For many years, ERCP has been the mainstay of pancreatobiliary intervention. As therapeutic EUS continues to evolve, however, EUS-BD is becoming an increasingly important direction in gastrointestinal intervention.

This shift is not only changing the route of biliary drainage. It is also raising the technical requirements for upstream catheter shafts, access sheaths, stent delivery systems, and composite medical tubing.

EUS-BD, or Endoscopic Ultrasound-Guided Biliary Drainage, is a technique in which physicians use endoscopic ultrasound to identify target structures such as the bile duct or intrahepatic bile duct, and then create a new drainage pathway from the stomach, duodenum, or other gastrointestinal lumen.

Its clinical value is clear: when conventional ERCP fails to achieve biliary drainage, EUS-BD can provide an endoscopic alternative and reduce reliance on percutaneous external drainage approaches such as PTBD.

ESGE guidelines have also recommended EUS-BD over PTBD after failed ERCP in malignant distal biliary obstruction, provided that local expertise is available.

1. Why ESGE Matters

ESGE stands for the European Society of Gastrointestinal Endoscopy.

It is not a regulatory authority, nor is it an endorsement body for any specific device company. Rather, it is one of the most influential professional societies in the field of gastrointestinal endoscopy. ESGE publishes evidence-based guidelines and consensus statements that help guide clinical decision-making across different diseases and endoscopic procedures.

For medical device companies, the importance of ESGE guidelines goes beyond the mention of a specific procedure. They reflect changes in clinical pathways, procedural acceptance, and future device requirements.

When EUS-BD is included as an important part of therapeutic EUS, it indicates that this technique is no longer limited to exploratory use in a small number of expert centers. Under defined indications and appropriate clinical expertise, EUS-BD is gradually moving toward more systematic clinical adoption.

For the device industry, this sends a clear signal:

Gastrointestinal intervention is expanding from traditional ERCP accessories toward a more complex therapeutic EUS device ecosystem.

2. What Are the Main EUS-BD Techniques?

EUS-BD is not a single procedure. It refers to a group of endoscopic ultrasound-guided biliary drainage techniques. Different approaches involve different anatomical routes, device combinations, and catheter structure requirements.

EUS-CDS: EUS-Guided Choledochoduodenostomy

EUS-CDS, or EUS-guided choledochoduodenostomy, typically creates a drainage pathway between the common bile duct and the duodenum.

Because the access route is relatively short, EUS-CDS is often considered in distal biliary obstruction.

From a device perspective, EUS-CDS requires smooth procedural continuity across puncture, tract dilation, stent delivery, and stent deployment. Distal positioning, deployment stability, pushability, and kink resistance of the delivery system are all critical.

EUS-HGS: EUS-Guided Hepaticogastrostomy

EUS-HGS, or EUS-guided hepaticogastrostomy, usually involves puncturing the left intrahepatic bile duct from the stomach and creating a drainage pathway between the intrahepatic bile duct and the gastric lumen.

Compared with EUS-CDS, EUS-HGS generally involves a longer and more complex access route. This places higher demands on shaft support, flexibility, trackability, and distal control.

The catheter system must be able to pass through the curved endoscope working channel, maintain stable delivery over a longer pathway, and support accurate stent deployment.

EUS-AGS / EUS-ABS: Antegrade Stenting or Antegrade Biliary Intervention

In some cases, physicians establish access under EUS guidance and then perform antegrade stenting or other antegrade biliary interventions along the bile duct.

These procedures require reliable guidewire tracking, long-distance pushability, stent delivery, and controlled deployment. The catheter shaft must provide sufficient support under bending conditions, while avoiding excessive stiffness that may increase the risk of tissue trauma.

3. From Access-Oriented Devices to Integrated Catheter Systems

Traditional ERCP devices are mainly designed around natural anatomical pathways. Guidewires, sphincterotomes, stone extraction balloons, retrieval baskets, biliary stents, and delivery systems are used to achieve access, dilation, stone removal, drainage, and stent placement.

EUS-BD is different.

It does not simply follow an existing natural pathway. Instead, it creates a new drainage route under ultrasound guidance.

A typical EUS-BD procedure may involve:

・Ultrasound localization

・Puncture

・Guidewire placement

・Tract dilation

・Stent delivery

・Stent deployment

・Drainage maintenance

These steps occur in sequence and place more comprehensive demands on the device system.

The catheter must pass through the endoscope working channel. The distal end must remain stable and controllable. The shaft must provide sufficient pushability. The lumen must resist collapse under bending. The inner surface must allow smooth passage of guidewires and devices. The stent deployment process must be predictable and controlled.

As EUS-BD gains traction, downstream device companies no longer need only a simple tube. They increasingly need multi-layer, multi-lumen, and reinforced composite catheter systems that can support more demanding procedures.

4. Why Multi-Layer Structures Matter

The value of a multi-layer structure lies in assigning different material properties to different functional layers of the catheter.

In EUS-BD-related devices, common structural requirements include:

・A low-friction inner layer to support guidewire, pusher, or stent system movement

・A reinforced middle layer to provide support, kink resistance, torque response, and dimensional stability

・A flexible outer layer to improve trackability, abrasion resistance, and atraumatic passage

・A smooth distal transition created through different material hardness levels

A single material often cannot meet all these requirements at the same time.

If the material is too soft, the device may lack pushability. If it is too stiff, it may be difficult to navigate through the curved endoscope channel and may increase the risk of tissue trauma.

Multi-layer structures make it possible to balance these requirements within a limited outer diameter.

For example, a PTFE liner can reduce internal friction, a PEBAX outer layer can provide flexible transition, and a metallic braid or coil layer can improve support and kink resistance.

For stent delivery systems, dilators, and drainage access devices, this type of structure is becoming increasingly important.

5. Why Multi-Lumen Structures Matter

EUS-BD-related devices are becoming more functionally integrated. A single lumen is often not enough to support all required functions.

In complex gastrointestinal intervention devices, different lumens may be used for:

・Guidewire passage

・Contrast injection or fluid delivery

・Irrigation or drainage

・Traction control

・Deployment mechanisms

・Electrode or energy transmission

・Radiopaque marker or positioning-related structures

The purpose of a multi-lumen structure is to organize multiple functions within a limited outer diameter.

This is especially important in gastrointestinal intervention, where the endoscope working channel has strict size limitations. The device cannot simply become larger, but physicians still expect fewer device exchanges, higher procedural efficiency, and more stable deployment.

A multi-lumen tube is therefore not just a tube with “more holes.” It is the structural foundation for integrating guidewires, fluids, control mechanisms, and functional components into one device platform.

6. Why Composite Structures Matter

Composite structures address the mechanical and functional challenges that cannot be solved by a single extruded tube.

EUS-BD devices often operate under combined conditions involving bending, pushing, rotation, and deployment. The catheter shaft must be flexible but supportive, thin-walled but kink-resistant, easy to track but capable of maintaining distal control.

These conflicting requirements make composite construction essential.

Typical structural solutions include:

・Braided reinforced tubing

・Coil reinforced tubing

・PTFE-lined composite tubing

・PEBAX jacketed extrusion

・FEP heat-shrink composite structures

・Metal-reinforced delivery sheaths

・Multi-durometer composite shafts

・Distal tip forming and thermal shaping

These structures can improve pushability, kink resistance, torque response, and dimensional stability in curved access pathways.

For EUS-CDS, EUS-HGS, and stent delivery systems, composite construction is not an optional feature. It is a fundamental requirement for reliable device performance.

7. Why Choose ECO Polymer?

The core challenge of therapeutic EUS devices such as EUS-BD is not simply whether a tube can be made.

The real challenge is whether low friction, kink resistance, pushability, torque response, flexible transition, functional integration, and production consistency can all be achieved within a limited outer diameter.

This is exactly where ECO Polymer focuses its expertise.

ECO Polymer specializes in medical catheter tubing and precision polymer components. Serving applications across gastrointestinal intervention, urology, vascular intervention, structural heart, electrophysiology, and endoscope components, ECO has built a process platform covering material extrusion, reinforced composite structures, post-processing, and assembly support.

For complex gastrointestinal interventional device development, ECO Polymer can provide support in the following areas.

1. Multi-Material Precision Extrusion

For EUS-BD, ERCP, stent delivery systems, dilators, sheaths, and related products, ECO Polymer can process a wide range of medical-grade polymers, including PEBAX, PTFE, FEP, PEEK, TPU, HDPE, and PA.

This enables ECO to provide not only single-material tubing, but also material selection and structural optimization based on the actual working conditions of the customer’s device.

2. Multi-Layer Composite and Reinforced Structures

EUS-BD-related devices must maintain stable delivery performance within curved pathways. A single-layer tube often cannot provide the right balance between flexibility and support.

ECO Polymer supports the development of multi-layer composite tubing, braided reinforced tubing, coil reinforced tubing, PTFE-lined composite tubing, jacketed extrusion, and thermally bonded composite structures.

By combining a low-friction inner layer, reinforced middle layer, and flexible outer jacket, ECO can help customers improve trackability, kink resistance, pushability, and deployment stability within the endoscope working channel.

3. Multi-Lumen and Complex Profile Design

As therapeutic EUS devices integrate more functions, the catheter interior is no longer a simple channel. It may need to accommodate guidewires, fluid injection, contrast delivery, traction elements, deployment mechanisms, or other functional components.

ECO Polymer has experience in multi-lumen tubing and complex profile development. Based on customer product requirements, ECO can support different lumen layouts, including guidewire lumens, injection lumens, traction lumens, and working lumens.

This capability helps downstream device companies integrate more functions within a limited outer diameter, reduce device exchanges, improve procedural efficiency, and create greater product differentiation.

4. Post-Processing and Detail Engineering

The performance of a complex catheter is not determined by extrusion alone. Post-processing details often play an equally important role.

ECO Polymer provides precision cutting, hole punching, flaring, tip forming, thermal bonding, heat setting, laser marking, localized jacketing, and component pre-assembly support.

For EUS-BD-related devices, the smoothness of the distal transition, lumen integrity, outer diameter stability, delivery smoothness, and deployment control can directly affect product verification results.

ECO’s value is not limited to supplying tubing. ECO helps customers turn catheter designs from drawings into verifiable, assembly-ready, and scalable product components.

5. Quality System Support from Prototyping to Volume Production

Advanced gastrointestinal interventional devices such as EUS-BD require high consistency. A successful prototype does not guarantee stable performance in design verification, registration testing, or batch production.

ECO Polymer operates under an ISO 13485 quality management system and a cleanroom manufacturing environment. This allows ECO to support customers from early-stage prototyping and pilot validation to scale-up and volume production.

During project development, ECO can support process control around key parameters such as dimensional tolerance, concentricity, wall thickness, lumen stability, interlayer bonding, and batch-to-batch consistency. This helps customers reduce process risk when moving from R&D to production.

6. Application Understanding Beyond the Drawing

The catheter structures used in EUS-BD, ERCP, and other gastrointestinal interventional devices must take into account the clinical pathway, endoscope working channel, guidewire compatibility, stent delivery, deployment feel, and assembly method.

ECO Polymer has long served medical device customers and is able to discuss structural solutions based on specific application scenarios, rather than only manufacturing a tube according to dimensional requirements.

At the early development stage, ECO can help customers evaluate:

・Which layer requires low friction

・Which segment requires higher support

・Whether the distal end needs a softer transition

・Whether braid or coil reinforcement is needed

・Whether the multi-lumen layout may affect wall thickness or eccentricity

・Whether post-processing may cause lumen collapse, cracking, or dimensional rebound

・Whether the current structure is feasible for scalable production

For complex gastrointestinal interventional devices, this application-driven engineering support is often more valuable than manufacturing capability alone.

The rise of EUS-BD shows that gastrointestinal interventional devices are entering a more system-oriented stage of competition.

Future products will not compete only on individual functional components. They will increasingly compete on the performance and consistency of the entire catheter system.

EUS-BD is not merely a procedural trend. It is a signal that gastrointestinal intervention is undergoing a structural upgrade.

It does not mean that ERCP will be replaced. Rather, it shows that gastrointestinal intervention is moving from traditional access-based procedures toward more complex therapeutic endoscopic platforms.

In this process, multi-layer, multi-lumen, and composite structures will become essential foundations for advanced gastrointestinal interventional devices.

Multi-layer structures enable material performance allocation. Multi-lumen structures enable functional integration. Composite structures support pushability, kink resistance, torque response, and deployment stability.