Incidence and Significance of Biliary Stricture in Chronic Pancreatitis Patients Undergoing Extracorporeal Shock Wave Lithotripsy for Obstructing Pancreatic Duct Stones

BACKGROUND/AIMS: This study assessed the significance of biliary stricture in symptomatic chronic pancreatitis patients requiring extracorporeal shock wave lithotripsy (ESWL) and endoscopic retrograde cholangiopancreatography (ERCP) to remove obstructing pancreatic calculi. METHODS: A total of 97 patients underwent ESWL followed by ERCP to remove pancreatic calculi between October 2014 and October 2017 at Virginia Mason Medical Center. Significant biliary stricture (SBS) was defined as a stricture with upstream dilation on computed tomography scan or magnetic resonance cholangiopancreatography scans accompanied by cholestasis and/or cholangitis. SBS was initially managed by either a plastic stent or fully covered self-expandable metallic stent (fcSEMS). If the stricture did not resolve, the stent was replaced with either multiple plastic stents or another fcSEMS. Data were collected by retrospectively reviewing the medical records. RESULTS: Biliary strictures were noted in approximately one-third of patients (34/97, 35%) undergoing ESWL for pancreatic calculi. Approximately one-third of the biliary strictures (11/34, 32%) were SBS. Pseudocysts were more frequently found in those with SBS (36% vs 8%, p=0.02), and all pseudocysts in the SBS group were located in the pancreatic head. The initial stricture resolution rates with fcSEMSs and plastic prostheses were 75% and 29%, respectively. The overall success rate for stricture resolution was 73% (8/11), and the recurrence rate after initial stricture resolution was 25% (2/8). CONCLUSIONS: Although periductal fibrosis is the main mechanism underlying biliary stricture development in chronic pancreatitis, inflammation induced by obstructing pancreatic calculi, including pseudocysts, is an important contributing factor to SBS formation during the acute phase.