A Case Series of Delayed Proximal Ureteral Strictures After Nephron-Sparing Treatment of Renal Masses.

Background: Delayed proximal ureteral stricture (DPUS) after nephron-sparing treatment (partial nephrectomy [PN] and image-guided percutaneous ablation) of renal masses is a rare complication that occurs because of an unrecognized injury to the proximal ureter and/or its associated vascular supply. We present a multi-institutional series of patients who developed DPUS after nephron-sparing treatment and review relevant tumor characteristics, timing of DPUS presentation, presenting symptoms, and outcome of stricture management. Case Presentation: Between 2000 and 2019, nine patients (five PN and four ablation) were found to have DPUS diagnosed at an average of 9 (6-119) months after PN and 5.5 (1-6) after ablation. Average tumor size was 4.5 (2.9-7.3) cm and 3.6 (3-4.1) cm for those treated with PN and ablation, respectively. Nephrometry score was 8.3 (6-11) and 6.5 (5-8), respectively. For resected tumors, all were located in the lower pole, but uniformity was not found as far as medial vs lateral (3 vs 2), anterior vs posterior (2 vs 2, 1 N/A), and right vs left (3 vs 2). For ablated tumors, all four tumors were right sided, anterior, medial, and lower pole. Initial signs and symptoms include sepsis (2), flank pain (5), and asymptomatic hydronephrosis (2). Concomitant urinoma (2) and retroperitoneal abscess (1) was found on imaging. Initial management included ureteral stenting (5) and percutaneous nephrostomy tube (4). Three underwent nephrectomy. Two had spontaneous resolution of DPUS after a course of ureteral stenting. Conclusion: Potential risk factors associated with DPUS after nephron-sparing treatment, including medial and lower pole tumors, and particularly right-sided anterior masses for ablation and higher complexity nephrometry score for PN. Recognition of delayed symptoms and imaging abnormalities in the surveillance period should cue clinical suspicion to DPUS.