Effect of a metallic balloon-expanded stent on normal rabbit ureter.

Two-millimeter balloon-expanded Gianturco-Roubin coronary artery stents were placed in the 1-mm-diameter distal ureters of five normal rabbits. Retrograde pyelograms obtained immediately after stent placement showed no obstruction or extravasation of contrast material. Follow-up excretory urograms were obtained for each animal between 4 and 17 days, and autopsy was performed between 35 and 42 days. Findings at excretory urography and autopsy demonstrated severe obstruction at the level of the stent in each animal. Histologic examination of the resected ureter was performed. In four animals, the stent had penetrated into the wall of the ureter and a fibrous reaction had obliterated the lumen. In one animal, although the stent was still present within the lumen of the ureter, a fibrous reaction within the wall had destroyed the muscle layers and narrowed the lumen at the distal end of the stent. It is concluded that the 2-mm Gianturco-Roubin stent is unsuitable for placement in the 1-mm rabbit ureter.