Endoscopic Stenting for Unresectable Malignant Hilar Biliary Obstruction: Where Do We Stand Today? A Narrative Review.

Malignant hilar biliary obstruction (MHBO) is a complex clinical condition commonly observed in individuals with advanced cholangiocarcinoma and other hepatobiliary malignancies. Endoscopic stenting remains the primary palliative intervention for unresectable cases; however, the optimal strategy has not been clearly defined owing to the anatomical intricacies of the hilar region and the heterogeneity of disease presentation. This narrative review summarizes current evidence and ongoing debates on functional liver volume-based drainage, unilateral versus bilateral stenting, stent type selection, and above-the-papilla approaches. In addition, we highlight recent progress in endoscopic ultrasound-guided biliary drainage as a promising alternative or complementary approach when conventional transpapillary drainage proves inadequate. With recent advances in systemic therapies, including immunotherapy, patient survival has improved, underscoring the need for durable, reintervention-friendly stent strategies. Although uncovered metal stents have long been regarded as the standard for unresectable cases, their limitations in reintervention have prompted renewed consideration of both stent type and drainage technique. Robust prospective studies remain essential to establish standardized, evidence-based guidelines that optimize patient benefit and improve long-term outcomes in unresectable MHBO.