What is the procedure for endoscopic stent placement in patients with obstructed bile or pancreatic ducts?

Endoscopic Stent Placement Procedure for Biliary and Pancreatic Duct Obstruction

Endoscopic stent placement is performed via ERCP (Endoscopic Retrograde Cholangiopancreatography) and involves advancing an endoscope to the duodenum, cannulating the ampulla, injecting contrast to visualize the biliary tree, and deploying a stent across the obstruction to restore bile flow.

Procedural Steps

1. Pre-procedure preparation:

   • Patient is typically placed under general anesthesia
   • Positioned in prone or left lateral position
   • Coagulation parameters should be checked (ERCP is preferred over percutaneous approaches in patients with coagulopathy - INR >2.0 or platelets <60K) 1

2. Endoscope advancement:

   • Side-viewing duodenoscope is advanced through the mouth, esophagus, and stomach into the second portion of the duodenum
   • The ampulla of Vater is identified and positioned in the field of view

3. Cannulation of the bile duct:

   • A catheter or sphincterotome with guidewire is used to cannulate the ampulla
   • Selective cannulation of the desired duct (biliary or pancreatic) is performed
   • Contrast is injected under fluoroscopy to visualize the ductal anatomy and identify the obstruction

4. Assessment of obstruction:

   • Location, length, and cause of obstruction are evaluated
   • Tissue samples may be obtained via brush cytology or biopsy if malignancy is suspected 1

5. Stent selection and placement:

   • Plastic stents:

     • Typically used for benign conditions, short-term drainage, or when expected survival is <3-4 months 2
     • Removable and less expensive but require replacement every 3-4 months due to occlusion 2

   • Self-expandable metallic stents (SEMS):

     • Used for malignant obstruction in patients with longer life expectancy
     • Longer patency but more expensive 2
     • Available as uncovered, partially covered, or fully covered

6. Stent deployment technique:

   • Guidewire is advanced across the stricture under fluoroscopic guidance
   • Stent delivery system is advanced over the guidewire
   • Stent is deployed across the stricture, with proximal end ideally positioned near the biliary hilar duct for distal malignant strictures 3
   • Fluoroscopic confirmation of proper positioning and drainage is obtained

7. Additional interventions (if needed):

   • Sphincterotomy may be performed to facilitate stent placement, though it's not always necessary for 10F plastic stent placement 4
   • Balloon dilation of tight strictures may be performed before stent placement
   • Stone extraction if choledocholithiasis is present 1

Special Considerations

• Failed conventional ERCP: Alternative approaches include:

  • EUS-guided biliary drainage - involves transduodenal puncture of the common bile duct with stent placement 5, 6
  • Percutaneous transhepatic biliary drainage (PTBD) - used when endoscopic approach fails 1

• Anatomical variations:

  • Previous gastroenteric anastomoses make conventional ERCP technically challenging 1
  • Periampullary diverticula may complicate cannulation

• Stent position optimization:

  • For distal malignant biliary strictures, placing the stent near the biliary hilar duct (about 2 cm from hilar duct) rather than just at the top of the obstruction results in significantly longer stent patency 3

Post-procedure Management

• Monitor for complications: pancreatitis, cholangitis, bleeding, and perforation (overall risk 4-5.2%) 1
• Plastic stents typically remain in place for 4-8 weeks for benign conditions like bile leaks 7
• Follow-up ERCP to confirm resolution of leaks before stent removal 7
• Stent exchange schedule depends on type: plastic stents every 3-4 months; metallic stents have longer patency 2

Complications and Troubleshooting

• Pancreatitis: Most common complication (2-5%)
• Cholangitis: Can occur if drainage is incomplete
• Bleeding: Associated with sphincterotomy (1-2%) 1
• Perforation: Rare but serious complication
• Stent occlusion: More common with plastic stents than metallic stents

For patients with coagulopathy or massive ascites, endoscopic approaches are preferred over percutaneous methods due to lower bleeding risk 1.