Urita Y et al. (2004) Breath sample collection through the nostril reduces false-positive results of 13C-urea breath test for the diagnosis of Helicobacter pylori infection. Dig Liver Dis 36: 661–665

The 13C-urea breath test (UBT) is widely used in the diagnosis of H. pylori infection. False-positive results can be generated, however, by other urease-producing bacteria in the mouth and intestine. Several methods have been devised to avoid this problem, including the endoscopic UBT, in which 13C-urea solution is sprayed directly into the stomach. Although this approach is more reliable, it is invasive and relatively inconvenient. Urita and colleagues have recently described a non-invasive modification, based on breath sample collection through the nostril.

The authors analyzed data from 127 patients, of whom 42 had biopsy-confirmed H. pylori infection. Within 1 week of endoscopy, the patients were subjected to both the standard and the modified UBT. Breath samples were collected through the mouth or the nostril for the two tests, respectively, at baseline and at 1, 3, 5, 10, 15, 20 and 30 minutes after administration of the 13C-urea solution.

The modified test was able to differentiate between H. pylori-positive and H. pylori-negative patients at the 1 minute time point, whereas the standard test did not show significant differences until 3 minutes had elapsed. Additionally, the modified test reached 100% sensitivity and specificity at 20 minutes with a 2.5% cut-off, whereas the optimal values at any time point for the standard test were 97.7% and 94.2%, respectively.

In conclusion, the modified test represents an easy, non-invasive means of avoiding false-positive results in H. pylori detection.