Metal or plastic biliary stents placement under Endoscopic Retrograde Cholangiopancreatography(ERCP) is a well-established treatment for patients with benign biliary obstruction to relieve jaundice, a palliative treatment for patients with unresectable malignant pancreaticobiliary obstruction and a bridge to surgery for patients with resectable disease. The main limitation of long time plastic stents is stents occlusion. Biliary plastic stents are changed every 2 to 3 months due to an expected median patency from 77 to 126 days.Metal stents present a lower risk of recurring biliary occlusion, yet high cost and stents occlusion are eventually inevitable. The mechanism of biliary stents occlusion include biliary sludge of the accumulation of bacteria and duodenal biliary reflux .The anti-reflux barrier of Oddi's sphincter disappears after the insertion of biliary stents and the pressure in bile duct lowers the duodenale, which cause the retrograde flow of duodenal material into the biliary ducts. Besides, ordinary biliary plastic stent is short which can also shortens the length of duodenal biliary reflux . Therefore, trying to prevent the duodenal biliary reflux is very important in reducing biliary stents occlusion and it is gradually concerned by clinical researchers. Some studies have showed that plastic stents with antireflux valves can effectively reduce the biliary stent stricture and prolong the stents patency, which means reducing duodenobiliary reflux is surely useful for keeping biliary stent patency.So,we assume to explore an innovatively intraintestinal extended biliary stents (reformed with nasobiliary tube ) as substitution for ordinary biliary plastic stent to prevent the duodenobiliary reflux by extending the length of duodenal content reflux and avoid the stents shift via suspending in intrahepatic duct. In this study,we will design a multicenter stratified randomized controlled trial to compare the patency of intraintestinal extended biliary stents and ordinary plastic biliary stents in patients with malignant or benign biliary obstruction respectively and evaluate the effect of intraintestinal extended biliary stents for the prevention of duodenobiliary reflux.

Metal or plastic biliary stents placement under ERCP is a well-established treatment for patients with benign biliary obstruction to relieve jaundice, a palliative treatment for patients with unresectable malignant pancreaticobiliary obstruction and a bridge to surgery for patients with resectable disease. Single or multiple plastic stents are recommended for patients with benign stricture of the common bile duct or malignant stricture if the expected survival is less than 4 months. The main limitation of long time plastic stents is stents occlusion. Biliary plastic stents are changed every 2 to 3 months due to an expected median patency from 77 to 126 days.Metal stents present a lower risk of recurring biliary occlusion, yet high cost and stents occlusion are eventually inevitable. The mechanism of biliary stents occlusion include biliary sludge of the accumulation of bacteria and duodenal biliary reflux .The anti-reflux barrier of Oddi's sphincter disappears after the insertion of biliary stents and the pressure in bile duct lowers the duodenale, which cause the retrograde flow of duodenal material into the biliary ducts. Besides, ordinary biliary plastic stent is short which can also shortens the length of duodenal biliary reflux . Therefore, trying to prevent the duodenal biliary reflux is very important in reducing biliary stents occlusion and it is gradually concerned by clinical researchers. Some studies have showed that plastic stents with antireflux valves can effectively reduce the biliary stent stricture and prolong the stents patency, which means reducing duodenobiliary reflux is surely useful for keeping biliary stent patency.So,we assume to explore an innovatively intraintestinal extended biliary stents with length of 26cm (reformed with nasobiliary tube ) as substitution for ordinary biliary plastic stent to prevent the duodenobiliary reflux by extending the length of duodenal content reflux and avoid the stents shift via suspending in intrahepatic duct. In this study,we will design a multicenter stratified randomized controlled trial to compare the patency of intraintestinal extended biliary stents and ordinary plastic biliary stents in patients with malignant or benign biliary obstruction respectively and evaluate the effect of intraintestinal extended biliary stents for the prevention of duodenobiliary reflux.

This prospective study will be performed at 6 tertiary hospitals in China.The investigators will recruit patients according to admission criteria and exclusion criteria.The patients stratified by malignant and benign biliary obstruction will be randomized (at a 1:1 ratio) to intraintestinal extended biliary stents group (experimental group) and ordinary plastic biliary stents group (control group).The experimental groups will be placed the intraintestinal extended biliary stents in intrahepatic bile duct in ERCP. The control group will be placed ordinary plastic biliary stents in ERCP. The primary endpoint is the duration of stent patency and the rate of stent occlusion.The secondary outcomes include the mortality of each group、adverse events and the rate of technical success.

Inclusion Criteria:

• Malignant or benign extrahepatic biliary stricture,available for insertion of biliary stents in ERCP to alleviate biliary stricture

Exclusion Criteria:

• Patients with malignant or benign biliary stricture do not agree with endoscopic treatment
• Patients agree with metal biliary stents
• Patients with resectable biliary occlusion
• A guidewire could not be passed through the stricture
• Patients with an expected life survival <3months
• Patients with duodenal obstruction and duodenal endoscopy could not be reached to papillary