Multi-Hole Self-Expandable Metallic Stent for Malignant Distal Biliary Obstruction: A Literature Review.

Endoscopic biliary drainage using self-expanding metal stents (SEMSs) is a standard palliative therapy for cholangitis and obstructive jaundice caused by malignant distal biliary obstruction (MDBO). Fully-covered SEMSs (FC-SEMSs) prevent tumor ingrowth and provide longer patency; however, recent advances in chemotherapy have increased stent migration due to tumor shrinkage, resulting in reduced functional patency compared with uncovered SEMSs. Partially covered SEMSs can reduce migration but are often difficult to remove after deployment. In addition, adverse events such as acute pancreatitis and cholecystitis remain a concern with FC-SEMSs. To address these limitations, Dr. Kobayashi introduced a novel porous SEMS with multiple side holes in the covering membrane (MH-SEMSs) in 2019. This design allows limited bile duct epithelial ingrowth through side holes, providing anchorage while maintaining removability. The side-hole structure may also reduce cholecystitis and pancreatitis by preserving flow through the pancreatic and cystic duct orifices. Over five years since their introduction, clinical evidence supporting MH-SEMSs has steadily increased. This review summarizes current data and explores future perspectives for MH-SEMS use in MDBO management.