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High-grade pediatric renal trauma: prognostic value of ureteral contrast
Phillip Kim, MD, Hansen T. Lui, MD, Lisa H. Kang, MD, Blythe Durbin-Johnson, PhD, Eric A. Kurzrock, MD.
UC Davis, Sacramento, CA, USA.

BackgroundAlthough non-operative management is encouraged for children with low-grade renal injury, there are no universally accepted guidelines for management of high-grade injury. We sought to determine if any patient variable, in particular the presence of contrast in the ureter on delayed images, was associated with intervention.
MethodsA retrospective review of pediatric patients presenting with grade IV or V renal injury between 2003 and 2021 at a Level 1 trauma center was performed. Patients with preexisting kidney disorders and those who did not have delayed phase CT during admission were excluded. Renal injury grade was verified and updated, if necessary, based upon the 2018 American Association for the Surgery of Trauma (AAST) injury scale. In addition, we determined if the injury was vascular or collecting system or both. We also collected data on patient demographics (age, gender, race/ethnicity), mechanism of injury (blunt vs penetrating), presence of any non-genitourinary injuries, Abbreviated Injury Scale (AIS) score and any renal intervention during admission and within 90 days of discharge such as urinary diversion with stent or nephrostomy tube or kidney surgery. 
Univariate and multivariable logistic regression analyses were performed, with estimates and their standard errors obtained using Firth's bias-reduced penalized likelihood method.
Results Seventy-five patients (mean age 12.4 years old) with Grade IV (n=53) or Grade V (n=22) injury were identified. Twenty-five patients (33%) had immediate renal intervention within 24 hours of admission, whereas 50 patients (66%) were observed. The mean age of observed patients was 11.2 years of age. Of the 50 patients observed, 15 (30%) had intervention [stent (n=9), nephrostomy tube (n=0), peri-renal drain (n=2), nephroureteral stent (n=1), embolization (n=1), open surgery (n=5)]. Delayed images on CT showed ureteral contrast was present in 44 (88%) of observed patients. Multivariable analysis adjusting for injury type (vascular and/or collecting system injury), mechanism, age and AIS score demonstrated that presence of contrast in the ureter is
associated with significantly lower odds of intervention, OR 0.06 [0.004-0.456, 95% CI, (P < 0.01)].
Conclusions After high-grade renal injury in children, the presence of contrast in the ureter on delayed CT imaging is associated with lower odds of procedural intervention. Despite the large size, this study is limited by the retrospective nature. After grade IV or V renal injury, presence of ureteral contrast may suggest a less severe renal collecting system defect and better odds that intervention can be avoided.

Table 1: Logistic Regression Analyses of Any Intervention by Patient and Imaging Characteristics
Variable Univariable Analyses Multivariable Analysis
Odds Ratio (95% CI) P-Value Odds Ratio (95% CI) P-Value
Contrast in Ureter: Yes vs. No0.083 (0.008, 0.479)0.004610.063 (0.004, 0.456)0.00497
Injury: Collecting System vs. Vascular0.783 (0.196, 3.346)0.7321.799 (0.301, 18.79)0.53860
Injury: Both vs. Vascular0.881 (0.15, 4.913)0.8851.452 (0.161, 18.104)0.74099
Injury Mechanism: Penetrating vs. Blunt1.386 (0.119, 11.384)0.765202.687 (0.197, 28.466)0.42004
Age (Years)1.013 (0.876, 1.181)0.8620.979 (0.827, 1.164)0.80182
Non-Renal AIS Score0.857 (0.594, 1.194)0.3680.858 (0.555, 1.252)0.43835
a Odds ratios for age and non-renal AIS score are the change in odds for a one-unit increase in age or AIS.


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