Ureteral tissue expansion for bladder augmentation: a long-term prospective controlled trial in a porcine model

We recently described a technique that iatrogenically produces segmental megaureter while preserving renal function. In our initial report in 5 of 8 pigs that underwent this procedure bladder augmentation with the expanded ureter was successful. Throughout the expansion and reconstructive process renal function was preserved and all 5 animals that underwent augmentation had increased bladder capacity at sacrifice 1 month postoperatively. In the present study we evaluated the long-term durability and performance of the ureteral segment used for augmentation.

We performed a prospective, controlled, double armed study in 8 pigs, including 4 control animals that underwent subtotal cystectomy only (group 1) and 4 animals that underwent subtotal cystectomy followed by bladder augmentation using the expanded ureteral segment (group 2). End point measurements included cystography, and measurement of bladder capacity, serum creatinine and random bladder residual urine volumes. All cystograms were performed using passive filling conditions at a standard filling pressure of 32 cm. water.

Bladder capacity throughout the study revealed consistently higher volumes in group 2 than in group 1. In 3 of the 4 group 1 subjects vesicoureteral reflux developed compared to no reflux in group 2. Creatinine levels were elevated at sacrifice in 50% of the animals in group 1 compared to none in group 2. Random bladder residual urine was less than 150 cc in 3 of the 4 group 2 subjects.

Serial cystograms in pigs after ureteral augmentation suggest that the tissue does not contract with time. Animals that underwent ureteral augmentation had significantly greater bladder capacity than controls. Random bladder residual urine volume remained low throughout the study period. Ureteral tissue expansion for bladder augmentation appears to be feasible and durable in this animal model. In addition, it may be protective against the deleterious effects associated with small capacity bladders.