Use of single layer small intestinal submucosa for long segment ureteral replacement: a pilot study

PURPOSE: Previous studies have demonstrated successful use of small intestinal submucosa (SIS) as a tube for replacing short segment (11 mm) proximal ureteral defects. However, such small segment ureteral defects could be managed by resection re-anastomosis. We evaluated the use of 1-layer SIS as a tube for the replacement of long segment ureteral defects. MATERIALS AND METHODS: The ureters of 5 female mongrel dogs were accessed through a median laparotomy incision. A 4 cm segment of mid ureter was resected on the right side. The right ureteral segments were replaced by tubularized SIS segments using 6-zero polydioxanone interrupted sutures. Internal pigtail stents were left for 6 weeks. All animals were sacrificed at 12 weeks. Ureteral patency was assessed by excretory urography and magnetic resonance urography 7 and 12 weeks after the initial procedures. Inflammation and regeneration were assessed histologically. RESULTS: At 12 weeks all ureters on the experimental side were completely occluded with significant hydroureteronephrosis and the subsequent deterioration of kidney function. At autopsy there was failure to calibrate any of the experimental ureters with a 3Fr catheter. Although histologically urothelium and muscular cells had proliferated over the graft, they were embedded in an intense fibrotic and inflammatory process. CONCLUSIONS: Technically 1-layer SIS was easily modeled, providing the conditions for watertight anastomosis. The regeneration of urothelium and muscle was induced and supported by the graft. However, functional replacement was not successful. One-layer SIS is not a suitable material for replacing long segment (4 cm) ureteral defects.