Stent-Induced Cholangitis Mimicking Biliary Dilatation on Sonography

This study describes the sonographic features of stent-induced cholangitis, which could be mistaken for biliary dilatation and obstruction. It involves six patients with a mean age of 71 years (range, 29–81 years) who underwent endoscopic biliary stenting because of biliary obstruction. Stenting duration varied from nine days to five months. All patients had prestenting and poststenting sonograms. The sonographic characteristics were analyzed in all of the patients, with the diagnosis being confirmed by retrograde cholangiopancreaticography. All patients showed biliary dilatation without ductal wall thickening on prestenting sonograms. Follow-up sonograms demonstrated diffuse hypoechoic ductal wall thickening in all patients. In four patients, the ductal lumen was obliterated by wall thickening, which initially led to a misdiagnosis of persistent biliary dilatation. The degree of ductal wall thickening did not correlate with stenting duration. Diagnosis of stent-induced cholangitis should be considered when hypoechoic and thickened bile duct walls are found on sonography. Careful scanning technique and meticulous assessment of the sonographic images helped to separate the echo-free ductal lumen from the hypoechoic edematous mucosal lining. When evaluating patients following stenting, sonographers may need to obtain fine detailed views of the common bile duct to be able to differentiate ductal wall edema from biliary dilatation.