Overview
The WallFlex Biliary RX Stent System (Boston Scientific) is a self-expanding metal stent (SEMS) designed for percutaneous or endoscopic palliation of malignant biliary obstruction. Available in both uncovered and fully covered configurations, it is one of the most widely used biliary stents in interventional radiology and is a mainstay of hepatobiliary IR practice in the UK.
Indications
Malignant biliary obstruction (pancreatic head carcinoma, cholangiocarcinoma, metastatic hilar disease)
Palliative biliary drainage where surgical bypass is not appropriate
Benign biliary strictures (fully covered variant — off-label in some settings)
Post-surgical biliary complications
Available Configurations
| Type | Diameters (mm) | Lengths (mm) | Features |
|---|---|---|---|
| Uncovered | 8, 10 | 40, 60, 80 | Open mesh allows side-branch drainage |
| Partially Covered | 8, 10 | 40, 60, 80 | Silicone covering resists tumour ingrowth |
| Fully Covered | 8, 10 | 40, 60, 80 | Removable, prevents ingrowth, risk of migration |
Key Features
Platinol markers — radiopaque markers at both ends and mid-stent for precise fluoroscopic positioning
RX delivery system — rapid-exchange catheter compatible with 0.035" guidewire, 8 Fr sheath
Reconstrainable — can be partially deployed, repositioned, and then fully released for accurate placement
Flared ends — reduce migration risk and provide anchoring against the duct wall
Technique Tips
For percutaneous placement, ensure a mature transhepatic tract (usually 5–7 days of external drainage) before stent deployment.
Deploy the stent so that the distal end sits 1–2 cm into the duodenum to prevent obstruction of the ampulla.
Stent foreshortening occurs during deployment — account for approximately 30–40% shortening when selecting length.
For hilar tumours (Bismuth II–IV), consider a Y-stent or side-by-side configuration to drain both right and left hepatic ducts.
Covered stents are preferred for distal CBD obstruction. Use uncovered stents near the hilum to avoid occluding hepatic duct side branches.
Post-stent cholangiography should demonstrate free flow of contrast into the duodenum. If flow is sluggish, balloon-dilate within the stent.