Small intestinal submucosa as a urethral coverage layer

Purpose: Urethrocutaneous fistula is the most common complication of hyposp adias surgery. Numerous techniques have been used to decrease the incidence of this complication and the use of biocompatible materials in surgery has expanded the options in difficult situations. We hypothesized that porcine small intestinal submucosa may be used as a coverage layer after urethral surgery. We evaluated the histological changes associated with small intest inal, submucosa when used as a coverage layer over the urethra in a rabbit model. Materials and Methods: We performed urethral surgery in 16 New Zealand Whit e rabbits divided into 4 animals each in groups 1-sham operation with penil e degloving only, 2-penile degloving and small intestinal submucosa patch p lacement, 3-urethrotomy without a patch and 4-urethrotomy with a small inte stinal submucosa patch. The graft, edges were marked with permanent suture at surgery for later identification. All rabbits were maintained for 6 week s before sacrifice. The urethra of each animal was then serially sectioned and examined histologically. Results: Histological examination of animals with an small intestinal submu cosa patch revealed a foreign body tissue reaction with an infiltrate of hi stiocytes, giant cells and lymphocytes in the area of graft placement. Ther e was no histological evidence of remaining small intestinal submucosa patc h in any sections. The urethral mucosa healed normally in all cases in whic h it was disrupted. There was no evidence of acute or chronic inflammation in any group 1 or 2 nonsmall intestinal submucosa animals and none in the a nimals with a small intestinal submucosa graft in areas other than the form er graft site. There were also no urethrocutaneous fistulas in any of the 8 rabbits that underwent urethrotomy. Conclusions: Small intestine submucosa presides an adequate coverage layer in the rabbit penis after urethrotomy. Histologically the foreign material did not alter normal healing of the urethral mucosa, although it did appear to cause an infiltration of histiocytes, giant cells and lymphocytes. Smal l intestinal submucosa has previously been studied as a scaffold on which t issue may be remodeled or may regenerate. Our study shes-vs that small inte stinal submucosa did not interfere with normal tissue healing in this anima l model. When used as a urethral coverage layer, it appears to provide extr a tissue between the urethra and skin. Small intestinal submucosa may poten tially decrease the incidence of urethrocutaneous fistula after urethral su rgery.