Laparoscopic replacement of urinary tract segments using biodegradable materials in a large-animal model

Objective: We elected to evaluate laparoscopic segmental bladder and ureter al replacement with free biodegradable graft materials in a large-animal mo del. Materials and Methods: In 18 Yucatan minipigs, a 1.5- to 2.8-cm segment of the upper ureter was excised. In 15 study animals, the ureter was laparosco pically replaced: by a stinted (6F double-J stent) tube graft made of acell ular matrix (AMX) prepared from minipig ureters (MUMX) in 6 animals, acellu lar matrix prepared from domestic pig ureters (DUMX) in 3, and small-intest inal submucosa (SIS) in 6. In 3 control animals, the ureteral gap was bridg ed only by an indwelling stent, The stent was removed at 6 weeks, and retro grade ureteropyelography was performed preoperatively and at 8 and 12 weeks postoperatively, when animals were sacrificed. In 18 Yucatan minipigs, 3 x 3-cm bladder dome segments were laparoscopically replaced: by acellular ma trix prepared from minipig small bowel (MBMX) in 6 animals, and SIS in 6 an imals, The bladder was closed primarily in 6 control animals, Bladder capac ity was assessed preoperatively and at 6 and at 12 weeks, when the animals were sacrificed, Results: The average operating time for ureteral replacement was 187 (range 105-360) minutes. At 12 weeks, all animals had complete obstruction at the level of the replacement, with fibrosis +/- bone formation at the level of the stricture, For the bladder replacement groups, the average operating t ime was 147 (range 85-200) minutes. At 12 weeks, the bladder capacity was 6 0% of the preoperative capacity in the control group, 118% in the MBMX grou p, and 142% in the SIS group, Histologic examination showed regeneration of urothelium and some muscle with both MBMX and SIS, Conclusions: We were able to develop a reliable laparoscopic technique for both segmental ureteral and partial bladder replacement in a porcine model. With AMX and SIS replacement, regeneration of urothelium occurred in both ureter and bladder, However, functional replacement was successful only in the bladder.