Helicobacter pylori infection can be diagnosed by invasive (that is, endoscopy and biopsy) and non-invasive techniques. The choice of a diagnostic test should depend on the clinical circumstances, the pre-test probability of infection, sensitivity and specificity of the test (or more correctly the likelihood ratio of a positive and negative test), the cost effectiveness of the testing strategy, and the availability of the test. Some clinical circumstances warrant invasive studies: patients who have failed eradication therapy may need culture and antimicrobial sensitivity testing to help determine an appropriate regimen, older patients with new onset dyspepsia, and those with “alarm” symptoms (bleeding, weight loss, etc) that raise the concern of malignancy. Non-invasive studies are preferable in epidemiological studies and in young children. Recent studies have also demonstrated that a strategy to test and treat H pylori in uninvestigated young (<50 years) dyspeptic patients in primary care is safe and reduces the need for endoscopy.1

Until recently, only two non-invasive methods of testing forH pylori have been available: (1) the¹³C or ¹⁴C labelled urea breath test (UBT), which is based on detection of ¹³C or ¹⁴C labelled CO₂ in expired air as a result ofH pylori urease activity2-4and (2) serology (which is based on detection of a specific anti-H pylori IgG antibody in the patient's serum.5 ,6 Several new methods of detectingH pylori have recently been described and include detection of antibodies in saliva7 and urine,8 and detection of antigens in stool.