Retrievable filters are fitted with a device (varying from model to model) that allows them to be easily snared and pulled back into a catheter and removed from the body, often through the jugular vein. Prior to 2004, filters that had been in the IVC for less than three weeks were considered suitable to attempt retrieval, as filters that have been in place longer might have been overgrown by cells from the IVC wall and there was an increased risk of IVC injury if the filter is dislodged. Newer designs, and developments in techniques mean that some filters can now be left in for prolonged periods and retrievals after a year are now being reported. This would include the ALN, Bard G2 and G2x, Option, Tulip and Celect filters.