Development of a new endoscopy system to visualize bilirubin for the diagnosis of duodenogastroesophageal reflux

OBJECTIVES: Reflux hypersensitivity (RH) is a form of refractory gastroesophageal reflux disease in which duodenogastroesophageal reflux (DGER) plays a role. This study aimed to determine the usefulness of an endoscopy system equipped with image-enhanced technology for evaluating DGER and RH. METHODS: The image enhancement mode for detecting bilirubin and calculated values were defined as the Bil mode and Bil value, respectively. First, the visibility of the Bil mode was validated for a bilirubin solution and bile concentrations ranging from 0.01% to 100% (0.002-20 mg/dL). Second, visibility scores of the Bil mode, when applied to the porcine esophagus sprayed with a bilirubin solution, were compared to those of the blue laser imaging (BLI) and white light imaging (WLI) modes. Third, a clinical study was conducted to determine the correlations between esophageal Bil values and the number of nonacid reflux events (NNRE) during multichannel intraluminal impedance-pH monitoring as well as the utility of esophageal Bil values for the differential diagnosis of RH. RESULTS: Bilirubin solution and bile concentrations higher than 1% were visualized in red using the Bil mode. The visibility score was significantly higher with the Bil mode than with the BLI and WLI modes for 1% to 6% bilirubin solutions (P < 0.05). The esophageal Bil value and NNRE were significantly positively correlated (P = 0.031). The area under the receiver operating characteristic curve for the differential diagnosis of RH was 0.817. CONCLUSION: The Bil mode can detect bilirubin with high accuracy and could be used to evaluate DGER in clinical practice.