Spontaneous ureteral stent fragmentation.

A series of spontaneous multiple fragmentations of 3 ureteral stents presenting with a variety of clinical features is reported. Physical analysis measuring the tensile mechanical properties was done of the retrieved fragments together with 2 new stents, as well as electron microscopy scanning of the retrieved fragments. This methodology in evaluating fractured stents is unique in its capability to determine the accelerated aging process of stent material and to our knowledge has not been reported previously in this context. The retrieved catheters were moderately incrusted. The tensile elongation (maximal elongation at break point), known to be a sensitive indicator of the aging process of plastic materials, was dramatically decreased in the retrieved stents. The fractures in all catheters retrieved as well as in the new stents were found to pass exclusively through the side holes. Fragmented catheters had a distinctive electron microscopic appearance and physical properties, which may be defined in a systematic manner and may contribute to further refinement of stent quality.