Impact of reducing duodenobiliary reflux on biliary stent patency: an in vitro evaluation and a prospective randomized clinical trial that used a biliary stent with an antireflux valve

BackgroundThe mechanisms leading to occlusion of plastic biliary stents (PBS) are not known.ObjectiveTo evaluate the impact of reducing duodenobiliary reflux on stent patency rate.DesignA newly designed antireflux PBS (AR-PBS) was tested in vitro by using ox bile. A prospective randomized trial in human beings was conducted.SettingTertiary medical center.PatientsPatients with malignant bile-duct strictures were studied.InterventionsA PBS or an AR-PBS stent was placed by using standard techniques, and the patients were followed at regular intervals. Patients presenting with stent occlusion underwent re-stent placement with either a PBS or a metal stent.Main Outcome MeasurementsIn vitro: resistance to retrograde flow and comparison of the basal and peak antegrade flow pressures between the 2 stents. In vivo: stent patency rates, complications, and the efficacy of the stents in improving the liver test.ResultsThe AR-PBS stent could withstand a retrograde pressure gradient of >320 mm Hg compared with <1 mm Hg for the PBS. Secondary to the siphon effect of the valve, the antegrade flow resistance offered by the AR-PBS was on the negative side for all flow rates compared with PBS (P < .001). The median patency of the AR-PBS in human studies was 145 days (range, 52-252 days) compared with 101 days (range, 41-210 days) for the PBS (P = .002). Both stents were equally effective in improving the liver test, and complication rates were similar in the 2 groups.LimitationsThe occluded stents were not examined microscopically.ConclusionsThe antireflux biliary stent remains patent for a longer time and hence duodenobiliary reflux may be contributing to stent occlusion.