Can biliary stents become occluded by biofilm and sludge?

Biliary stents restore drainage but can later fail through intraluminal obstruction. The claim is strongly supported, especially for plastic stents: bacterial biofilm and sludge can obstruct the lumen, re-establish biliary obstruction, and materially increase cholangitis risk.

Clinical evidence

• In a prospective cohort of 343 stents, 20% became occluded; longer dwell time and greater microbial burden were independently associated with sludge accumulation.
• In an explant study of 81 patients, polymicrobial biofilms were recovered from 90.1% of removed stents. Longer indwelling duration, cholangitis, and smaller stent diameter correlated with greater biofilm formation.
• Occlusion is an established cause of recurrent biliary obstruction after initially successful stenting, clinically presenting with recurrent jaundice, cholestatic laboratory abnormalities, and/or cholangitis.
• Cholangitis occurred in 38.5% of patients with stent occlusion versus 9.1% without occlusion (P<0.001). In malignant distal obstruction, occlusion accounted for 71.4% of plastic-stent dysfunction among patients developing cholangitis.

Mechanism and clinical implications

• Biofilm provides an adherent matrix that retains bile constituents, microbial products, debris, and dietary fibres. Bacterial beta-glucuronidase can promote bilirubin deconjugation and calcium bilirubinate precipitation.
• The resulting sludge may contain biofilm, proteins, fibres, calcium bilirubinate, calcium palmitate, cholesterol, and occasionally fungi, progressively narrowing the lumen.
• Recurrent obstruction is not always biofilm/sludge-mediated: stent migration and, particularly with self-expanding metal stents, tumor ingrowth or overgrowth can also impair drainage.
• Suspected cholangitis with an obstructed stent warrants urgent assessment, antibiotics when infection is suspected, and biliary source control—typically ERCP-based drainage. Antibiotics alone do not correct an obstructed biliary system.

Bottom line

• Biofilm-associated sludge is an established, clinically important mechanism of biliary-stent occlusion—most clearly in plastic stents—causing recurrent bile-flow obstruction and substantially raising the risk of cholangitis.