Evaluation of Optimal Stent Size after Antegrade Endopyelotomy: An Experimental Study in the Porcine Model

Abstract

To investigate the influence of two sizes of internal ureteral stents, 7 F and 12 F, on ureteropelvic junction (UPJ) healing after antegrade endopyelotomy. A right UPJ stricture was created in 10 pigs using an open surgical retroperitoneal approach. This model of obstruction consists of initially bridging the UPJ with a Terumo guide wire through an upper third ureterotomy and securing two 2.0 chronic gut ties around the UPJ over the guide wire and a 6 F ureteral catheter. The ureteral catheter is then withdrawn and the guide wire left in situ coiled up within the lumbar wall and fixed to the urogenital opening. Eight days later, each UPJ stricture was incised percutaneously using the invagination technique. Five pigs received a 7 F double-pigtail ureteral stent, while the remaining 5 pigs received a 12/7 F internal endopyelotomy stent. These stents were removed 1 week later. Retrograde ureteropyelography was performed at three months and the UPJ were examined grossly and harvested for histologic studies. One of the 5 pigs in each study group developed a recurrent stricture. The two groups were not statistically different in terms of histologic findings, although fibrosis of the muscle layer was more pronounced in the 12 F group. The use of a large caliber stent after experimental antegrade endopyelotomy does not provide any advantage over the use of a smaller easily positioned 7 F stent.