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Stents: Nonvascular
Brandt C. Wible, MD; Ashraf Thabet, MD
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KEY FACTS

  • Terminology

    • Preprocedure

      • Procedure

        • Post Procedure

          TERMINOLOGY

          • Synonyms

            • Endoprosthesis
          • Definitions

            • Nonvascular stent: Catheter-mounted artificial conduit; placed in diseased biliary, enteral, tracheobronchial, or urinary structures for various indications
              • Resists luminal narrowing/occlusion caused by extrinsic compression, scarring, malignancy
              • Enhances integrity of luminal wall, promoting closure of fistula/leak
            • Self-expanding stent: Sheathed in retractable delivery system; spontaneously expands after sheath retraction
              • Used for many nonvascular stent applications
              • Stent is constrained/collapsed on delivery device
                • Radial force anchors stent as it expands
              • Most deploy distally to proximally
              • Self-expanding metallic stent (SEMS): Composed of various materials
                • Elgiloy
                  • Cobalt, nickel, and chromium alloy
                  • High radial force
                • Nitinol
                  • Nickel and titanium alloy
                  • Increased flexibility; helpful in angulated regions
                  • Lower radial force compared to other stents
                • Stainless steel
                • MR compatibility
                  • Most nitinol/Elgiloy stents may be imaged
                  • Check manufacturer datasheet
              • Self-expanding plastic stent (SEPS)
                • Much less commonly used than SEMS
                • Used in some tracheobronchial and esophageal applications
                  • Larger delivery system
                  • May be placed at endoscopy/bronchoscopy
                • e.g., Polyflex (Boston Scientific; Natick, MA)
                  • Removable covered stent
                  • Polyester and silicone construction
            • Balloon-mounted stent: Externally mounted on angioplasty balloon
              • Balloon inflation required to deploy stent
              • May be used in tracheobronchial applications
            • Covered stent: Fabric integrated into inner/outer aspect of metal stent to form impermeable barrier
              • Most common fabrics: Silicone, polyurethane, expanded polytetrafluoroethylene
              • More resistant to tumor ingrowth than noncovered
              • Reduces epithelialization of metal lattice
                • Higher risk of stent migration
              • Partially or fully covered
                • Uncovered proximal and distal ends
                  • Increases epithelial ingrowth
                  • Reduces risk of stent migration
                • Removal of fully covered stents may be possible
                  • WallFlex, esophageal stent (Boston Scientific; Natick, MA)
            • Location-specific stents
              • Plastic upper urinary tract stents: Nephroureteral, ureteral
                • Ureteral obstruction
                • Ureteral leak, allowing injured ureter to heal over stent "scaffolding"
              • Biliary
                • Biliary obstruction: Consider obstructive etiology and patient's life expectancy in stent choice
                  • Life expectancy < 1 year: Permanent stent
                  • Benign etiology: Retrievable stent (e.g., plastic, covered)
                • Biliary leak: Retrievable stent (typically plastic)
                  • Plastic biliary stents placed via endoscopy

          PREPROCEDURE

          • Indications

            • Getting Started

              • Stent Considerations

                PROCEDURE

                • Patient Position/Location

                  • Procedure Steps

                    • Findings and Reporting

                      • Alternative Procedures/Therapies

                        POST PROCEDURE

                        • Postprocedure Imaging

                          OUTCOMES

                          • Complications

                            • Expected Outcomes

                              Selected References

                              1. Nam HS et al: Current status of biliary metal stents. Clin Endosc. 49(2):124-30, 2016
                              2. Fiuk J et al: The use of internal stents in chronic ureteral obstruction. J Urol. 193(4):1092-100, 2015
                              3. Kaplan J et al: Enteral stents for the management of malignant colorectal obstruction. World J Gastroenterol. 20(37):13239-45, 2014
                              4. ASGE Technology Committee et al: enteral stents. Gastrointest Endosc. 74(3):455-64, 2011
                              5. Dumonceau JM et al: Biliary stents: models and methods for endoscopic stenting. Endoscopy. 43(7):617-26, 2011
                              6. Katsanos K et al: Stenting of the lower gastrointestinal tract: current status. Cardiovasc Intervent Radiol. 34(3):462-73, 2011
                              7. Katsanos K et al: Stenting of the upper gastrointestinal tract: current status. Cardiovasc Intervent Radiol. 33(4):690-705, 2010
                              8. Adamo R et al: Management of nephrostomy drains and ureteral stents. Tech Vasc Interv Radiol. 12(3):193-204, 2009
                              9. Adamo R et al: Percutaneous ureteral interventions. Tech Vasc Interv Radiol. 12(3):205-15, 2009
                              10. van Delden OM et al: Percutaneous drainage and stenting for palliation of malignant bile duct obstruction. Eur Radiol. 18(3):448-56, 2008
                              11. Therasse E et al: Balloon dilation and stent placement for esophageal lesions: indications, methods, and results. Radiographics. 23(1):89-105, 2003
                              12. Dyer RB et al: Percutaneous nephrostomy with extensions of the technique: step by step. Radiographics. 22(3):503-25, 2002
                              13. Morgan RA et al: Malignant biliary disease: percutaneous interventions. Tech Vasc Interv Radiol. 4(3):147-52, 2001
                              Related Anatomy
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                              Related Differential Diagnoses
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                              References
                              Tables

                              Tables

                              KEY FACTS

                              • Terminology

                                • Preprocedure

                                  • Procedure

                                    • Post Procedure

                                      TERMINOLOGY

                                      • Synonyms

                                        • Endoprosthesis
                                      • Definitions

                                        • Nonvascular stent: Catheter-mounted artificial conduit; placed in diseased biliary, enteral, tracheobronchial, or urinary structures for various indications
                                          • Resists luminal narrowing/occlusion caused by extrinsic compression, scarring, malignancy
                                          • Enhances integrity of luminal wall, promoting closure of fistula/leak
                                        • Self-expanding stent: Sheathed in retractable delivery system; spontaneously expands after sheath retraction
                                          • Used for many nonvascular stent applications
                                          • Stent is constrained/collapsed on delivery device
                                            • Radial force anchors stent as it expands
                                          • Most deploy distally to proximally
                                          • Self-expanding metallic stent (SEMS): Composed of various materials
                                            • Elgiloy
                                              • Cobalt, nickel, and chromium alloy
                                              • High radial force
                                            • Nitinol
                                              • Nickel and titanium alloy
                                              • Increased flexibility; helpful in angulated regions
                                              • Lower radial force compared to other stents
                                            • Stainless steel
                                            • MR compatibility
                                              • Most nitinol/Elgiloy stents may be imaged
                                              • Check manufacturer datasheet
                                          • Self-expanding plastic stent (SEPS)
                                            • Much less commonly used than SEMS
                                            • Used in some tracheobronchial and esophageal applications
                                              • Larger delivery system
                                              • May be placed at endoscopy/bronchoscopy
                                            • e.g., Polyflex (Boston Scientific; Natick, MA)
                                              • Removable covered stent
                                              • Polyester and silicone construction
                                        • Balloon-mounted stent: Externally mounted on angioplasty balloon
                                          • Balloon inflation required to deploy stent
                                          • May be used in tracheobronchial applications
                                        • Covered stent: Fabric integrated into inner/outer aspect of metal stent to form impermeable barrier
                                          • Most common fabrics: Silicone, polyurethane, expanded polytetrafluoroethylene
                                          • More resistant to tumor ingrowth than noncovered
                                          • Reduces epithelialization of metal lattice
                                            • Higher risk of stent migration
                                          • Partially or fully covered
                                            • Uncovered proximal and distal ends
                                              • Increases epithelial ingrowth
                                              • Reduces risk of stent migration
                                            • Removal of fully covered stents may be possible
                                              • WallFlex, esophageal stent (Boston Scientific; Natick, MA)
                                        • Location-specific stents
                                          • Plastic upper urinary tract stents: Nephroureteral, ureteral
                                            • Ureteral obstruction
                                            • Ureteral leak, allowing injured ureter to heal over stent "scaffolding"
                                          • Biliary
                                            • Biliary obstruction: Consider obstructive etiology and patient's life expectancy in stent choice
                                              • Life expectancy < 1 year: Permanent stent
                                              • Benign etiology: Retrievable stent (e.g., plastic, covered)
                                            • Biliary leak: Retrievable stent (typically plastic)
                                              • Plastic biliary stents placed via endoscopy

                                      PREPROCEDURE

                                      • Indications

                                        • Getting Started

                                          • Stent Considerations

                                            PROCEDURE

                                            • Patient Position/Location

                                              • Procedure Steps

                                                • Findings and Reporting

                                                  • Alternative Procedures/Therapies

                                                    POST PROCEDURE

                                                    • Postprocedure Imaging

                                                      OUTCOMES

                                                      • Complications

                                                        • Expected Outcomes

                                                          Selected References

                                                          1. Nam HS et al: Current status of biliary metal stents. Clin Endosc. 49(2):124-30, 2016
                                                          2. Fiuk J et al: The use of internal stents in chronic ureteral obstruction. J Urol. 193(4):1092-100, 2015
                                                          3. Kaplan J et al: Enteral stents for the management of malignant colorectal obstruction. World J Gastroenterol. 20(37):13239-45, 2014
                                                          4. ASGE Technology Committee et al: enteral stents. Gastrointest Endosc. 74(3):455-64, 2011
                                                          5. Dumonceau JM et al: Biliary stents: models and methods for endoscopic stenting. Endoscopy. 43(7):617-26, 2011
                                                          6. Katsanos K et al: Stenting of the lower gastrointestinal tract: current status. Cardiovasc Intervent Radiol. 34(3):462-73, 2011
                                                          7. Katsanos K et al: Stenting of the upper gastrointestinal tract: current status. Cardiovasc Intervent Radiol. 33(4):690-705, 2010
                                                          8. Adamo R et al: Management of nephrostomy drains and ureteral stents. Tech Vasc Interv Radiol. 12(3):193-204, 2009
                                                          9. Adamo R et al: Percutaneous ureteral interventions. Tech Vasc Interv Radiol. 12(3):205-15, 2009
                                                          10. van Delden OM et al: Percutaneous drainage and stenting for palliation of malignant bile duct obstruction. Eur Radiol. 18(3):448-56, 2008
                                                          11. Therasse E et al: Balloon dilation and stent placement for esophageal lesions: indications, methods, and results. Radiographics. 23(1):89-105, 2003
                                                          12. Dyer RB et al: Percutaneous nephrostomy with extensions of the technique: step by step. Radiographics. 22(3):503-25, 2002
                                                          13. Morgan RA et al: Malignant biliary disease: percutaneous interventions. Tech Vasc Interv Radiol. 4(3):147-52, 2001