Two Weeks Too Long: Optimal Duration for Ureteral Prestenting and Its Physiologic Effects on the Ureter in a Yorkshire-Landrace Pig Model.

INTRODUCTION: Prestenting of the ureter is commonly performed to allow for passive dilation and better access to the urinary system during subsequent procedures. There is no level 1 evidence on the duration of prestenting and EAU guidelines suggest a 1-2 weeks duration.

MATERIALS AND METHODS: Our primary aim is to investigate the optimal duration required for prestenting in a porcine model. Our secondary aim is to compare the ureteral wall compliance between the stented and the unstented ureters.

METHODS: Three female pigs between 40 and 50 kg were used. We modified a human protocol for performing intravenous pyelograms in our study to obtain ureteral measurements on days 0, 5, 7, and 14. Unilateral stenting on days 0, 5, and 7 was performed. On day 14, bilateral nephroureterectomy was performed, and ureteral compliance was measured in the stent and unstented ureter.

RESULTS: There were significant ureteral dilation between days 0 and 5 for all three pigs (p1  = 0.001, p2 ≤ 0.001 and p3  = 0.01). The rate of dilation appears to plateau after day 5 (p1  = 0.416, p2  = 0.344, and p3  = 0.774). Ureteral compliance in the stented ureter is better than in a nonstent ureter (p1  = 1.44 vs 0.13, p2  = 0.8 vs 0.04, p3  = 0.62 vs 0.2). An unexpected observation was the ureteral dilation and increased tortuosity in the unstented ureter in two of the three pigs (p1  = 0.152, p2  = 0.007).

CONCLUSION: Our results suggest that optimal prestenting may be achieved in 5 days in a porcine model. It can potentially form the basis to start randomized human trials.