Breath sample collection through the nostril reduces false-positive results of 13C-urea breath test for the diagnosis of Helicobacter pylori infection

Background. One of the disadvantages of C-13-urea breath test is possible interference by urease activity not related to Helicobacter pylori. Aims. We design the simple and non-invasive modification to avoid the contamination of (CO2)-C-13 produced in the mouth. Patients and methods. One hundred and twenty-nine patients who underwent diagnostic upper endoscopy were enrolled. Within 1 week of the endoscopic procedure, each patient received the modified C-13-urea breath test. Breath samples were collected at baseline and at 1, 3, 5, 10, 15, 20 and 30 min after ingestion of 100 mg C-13-urea solution through the mouth and the nostril at each time point. Results. The breath Delta(13)CO(2) value through the nostril at 1 min was already higher in H. pylori-positive patients than in H. pylori-negative patients. Using 2.5parts per thousand as the cut-off value, the sensitivity and specificity of the modified C-13-urea breath test at 20 min were both 100%, whereas the sensitivity and specificity of the standard C-13-urea breath test were 97.7 and 94%, respectively, using 3parts per thousand as the cut-off value. Conclusions. The modified C-13-urea breath test in which breath samples are collected through the nostril provides an easy way of avoiding false-positive results for the detection of H. pylori infection. (C) 2004 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.