What is a fully covered stent?

A fully covered stent is a type of esophageal stent that has a complete covering or membrane over the metallic mesh frame. 

The key features of fully covered stents include:

- Covering material: The stent is fully encapsulated in a covering, usually made from silicone, plastic (polyurethane), or fabric. This helps prevent tumor or tissue ingrowth through the stent.

- Removability: Fully covered stents are typically easier to remove than partially covered or uncovered stents, as tissue ingrowth is prevented by the covering.

- Migration risk: The covering can increase the risk of migration (stent moving from original placement site). Fully covered stents may have lower radial force and attachment to tissue.- Indications: Fully covered stents are often used to treat malignant esophageal strictures to maintain lumen patency. They can also treat esophageal perforations, fistulas, or leaks.

- Duration: Fully covered stents may be placed temporarily to relieve an obstruction before more definitive treatment. They are less suitable for permanent implantation.

- Limitations: The covering may block side branch openings (trachea, bronchi, esophageal diverticulum). Stent migration risk may require frequent adjustments or replacement. 

Overall, the complete covering on fully covered esophageal stents helps prevent tumor/tissue ingrowth and enables removability, but can increase migration risk. Careful patient selection and follow-up are important when implanting fully covered stents.