Bridging to surgery versus palliation in malignant colorectal obstruction: complication risks and mediation by clinical success.

Self-expandable metal stents (SEMS) are routinely used in malignant colorectal obstruction (MCO) for palliation or as a bridge to surgery. However, the association between treatment intent and complication risk, as well as the potential role of clinical success as an intermediate procedural endpoint, remains unclear. We retrospectively analyzed 413 patients with MCO who underwent SEMS placement between 2014 and 2024. Patients were categorized by therapeutic intent (palliation vs. bridge to surgery), and complication rates were compared. Mediation analysis was performed using the Sobel test, structural equation modeling (SEM), and bootstrap-based causal mediation to assess whether clinical success mediated the relationship between therapeutic purpose and complications. Complications occurred in 60 patients (14.5%). Palliation was associated with a higher complication rate compared to bridging (20.0% vs. 8.0%, p = 0.001). Clinical success showed a statistically significant indirect association in the exploratory mediation analysis Therapeutic intent effects (Sobel p = 0.035). SEM confirmed a positive association between therapeutic purpose and clinical success (standardized β = 0.171, p < 0.001) and a negative association between clinical success and complications (β = - 0.191, p = 0.009). Bootstrap mediation analysis revealed that 13.0% of the total effect was mediated through clinical success (p = 0.031). Therapeutic intent was associated with complication risk after SEMS placement, and clinical success may partially account for this association. However, the modest mediated proportion suggests that complications are likely influenced by multiple additional clinical and procedural factors. Optimizing decompression remains important but should be integrated with careful patient selection and follow-up management, particularly in palliative settings.