Biliary Drainage in Altered Anatomy: A Comprehensive Literature Review

Abstract Endoscopic retrograde cholangiopancreatography (ERCP), introduced in 1968, remains the gold standard for managing pancreatobiliary disorders, achieving success rates of nearly 95% in patients with normal anatomy. However, modern surgical interventions, such as Roux-en-Y gastric bypass (RYGB), hepaticojejunostomy, pancreaticoduodenectomy (Whipple procedure), and Billroth II gastrectomy, result in surgically altered anatomies (SAA), complicating biliary interventions due to anatomical distortions, including long afferent limbs and sharp intestinal angulations. Device-assisted enteroscopy-based ERCP (DAE-ERCP), including double-balloon, single-balloon, and spiral enteroscopy, has improved access in SAA, especially RYGB patients, with technical success rates as high as 95%; however, it remains technically demanding and time-intensive. Laparoscopy-assisted ERCP demonstrates a higher technical success rate (>95%), but carries increased invasiveness, prolonged procedure times, and higher adverse event rates, limiting its routine use. Endoscopic ultrasound-guided biliary drainage, comprising rendezvous technique, transmural drainage such as choledochoduodenostomy (CDS) and hepaticogastrostomy (HGS), and antegrade interventions, has emerged as a reliable alternative, showing superior technical success and lower complication rates compared with percutaneous transhepatic biliary drainage. Specifically, EUS-guided transmural techniques (HGS, CDS) offer effective internal drainage in anatomies where conventional approaches fail. The recently developed EUS-directed transgastric ERCP procedure, utilizing lumen-apposing metal stents to create temporary gastro-gastric or jejuno-gastric fistulas, has revolutionized biliary interventions in RYGB, achieving high technical and clinical success rates. Novel and hybrid approaches, including magnetic compression anastomosis, artificial intelligence-assisted navigation, and biodegradable stents, continue to enhance therapeutic possibilities, underscoring an evolving multidisciplinary landscape for biliary interventions in surgically altered anatomy.