Figure. Contrast-enhanced delayed phase imaging of a 47-year-old female who sustained complete ureteral transection injury (American Association for the Surgery of Trauma grade 4) of the right ureteropelvic junction after motor vehicle vs pedestrian trauma. A, Contrast extravasation from the right ureteropelvic junction is seen. B, Contrast opacification of the distal left ureter is seen with no contrast opacification of the distal right ureter.

Ureteral injuries secondary to blunt mechanism external trauma are very rare and can present significant challenges related to diagnosis and management for the practicing urologist. Ureteral injuries represent 1%–2.5% of urological injuries from external trauma, with a small minority of these being due to blunt mechanisms.^1,2 The AUA Urotrauma Guidelines provide a guiding framework for acute evaluation and management, but the stakes can be high with such a rare condition.³ A variety of challenging clinical scenarios can yield uncertainty regarding the optimal tools for diagnosis, and clinicians are tasked with complex management decisions based upon limited existent outcomes data. Delay in diagnosis can yield adverse events ranging from complex retroperitoneal collections and infections to the need for nephrectomy.⁴ Contemporary data from the National Trauma Data Bank suggest prevalent use of minimally invasive ureteral stenting even in cases where the guidelines would recommend early surgical repair, highlighting continued uncertainty regarding how best to manage these rare injuries.⁵ We recently reported on our 15-year experience at a large regional level 1 trauma center with the diagnosis and acute management of blunt mechanism ureteral injuries, and the insights from this work can serve to better equip the urologist encountering these rare and difficult cases.⁶

At our institution, hemodynamically stable blunt trauma patients undergo cross-sectional CT urography (CTU) imaging according to AUA Urotrauma Guidelines (indications include gross hematuria, microscopic hematuria with systolic blood pressure <90 mm Hg, and mechanism suspicious for renal/ureteral injury). CTU imaging is used to differentiate American Association for the Surgery of Trauma (AAST) grade II-III partial ureteral transections (urinary contrast extravasation on delayed phase images with intralumenal contrast reconstitution distal to the injury site) from AAST grade IV-V complete transections (urinary contrast extravasation with no intralumenal opacification distal to the injury site), as illustrated in the Figure. In the case of unstable patients requiring emergent laparotomy, our practice is to defer complete ureteral diagnostic evaluation at the time of initial laparotomy in most cases (other than those injuries readily exposed and where intraoperative stabilization has been achieved), and to pursue diagnosis and grading with CTU early postoperatively or with retrograde fluoroscopic studies at patients’ second-look laparotomy within 24 to 48 hours. This approach is based on prior limited case series and surgeon experience indicating the limited sensitivity of direct retroperitoneal inspection for ureteral or ureteropelvic junction injuries.⁷

In our study, there were 18 patients with AAST grade II-V blunt ureteral injuries, including 1 patient with bilateral complete transection injuries (19 total ureteral injuries). Trauma mechanisms were uniformly related to road traffic accidents (motor vehicle collision, motorcycle crash, pedestrian vs automobile) or falls from height, and there were 10 partial and 9 complete transection injuries. Patients demonstrated severe global injury burden with a median Injury Severity Score of 34 and associated major nonurological organ injuries in over 90% of cases. Most injuries were localized to the ureteropelvic junction or proximal ureter, including 10/10 partial transection injuries and 8/9 complete transections. Cross-sectional imaging appeared to be a sensitive diagnostic modality for blunt ureteral injuries, correctly diagnosing and accurately grading 16/16 patients who underwent a CTU; the remaining 2 patients (1 with unilateral, 1 with bilateral injuries) were accurately diagnosed at second-look laparotomy without preceding cross-sectional delayed phase imaging.

Among 9 partial injury patients who survived to early definitive management, 7 were managed conservatively with either close observation or minimally invasive ureteral stent placement and 2 underwent open surgical repair. All 7 conservatively managed patients and 1/2 surgically managed patients had no evidence of obstruction at a median of 9 months of follow-up. Among 9 complete ureteral transections (7 patients with unilateral injury and 1 with bilateral injuries), all underwent early operative repair including 8 undergoing primary anastomotic repair (pyeloplasty, ureteroureterostomy, or ureteroneocystostomy) and 1 requiring nephrectomy due to hostile postinjury factors precluding reconstruction. Seven of 8 ureteral units undergoing anastomotic repair had no evidence of obstruction at a median of 32 months of follow-up.

These findings support the use of CTU as a sensitive diagnostic tool in cases of suspected blunt ureteral trauma, and further support its value in accurately grading injuries to guide management based on ureteral injury severity. We would advocate early minimally invasive retrograde drainage with ureteral stent placement in cases of confirmed partial thickness injury. In the case of a critically ill patient who cannot tolerate early intervention under general anesthesia, close observation with repeat cross-sectional delayed phase imaging can be obtained within 48-72 hours to evaluate for spontaneous resolution of urinary contrast extravasation; it is our opinion that the urologist should remain vigilant for persistent urine leak and should be ready to place a retrograde ureteral stent in such cases. Some patients may require additional early operative intervention where retroperitoneal exposure would not entail significant additional risk (such as second-look laparotomy), and in these cases we would still consider open repair of an exposed partial transection injury. Complete ureteral transections merit early primary reconstruction once patients are stabilized. Despite the prevalence of extremely high-energy trauma underlying blunt mechanism ureteral injuries, urologists can achieve a successful functional outcome for most patients through timely diagnosis, accurate injury grading, and early utilization of appropriate minimally invasive (in the case of AAST grade II-III partial transection) or open surgical (AAST grade IV-V complete transection) techniques.