What is the difference between covered and uncovered esophageal stents?

The main difference between covered and uncovered esophageal stents is that covered stents have a coating or membrane over the metal mesh, while uncovered stents do not. 

Key differences:

- Covering: Covered stents have a silicone, plastic, or fabric coating over metallic mesh. Uncovered stents have an exposed metallic mesh.

- Tissue ingrowth: Uncovered stents allow tissue ingrowth through the mesh which helps hold the stent in place. Covered stents prevent tissue ingrowth.

- Removability: Uncovered stents are more difficult to remove due to tissue ingrowth. Covered stents are more easily removable.

- Tumor/fistula ingrowth: Covered stents are better at preventing tumor or fistula ingrowth into the stent. Uncovered stents have gaps that allow ingrowth. 

- Stent migration: Uncovered stents have less risk of migration due to tissue ingrowth. Covered stents have a higher risk of migrating.

- Ease of insertion: Covered stents are more rigid and often require a larger delivery system, making insertion slightly more difficult. 

- Cost: Covered stents tend to be more expensive than uncovered ones. 

So in summary, covered stents prevent ingrowth but are less fixed in place, while uncovered stents allow ingrowth to help keep them in place but have gaps that allow ingrowth. The choice depends on the specific patient's situation.