Risk factors for proximal migration of biliary tube stents

AIM: To analyze the risk factors for biliary stent migration in patients with benign and malignant strictures. METHODS: Endoscopic stent placement was performed in 396 patients with bile duct stenosis, at our institution, between June 2003 and March 2009. The indications for bile duct stent implantation included common bile duct stone in 190 patients, malignant lesions in 112, chronic pancreatitis in 62, autoimmune pancreatitis in 14, trauma in eight, surgical complications in six, and primary sclerosing cholangitis(PSC) in four. We retrospectively examined the frequency of stent migration, and analyzed the patient factors(disease, whether endoscopic sphincterotomy was performed, location of bile duct stenosis and diameter of the bile duct) and stent characteristics(duration of stent placement, stent type, diameter and length). Moreover, we investigated retrieval methods for migrated stents and their associated success rates. RESULTS: The frequency of tube stent migration inthe total patient population was 3.5%. The cases in which tube stent migration occurred included those with common bile duct stones(3/190; 1.6%), malignant lesions(2/112; 1.8%), chronic pancreatitis(4/62; 6.5%), autoimmune pancreatitis(2/14; 14.3%), trauma(1/8; 12.5%), surgical complications(2/6; 33.3%), and PSC(0/4; 0%). The potential risk factors for migration included bile duct stenosis secondary to benign disease such as chronic pancreatitis and autoimmune pancreatitis(P = 0.030); stenosis of the lower bile duct(P = 0.031); bile duct diameter > 10 mm(P = 0.023); duration of stent placement > 1 mo(P = 0.007); use of straight-type stents(P < 0.001); and 10-Fr sized stents(P < 0.001). Retrieval of the migrated stents was successful in all cases. The grasping technique, using a basket or snare, was effective for pig-tailed or thin and straight stents, whereas the guidewire cannulation technique was effective for thick and straight stents. CONCLUSION: Migration of tube stents within the bile duct is rare but possible, and it is important to determine the risk factors involved in stent migration.