Endoscopic management of malignant hilar biliary obstruction: The evolving role of endoscopic ultrasound-guided biliary drainage

Abstract

In this editorial, we comment on the article by Pietrzak et al published in the recent issue of the World Journal of Gastrointestinal Endoscopy. Malignant hilar biliary obstruction remains a formidable challenge for endoscopists. While endoscopic retrograde cholangiopancreatography continues to represent the cornerstone of biliary drainage, malignant hilar biliary obstruction often requires a multimodal approach that incorporates percutaneous-guided techniques, either as complementary or salvage strategies. Emerging evidence also supports the integration of endoscopic ultrasound-guided biliary drainage as a planned adjunct in selected cases to optimize biliary drainage, reduce the need for re-intervention, and improve clinical outcomes. In this editorial, we review current guideline recommendations and key technical considerations, emphasizing the role of endoscopic ultrasound-guided biliary drainage in expert hands for patients with complex hilar anatomy or incomplete drainage after endoscopic retrograde cholangiopancreatography.

Key Words: Biliary tract obstruction; Cholangiocarcinoma; Endoscopic retrograde cholangiopancreatography; Endosonography; Biliary drainage; Endoscopic ultrasound; Interventional endoscopy

Core Tip: Malignant hilar biliary obstruction often requires more than endoscopic retrograde cholangiopancreatography (ERCP) to achieve adequate biliary drainage. Endoscopic ultrasound-guided biliary drainage is an emerging adjunct for patients in whom ERCP is insufficient or technically challenging. As part of a multimodal strategy, including ERCP and percutaneous drainage, endoscopic ultrasound-guided biliary drainage can improve drainage, reduce re-interventions, and enhance outcomes. Expanding expertise and specialized centers is essential to define its role in malignant hilar biliary obstruction management.

This editorial refers to “Endoscopic treatment of malignant hilar biliary obstruction: A retrospective cohort study” by Pietrzak et al, 2025; https://doi.org/10.4253/wjge.v17.i12.110432.

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INTRODUCTION

Malignant hilar biliary obstruction (MHBO) is a complex clinical condition frequently encountered in patients with cholangiocarcinoma, pancreatic cancer, and other gastrointestinal malignancies. It remains a significant therapeutic challenge for endoscopists due to its association with severe jaundice, cholestasis, and liver dysfunction, necessitating timely and effective intervention.

The recent retrospective study by Pietrzak et al[1] published in the World Journal of Gastrointestinal Endoscopy reported 164 patients with MHBO treated through endoscopic retrograde cholangiopancreatography (ERCP)-based interventions and demonstrated that uncovered self-expandable metal stents (SEMS) provided the longest patency and survival, particularly when combined with adjunctive modalities such as radiofrequency ablation and chemotherapy.

Traditionally, ERCP has been the mainstay of management for biliary drainage and remains the gold standard for biliary decompression in patients with distal biliary obstruction[2].

However, its role in hilar biliary obstruction, especially in the setting of complex malignant strictures or post-surgical anatomical alterations, is more limited. The principal limitation of ERCP in this context lies in the difficulty of achieving adequate and comprehensive biliary drainage. Indeed, current guidelines recommend draining more than 50% of the functional liver volume to optimize clinical outcomes, while incomplete drainage is associated with persistent jaundice, recurrent cholangitis, and reduced survival[3]. However, evidence suggests a direct relationship between the extent of hepatic drainage and the feasibility of oncologic palliative treatment, with drainage of up to 80% of the liver volume being associated with improved outcomes, especially in cases where less than half of the liver parenchyma is involved by tumor infiltration[4].

While unilateral stent placement may be effective in strictures that do not involve the hepatic confluence (such as Bismuth types I), it is often insufficient in advanced malignant strictures involving both hepatic ducts (Bismuth type II or higher). In these settings, incomplete biliary drainage frequently occurs, resulting in persistent cholestasis and an increased need for re-intervention. Consequently, bilateral stenting is generally considered the optimal approach to achieve adequate drainage[5].

Nonetheless, the technical challenges associated with ERCP in hilar obstruction, such as inadequate drainage, can significantly impact clinical outcomes, highlighting the need for alternative or complementary strategies[6].

Percutaneous transhepatic biliary drainage (PTBD) has traditionally been employed when ERCP fails, yet it carries drawbacks such as external drains, discomfort, and infection risk[6].

Thus, the search for an endoscopic approach that avoids PTBD-related morbidity while overcoming ERCP’s anatomical constraints has driven the evolution of endoscopic ultrasound (EUS)-guided biliary drainage (EUS-BD).

THE EVOLVING ROLE OF EUS-BD

The advent of EUS-BD has introduced a minimally invasive alternative that enables access to intrahepatic ducts beyond the reach of ERCP. The concept of EUS-BD was first introduced as a novel technique by Giovannini et al[7] in 2001, with promising outcomes for patients with distal biliary obstruction. Initially developed as a salvage technique after failed ERCP, EUS-BD has evolved into a complementary approach with an expanding range of indications[8]. EUS-BD offers clinical advantages compared with ERCP, including a lower risk of post-procedural pancreatitis, reduced tumor ingrowth, and fewer stent-related dysfunctions. Moreover, its application has since expanded to include patients with complex malignant hilar obstructions, especially when ERCP fails or is technically difficult[9-12].

A wide variety of EUS-BD techniques have been described for the management of MHBO. The most commonly used approaches include: (1) EUS-guided hepaticogastrostomy (EUS-HGS); (2) EUS-guided hepaticoduodenostomy (EUS-HDS); (3) The “bridging” technique (placement of a stent connecting the left and right hepatic systems); (4) EUS-guided antegrade stenting; (5) EUS-guided rendezvous; and (6) Combined ERCP and EUS (CERES) (Table 1)[13-23].

Table 1 Endoscopic ultrasound-guided biliary drainage techniques in malignant hilar biliary obstruction.

Technique	Description of technique	Technical efficacy	Clinical efficacy	Adverse events	Key considerations
EUS-HGS	EUS-guided creation of a fistula between the left intrahepatic bile duct and the stomach with plastic or metal stent placement	97%	88%	10%-35%	Most established technique; drains only left system; optimal for communicating ducts (Bismuth I)
EUS-HDS	EUS-guided drainage of the right intrahepatic bile duct into the duodenum	97%	80%	20%	Technically demanding; useful for right system drainage and in combination with HGS. Small series
Bridging technique	EUS-guided transgastric placement of a stent across the hilar stricture connecting left and right ducts, followed by HGS	90%	83%	33%	Allows complete liver drainage using EUS alone; high technical complexity
EUS-HDGS	Simultaneous EUS-guided hepaticogastrostomy and hepaticoduodenostomy for bilateral drainage	87%	75%	25%	Promising fully EUS-based bilateral approach; requires advanced expertise. Small series
CERES	ERCP drainage of one hepatic system combined with EUS-guided drainage of the contralateral system	84%	79%	26%	Hybrid approach; lower reintervention rate than PTBD

EUS: Endoscopic ultrasound; HGS: Hepaticogastrostomy; HDS: Hepaticoduodenostomy; EUS-HDGS: Endoscopic ultrasound-guided hepatico-duodeno-gastrostomy; CERES: Combined endoscopic retrograde cholangiopancreatography and endoscopic ultrasound-biliary drainage; ERCP: Endoscopic retrograde cholangiopancreatography; PTBD: Percutaneous transhepatic biliary drainage.

The primary objective of all these techniques is to achieve effective decompression of the largest possible volume of functional liver parenchyma[4]. From a conceptual standpoint, EUS-BD techniques in MHBO can be categorized according to their primary drainage goal, reflecting the extent of liver parenchyma targeted for decompression. The selection of the optimal approach depends on multiple factors, including anatomical considerations (such as papillary accessibility, location and extent of biliary stricture, and presence of hepatic lobar atrophy), patient clinical status, and operator expertise.

EUS-HGS has become the most frequently performed EUS-guided technique for MHBO, since the first reported case described by Giovannini et al[24] in 2003 in a surgically altered patient. However, the main limitation of EUS-HGS is the possibility to drain only the left intrahepatic biliary system. Indeed, optimal outcomes of EUS-HGS have been reported primarily in patients with communication between the left and right biliary systems, in whom a single stent may be sufficient (as in Bismuth type I stenosis). Consequently, the applicability of EUS-HGS is limited in patients with more complex hilar strictures, particularly in Bismuth type II, III, or higher, lesions.

To drain non-communicating biliary systems, several novel techniques have been introduced. The CERES approach involves ERCP-based drainage of one biliary system combined with EUS-guided biliary drainage (either EUS-HGS or EUS-HDS) of the contralateral, undrained system[17].

In addition, exclusively EUS-based strategies aimed at achieving complete liver drainage have been developed. Among these, the so-called “bridging” technique consists of EUS-guided transgastric placement of an uncovered stent across the hilar stricture to connect and drain the right biliary system, followed by EUS-HGS to ensure complete drainage into the stomach[14,18] but this technique is only possible in patients with type II stenosis. Another exclusively EUS-based option is the combined use of EUS-HGS and EUS-HDS, recently termed EUS-guided hepatico-duodeno-gastrostomy, that has been described as a novel approach for bilateral biliary drainage in MHBO, using both plastic and metallic stents[21].

Collectively, these EUS-based techniques represent promising and evolving strategies for obtaining comprehensive biliary decompression in patients with complex hilar obstruction, particularly in cases with non-communicating biliary systems, where conventional endoscopic or percutaneous approaches may be limited.

EFFICACY, SAFETY, AND TECHNICAL CONSIDERATIONS OF EUS-BD IN MHBO

EUS-BD in MHBO encompasses several distinct techniques, each associated with a different degree of technical complexity. Data extracted from major studies indicate that the technical and clinical success rates of EUS-BD across various EUS-based approaches in MHBO range from 84% to 100% and 75% to 100%, respectively, depending on the technique used and the study setting. Overall adverse event rates have been reported to vary between 10% and 35%, with variability across techniques and patient populations[15,25,26]. The most reported complications include stent migration/malfunction, bile leakage with peritonitis, bleeding, cholangitis, sepsis or bacteremia, and vascular injury, with reintervention required in approximately 16%-23% of cases. Procedure-related mortality and the need for subsequent surgical intervention have also been described, underscoring the technical complexity and potential risks associated with these procedures.

It is important to note that most available data originate from highly experienced, high-volume centers. Therefore, the reported efficacy and safety outcomes may not be generalizable to routine clinical practice worldwide.

Indeed, EUS-BD, particularly in the setting of MBHO, remains a technically demanding and complex procedure. Accessing the biliary system through the gastric or duodenal wall requires advanced technical expertise. Operators must possess comprehensive proficiency in both ERCP and interventional EUS, as well as thorough familiarity with dedicated endoscopic devices[27]. Nevertheless, the learning curve for EUS-BD in MHBO remains steep and prolonged, indicating that these procedures should be adopted only by highly experienced endoscopists working in specialized referral centers. In line with these considerations, the current international guidelines on therapeutic EUS recommend some procedures, such as EUS-HDS, to be performed only in expert centers and after careful evaluation of all therapeutic possibilities[28].

Despite these considerations, it should be acknowledged that ERCP is not feasible, difficult or potentially dangerous in patients with inaccessible papilla, such as those with altered anatomy or duodenal tumor involvement, and that PTBD is not without limitations, including procedure-related complications and significant patient discomfort. In this setting EUS-BD has become an effective alternative to both ERCP and PTBD, particularly in the hands of experienced endoscopists.

TECHNICAL SELECTION AND CLINICAL DECISION-MAKING

As previously mentioned, the selection of the optimal EUS-BD strategy in MHBO should be individualized according to biliary anatomy, Bismuth classification, and overall clinical context. In less complex strictures, such as Bismuth type I, ERCP-based drainage remains the preferred first-line approach, with EUS-guided techniques mainly serving as complementary or salvage options when adequate liver drainage cannot be achieved.

In more advanced hilar strictures (Bismuth type II-IV), particularly in the presence of non-communicating biliary systems, EUS-guided strategies aimed at bilateral or extended liver drainage may offer specific advantages. In this setting, CERES or exclusively EUS-based techniques (bridging technique or EUS-guided hepatico-duodeno-gastrostomy), can be considered in highly selected patients.

It should be emphasized that the evidence supporting these advanced EUS-guided strategies is still limited and mainly derived from small retrospective series conducted in expert centers[13,18-22]. Although feasibility and short-term clinical outcomes appear promising, comparative data and long-term results are lacking, and several open questions remain regarding optimal patient selection, reproducibility, and durability of stent patency.

FUTURE STENT INNOVATIONS

A variety of stents are currently used for EUS-BD, including fully covered and partially covered SEMSs, plastic stents, and lumen-apposing metal stents[24]. In parallel with the growing role of EUS-HGS, dedicated stent designs are being developed to enhance procedural safety and facilitate stent removability across different clinical scenarios[29-33].

Semi-covered dedicated SEMSs with anti-migration flared end (Giobor^® stent) represent an early step in this direction by combining a covered portion, designed to reduce bile leakage along the transmural tract, with an uncovered intrahepatic segment that preserves drainage from adjacent biliary branches[29]. This configuration supports effective biliary decompression while providing anchorage within the intrahepatic ducts, thereby contributing to procedural stability and safety.

More recently, fully covered-SEMSs incorporating side-hole fenestrations at the intrahepatic end have emerged as a promising innovation[33]. By introducing multiple microfenestrations, these stents aim to preserve bile flow from adjacent intrahepatic ducts while maintaining full coverage of the stent body. This design may support physiological drainage even in complex biliary anatomy and retains the advantages of improved safety and ease of stent removal. Collectively, these evolving stent technologies reflect ongoing efforts to optimize outcomes of EUS-guided hepato-gastrostomy through tailored solutions that prioritize both safety and removability.

CONCLUSION

EUS-BD is an emerging and increasingly adopted technique for the management of MHBO, particularly in patients in whom ERCP alone is insufficient or technically challenging. As part of a multimodal strategy, EUS-BD can significantly improve biliary drainage, reduce the need for re-intervention, and enhance clinical outcomes in complex MHBO cases. The primary goal in MHBO management remains the drainage of the maximum possible liver parenchyma, and in this context, EUS-BD should be regarded as “another arrow in our therapeutic quiver”, along with ERCP and PTBD. Further research, as well as the expansion of experienced operators and specialized centers, is essential to define the true role of EUS-guided interventions in the multimodal management of MHBO.