Can a greenfield filter ever have to be taken out ?

Yes: When the placement of a filter (ivc filter) is made, the decision is also made whether it would be a permanent filter or a retrievable filter is to be placed, depending on risks, life expectancy and need or cause of placement. The retrievable ones are removed later. And there are also attendant risks for filters such as called fracturing and it itself being flown into the right heart or lung.

Brand name: A Greenfield filter is a brand or type of IVC filter. Many physicians use the term to describe any IVC filters but there are many types similar to models of cars. Older greenfield filters had no mechanism for retrieval as so by definition are permanent and cannot be retrieved. Most contemporary vascular specialists will place a filter which allow retrieval in the future pending clinical issues.

Greenfield: There are retrievable filters which can be removed These are usually placed with the expectation to remove when situation resolves