Acute ureteral elongation in two animal models using a balloon expander

Repair of ureteral injuries and strictures often necessitates a major reconstructive procedure such as a psoas hitch, Boari flap, renal mobilization, ileal interposition, or autotransplantation. Tissue expanders have been used to elongate nerves and arteries. We examined the effects of acute ureteral elongation in two animal models.

In eight female rabbits, we exposed the left ureter through a midline incision and placed a Ruiz-Cohen balloon beneath the undermined portion. The expander was then inflated until the ureter was tightly stretched across it. After deflation, the expanded segment was measured in situ and compared with its original length. Follow-up urography was performed, and the tissue was harvested and examined by a pathologist. The same procedure was performed in five pigs; however, in these animals, a segment of ureter was excised, and a ureteroureterostomy was performed, after the acute expansion.

We were able to achieve acute elongation of the expanded ureteral segment. The mean elongation was 31.3% in the rabbits and 32.0% in the pigs. An intravenous urogram (IVU) 6 weeks after the elongation showed a functioning kidney and a patent ureter. Histologic examination of the ureter within 24 hours after the expansion revealed that all segments were viable, the luminal epithelium was intact, and the muscular layers appeared normal. At 6 weeks, the expanded segment showed mild inflammatory changes, but the overall morphology, size, and cytology findings were similar to those of a normal control.

Acute ureteral elongation using a tissue expander is a new method of increasing ureteral length. It may be useful to cover defects that would need major operations with greater morbidity.