Timing of sampling in endoscopic 13C-urea breath test for H. pylori infection

Background The endoscopic 1 3 C-urea breath test (EUBT) is a useful diagnostic method for Helicobacter pylori. Objectives The aim of our study was to determine timing of sampling in EUBT on the basis of the time course profile of 1 3 CO 2 concentration and practical convenience. Methods Thirty-five patients participated in this study. Bacterial culture, a rapid urease test, an antigen detection kit, and histological tests were used for diagnosing H. pylori infection. After seven breath samples were collected, gastrointestinal endoscopy (i. e., observation of mucosa and biopsy) was performed. In the end of endoscopy process, 1 3 C-urea dissolved in indigocarmine solution was sprayed over the entire gastric mucosa (time 0) and the endoscope was taken out from the patient. Breath samples were collected at 3, 5, 10, 20, 30, 45 and 60min under normal respiration. Breath samples were analyzed for 1 3 CO 2 with an infrared spectrometer. Results Our study demonstrated that 1 3 CO 2 concentration at 30 min was best to judge the infection and that the 3-min breath sample was available as the base line control. Based on the receiver-operating characteristic curve for 35 patients, the most appropriate cut-off value was identified as 2 %o. Conclusions In EUBT, the difference of 1 3 CO 2 concentrations between 3 and 30min is a good indicator for assessing H. pylori infection. Breath sampling before the endoscopy is not required.