Superelastic guide-wire snare for removal of foreign bodies from the urinary tract.

A superelastic guide wire was used (after failure of other methods) as a loop snare to retrieve a foreign body from the ureter in three patients. In vitro comparison of the expansion capability of the superelastic guide wire and that of the standard retrieval wire showed that the superelastic wire forms larger loops within an elastic space. Also, because of less frictional resistance and its ability to be formed into stiffer loops, the superelastic wire resists kinking and is easier to manipulate than the standard wire.