interval:

• The European Helicobacter Study Group (Maastricht Consensus) explicitly states that follow-up tests should be performed "no earlier than four weeks after cessation of treatment." 1
• The American Gastroenterological Association recommends testing "at least 4 weeks after completion of H. pylori treatment." 2
• The American College of Gastroenterology confirms that testing before 4 weeks may show false-negative results as the gastric mucosa needs time to recover from treatment effects. 2

Recommended Testing Methods at 4 Weeks

When performing the test of cure at 4 weeks or later:

• Urea breath test (UBT) is the gold standard non-invasive test with sensitivity of 94.7-97% and specificity of 95-100%. 2
• Monoclonal stool antigen test is an equally accurate alternative with sensitivity and specificity >90%. 2
• Serology has no role in determining eradication success, as antibody titers take 6 months to fall and cannot distinguish active infection from past exposure. 2, 4

Pre-Testing Medication Washout Requirements

Before performing the test at 4 weeks:

• Proton pump inhibitors (PPIs) should be withheld for at least 7-14 days before testing. 2
• Antibiotics and bismuth should be withheld for at least 4 weeks. 2
• Patients should fast for at least 6 hours before breath testing. 2

Special Considerations

In cases of bleeding peptic ulcers, an extended waiting period of 4-8 weeks after the bleeding episode may be recommended before performing delayed testing. 2, 4