What is the difference between fully covered and partially covered esophageal stents?

The main differences between fully covered and partially covered esophageal stents are:

- Coverage: Fully covered stents are completely coated with a material like silicone or polytetrafluoroethylene (PTFE). Partially covered stents have some areas that are uncovered or bare metal.

- Tissue ingrowth: Partially covered stents allow some tissue ingrowth into the bare metal sections which helps anchor the stent. Fully covered stents prevent tissue ingrowth which makes them easier to remove.

- Indications: Fully covered stents are often used for benign esophageal conditions like strictures since they are removable. Partially covered stents tend to be used for malignant conditions like esophageal cancer since tissue ingrowth helps keep them in place.

- Migration: Fully covered stents have a higher risk of migration (moving from the original placement site) since tissue doesn't grow into them. Partially covered stents have less risk of migration.

- Removability: Fully covered stents are more easily removable compared to partially covered stents where tissue has grown into the bare metal areas. 

- Patency: Partially covered stents may have better long-term patency (staying open) since tissue ingrowth helps keep the esophageal lumen open. 

So in summary, the main tradeoff is anchoring from tissue ingrowth with partially covered stents versus removability with fully covered stents. The choice depends on the specific patient's situation.