From the Guidelines
The best test for diagnosing H. pylori infection is the urea breath test, which offers high accuracy with sensitivity and specificity exceeding 95%. This non-invasive test involves the patient drinking a solution containing labeled carbon urea, which H. pylori converts to carbon dioxide that can be detected in exhaled breath 1. Other reliable options include the stool antigen test, which directly detects H. pylori proteins in stool samples with similar accuracy to the breath test. For patients undergoing endoscopy, biopsy-based tests like rapid urease testing, histology, or culture can provide definitive diagnosis.
Key Considerations
- Serological blood tests can detect antibodies but cannot distinguish between current and past infections, making them less useful for confirming active infection or documenting eradication 1.
- Proton pump inhibitors, bismuth compounds, and antibiotics can interfere with test accuracy, so these medications should be discontinued at least 2 weeks before testing (4 weeks for antibiotics) to avoid false-negative results 1.
- The choice of test should consider factors like cost, availability, patient factors, and whether the patient requires endoscopy for other reasons.
Test Characteristics
- Urea breath test: sensitivity and specificity exceeding 95% 1.
- Stool antigen test: sensitivity of 94% and specificity of 92% 1.
- Rapid urease test: sensitivity ranges from 80 to 95% and specificity ranges from 95–100% 1.
Clinical Context
- In cases of bleeding peptic ulcer, H. pylori testing on endoscopic tissue biopsy may be available 1.
- For patients with a high pretest probability of H. pylori-related disease, serology may be used, but confirmation with a urea breath test, stool antigen test, or endoscopy is recommended before starting treatment 1.
From the Research
Diagnostic Methods for H. Pylori Infection
The diagnosis of H. Pylori infection can be achieved through various methods, including:
- Invasive methods: requiring gastric biopsies performed during endoscopy, such as histology, culture, rapid urease test, and PCR 2
- Non-invasive methods: serology, 13C urea breath test, and stool antigen test 2, 3, 4
Comparison of Diagnostic Methods
Studies have compared the accuracy of different diagnostic methods, including:
- The 13C urea breath test, which is considered the most accurate method in patients irrespective of age 2
- The stool antigen test, which has diagnostic performances approaching those of the urea breath test 2
- The rapid urease test, which is less sensitive but specific, and can be done by the gastroenterologist himself 2
- Serological tests, which are widely available and cheap, but may not be appropriate for determining the underlying disease associated with H. pylori infection 2
Non-Invasive Tests
Non-invasive tests can be categorized into:
- Active tests: detect active infection, such as the urea breath test and the stool antigen test 3, 4
- Passive tests: markers of exposure to H. pylori, but do not indicate if active infection is ongoing, such as serology 3, 4
Recommendations for Testing and Treatment
Recommendations for testing and treatment of H. Pylori infection include:
- Stopping proton pump inhibitor therapy for 1-2 weeks prior to testing if possible 5
- Using the urea breath test to rule out a false-negative biopsy test result in the setting of bleeding peptic ulcer disease 5
- Testing for H. Pylori in patients with active and past ulcer disease, and gastric-mucosa associated lymphoid tissue lymphoma 5