Segment-Specific Occlusion of Retrieved Plastic Biliary Stents: Direct Quantification and Microbial and Material Determinants

Plastic stents (PS) are widely used for biliary drainage, with occlusion mainly caused by biofilm formation and sludge accumulation. However, direct evaluation of luminal occlusion remains limited, and its spatial distribution is poorly understood. This study aimed to quantify luminal occlusion in retrieved PS and identify associated factors.

In this prospective observational study, 64 patients (196 stents) undergoing scheduled PS exchange at approximately 3-month intervals were included. Retrieved stents were divided into proximal, central, and distal segments, and occlusion was quantified using ImageJ. Clinical, microbiological, and device-related variables were analyzed. Multivariable linear regression was used to identify independent factors associated with occlusion.

The mean occlusion rate was 28.8% ± 29.8%. Occlusion was significantly higher in the proximal segment than in the central and distal segments (35.5% vs. 25.8% and 25.0%; p < 0.05). Multivariable analysis showed that age > 65 years (β = 11.62, p = 0.006), Enterococcus-positive bile culture (β = 16.00, p = 0.012), and probiotic use (β = 14.91, p = 0.007) were independently associated with increased occlusion. Stent brand was also associated with the degree of occlusion.

Plastic stent occlusion is segment-dependent, predominantly affecting the proximal portion, and is associated with microbiological and material-related factors. Direct quantification may help optimize stent design and management.