Ureteral Stricture Occurrence after Transmural Ureteroscopic Ureteral Injury: A Previously Undocumented Concern

Purpose: Although the reported incidence of ureteral strictures following ureteroscopy (URS) is low (0.3%-3%), we hypothesize the risk may rise as the depth of ureteral injury increases. Materials and Methods: Between 2018 and 2022, 550 patients underwent URS for upper tract calculi; each of these patients had a postureteroscopic lesion scale (PULS) grading and follow-up imaging 3-6 months after a surgical procedure. Patients with preexisting strictures, or strictures formed at the site of an impacted stone, were excluded. Results: With a median follow-up of 23 months, de novo stricture rates for the 550 patients were 0.73% (4/550). More specifically, while strictures among patients with PULS 0 and 1 were minimal, 0% (0/235) and 0.48% (1/208), respectively. However, the stricture rate increased to 1.1% (1/92) for PULS 2 and jumped to 13.3% (2/15) among those patients with PULS 3 injuries. On a Firth penalized logistic regression analysis, we found that when urothelial splitting (i.e., PULS 2 or higher) or periureteral fat (i.e., a PULS 3 transmural injury) was visualized, the odds of developing a stricture were 13 and 40 times higher, respectively. Based on these findings, we sought to simplify the existing ureteral injury grades and improve ureteral stricture prognostication by creating a novel dichotomous injury scale. Conclusions: Iatrogenic ureteral stricture rates rose sharply when ureteral wall integrity was disrupted. This was most notable for a transmural injury, which resulted in a stricture rate of 13.3% (2/15 patients). Using a simplified two-stage scoring system (University of California, Irvine [UCI] 0, 1, or 2), clinicians may be better able to identify patients (i.e., UCI 2) at high risk for post-URS stricture formation.