Laparoscopic replacement of urinary tract segments using biodegradable materials in a large-animal model.
OBJECTIVE
We elected to evaluate laparoscopic segmental bladder and ureteral replacement with free biodegradable graft materials in a large-animal model.


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 laparoscopically replaced: by a stinted (6F double-J stent) tube graft made of acellular matrix (AMX) prepared from minipig ureters (MUMX) in 6 animals, acellular matrix prepared from domestic pig ureters (DUMX) in 3, and small-intestinal submucosa (SIS) in 6. In 3 control animals, the ureteral gap was bridged only by an indwelling stent. The stent was removed at 6 weeks, and retrograde 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 matrix prepared from minipig small bowel (MBMX) in 6 animals, and SIS in 6 animals. The bladder was closed primarily in 6 control animals. Bladder capacity 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 time was 147 (range 85-200) minutes. At 12 weeks, the bladder capacity was 60% of the preoperative capacity in the control group, 118% in the MBMX group, 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.
Division of Urologic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA.
A L
AL
Shalhav
A M
AM
Elbahnasy
E
E
Bercowsky
G
G
Kovacs
A
A
Brewer
K L
KL
Maxwell
E M
EM
McDougall
R V
RV
Clayman
D020341:Absorbable Implants; D000818:Animals; D003558:Cystoscopy; D005109:Extracellular Matrix; D005500:Follow-Up Studies; D007421:Intestine, Small; D010535:Laparoscopy; D013552:Swine; D013556:Swine, Miniature; D014513:Ureter / Q000166:cytology / Q000601:surgery*; D001743:Urinary Bladder / Q000166:cytology / Q000601:surgery; D014567:Urography; D013520:Urologic Surgical Procedures / Q000379:methods*; D019459:Urothelium / Q000166:cytology