From the Guidelines
The most specific test to detect Helicobacter pylori is the urea breath test (UBT). This non-invasive diagnostic method involves having the patient drink a solution containing labeled carbon (either C-13 or C-14), which H. pylori converts to carbon dioxide if present in the stomach. The patient then breathes into a collection device, and the exhaled breath is analyzed for the labeled carbon dioxide.
Key Points
- The UBT has excellent sensitivity (95-98%) and specificity (95-100%), making it the gold standard for both initial diagnosis and confirmation of eradication after treatment 1.
- For the test to be accurate, patients should avoid antibiotics for 4 weeks and proton pump inhibitors for 2 weeks prior to testing, as these medications can suppress H. pylori and lead to false-negative results.
- Other diagnostic options include stool antigen testing (also highly specific but slightly less sensitive), serologic testing (which cannot distinguish between active and past infection), and invasive methods like endoscopy with biopsy for histology, rapid urease testing, or culture.
- The UBT is preferred because it directly detects active infection with minimal false positives, allowing clinicians to confidently diagnose this bacterial infection that causes gastritis, peptic ulcers, and is associated with gastric cancer.
Considerations
- The 14C-UBT is reported to be unreliable in assessing patients who have had gastric surgery and in patients who have been on proton pump inhibitors or ranitidine 1.
- The 13C-UBT is identical to the 14C-UBT except that 13C is a nonradioactive isotope, making it safer for use in children and pregnant females 1.
From the Research
Diagnostic Tests for H. pylori
- The most specific test to detect H. pylori is a matter of debate, with various studies suggesting different tests as the most accurate [(2,3,4,5,6)].
Comparison of Diagnostic Tests
- The urea breath test (UBT) and stool antigen test (SAT) are considered to be highly accurate for detecting active H. pylori infection [(2,4,5)].
- The sensitivity and specificity of different tests are as follows:
- UBT: sensitivity of 89-92%, specificity of 73-96% [(3,5,6)].
- SAT: sensitivity of 96-97.3%, specificity of 83-99.3% [(4,5)].
- Serology: sensitivity of 50-94%, specificity of 54-61% [(2,6)].
Most Specific Test
- The stool antigen test (SAT) is considered to be the most accurate test for H. pylori diagnosis before eradication, with a sensitivity of 96% and specificity of 83% 5.
- However, the urea breath test (UBT) and SAT have similar specificity, and the choice of test may depend on the individual patient and the clinical setting [(2,3,4)].