Delayed-phase computed tomography in high-grade renal trauma: Increased interventions without improved outcomes and the predictive value of symptoms at follow-up

INTRODUCTION: Screening for urinary extravasation after high-grade renal trauma using delayed-phase computed tomography (DPCT) has been associated with increased urological intervention rates. We investigated the association of DPCT with urological intervention and major complication rates while analyzing the predictive value of clinical symptoms of urinary extravasation at follow-up DPCT. METHODS: This retrospective cohort study analyzed patients aged 18 to 89 years with American Association for the Surgery of Trauma grades III to V renal injuries at a level 1 trauma center from 2013 to 2023. Data were obtained from the institutional trauma registry and electronic medical records. Univariable and multivariable regressions assessed the association of DPCT with major complication and urological intervention rates. In a subgroup analysis of only follow-up DPCT, the sensitivity, specificity, positive predictive value, and negative predictive value of urinary extravasation signs and symptoms (leukocytosis, fever, flank pain, hematuria) were calculated. RESULTS: Of 234 patients, 101 (43.2%) underwent DPCT at any point during their hospital course. Baseline characteristics were similar between DPCT versus no DPCT, including injury grade (p = 0.13). Delayed-phase CT patients had higher rates of urological interventions compared with no DPCT (21.8% vs. 2.3%, p < 0.001) but similar complication rates (16.8% vs. 16.5%, p = 0.95). After multivariable regression, DPCT was not associated with major complications (odds ratio, 1.49; p = 0.33) but with increased odds of undergoing urological intervention (odds ratio, 15.22; p < 0.001). The presence of at least one symptom at follow-up DPCT had a sensitivity and NPV of 100% for urinary extravasation (p = 0.019). CONCLUSION: Delayed-phase CT was strongly associated with urological interventions for urinary extravasation but not associated with major complications after risk adjusted analyses, and all asymptomatic patients had negative follow-up DPCTs. While our results suggest potential overtreatment regarding urological interventions and follow-up imaging, further confirmative prospective studies are needed given our study's single-center retrospective limitations. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level IV.