How long do duodenal stents last?

The lifespan of a duodenal stent can vary quite a bit depending on the type of stent, the reason it was placed, and the specific circumstances of the patient. 

Some general timelines:

- Non-metallic stents: These are typically plastic stents that may last 3-6 months on average before needing to be replaced. They have higher risks of clogging or migrating out of position over time.

- Uncovered self-expanding metal stents: These metal mesh stents are designed to be permanent, but often only last about 6-12 months. Tissue can grow through the mesh over time, blocking the stent.

- Covered self-expanding metal stents: Covered in a thin membrane, these stents resist ingrowth and last longer - usually 1-2 years. However, they have a higher risk of migrating.

- Fully covered self-expanding metal stents: This newest generation of covered stents can last 2 years or more. The full membrane coverage prevents nearly all tissue ingrowth. 

Beyond the stent itself, the reason for placement also matters. Stents placed for temporary use, like after surgery, may only be needed for 4-6 weeks until the area heals. Stents for chronic problems like tumor narrowing may function for many months to years if needed. 

So in general, non-metallic stents tend to have the shortest duration, while modern fully covered self-expanding metal stents have the longest potential lifespan. Regular monitoring by a doctor is important to check on stent patency and function.