Management of pediatric renal trauma with urinary extravasation: a retrospective study in a single clinical center

Introduction

Urinary extravasation is a common complication that affects 30% to 50% of adults with sustained high-grade renal trauma; however, the incidence of urinary extravasation in children is reported to vary widely (1). Most renal trauma can be cured by conservative treatment, especially for patients with renal trauma grade I–III according to the renal trauma classification established by the American Association for the Surgery of Trauma (AAST) (2). However, renal trauma with urinary extravasation or urinoma is classified as AAST grade IV, and there have been discussions about whether timely surgical intervention is needed. It has been reported that 91% of patients with adult renal trauma can be treated conservatively, while the proportion of patients with pediatric renal trauma requiring surgical intervention can range from 9% to 45% (3). Early detection and timely treatment of grade IV renal trauma requiring surgical intervention can alleviate children’s physical and mental suffering. In this study, the data of 19 children with grade IV renal trauma with urinary extravasation were retrospectively analyzed to explore the clinical characteristics, procedures and therapeutic results for pediatric renal trauma. The objective of this study is to provide clinical evidence for surgical intervention in children with grade IV renal trauma with urinary extravasation. We present this article in accordance with the STROBE reporting checklist (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-492/rc).

Methods

Study design and patients

Between December 2016 and December 2023, we identified 19 children with grade IV renal trauma with urinary extravasation at Children’s Hospital of Nanjing Medical University. Six of the 19 children were admitted to the emergency department, all with multiple injuries; 13 were admitted to the urology ward. This study was approved by the Ethics Committee of Children’s Hospital of Nanjing Medical University (Approval No. 202312132-1). Informed written consent was obtained from all the guardians of the children before the study. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013).

In this group, there were 19 patients—11 males and 8 females—aged 1 year 8 months to 10 years, with a mean age of 6.4 years; there were 11 injuries on the left side and 8 on the right side. According to the mechanism of injury, there were 6 cases of traffic injuries, 8 cases of fall injuries, 4 cases of injuries sustained while playing sports, and 1 case of a fall from height. There were 12 patients with isolated grade IV renal trauma and 7 patients with multiple injuries, including pulmonary contusion, adrenal hemorrhage, pneumothorax, cervical subluxation, pelvic fracture, rib fracture, craniocerebral trauma, and splenic injury. There were 5 cases of ureteropelvic junction (UPJ) rupture.

Diagnosis and treatment

In this group, 14 patients underwent plain computed tomography (CT), and 5 patients underwent enhanced delayed CT at the first visit. Among the 14 children with plain CT scans, 11 patients underwent CT-enhanced delayed scans 1 to 9 days after the initial CT examination, and the remaining 3 patients required magnetic resonance urography (MRU) or magnetic resonance cholangiopancreatography (MRCP) examination due to multiple injuries. Two ultrasound-guided perirenal cyst puncture and drainage procedures were performed at 12 and 36 days after injury; 7 cystoscopic double J tube drainage procedures were performed within 18 days after injury; 2 nephrostomy procedures were performed at 5 and 6 days after injury; 6 renal pelvic repair + pyeloureteroplasty procedures were performed within 5 days after injury; and 2 UPJ dissections plus renal calyceal ureteral anastomosis were performed at 6 and 9 days after injury.

Results

All the children were followed up from 2 to 61 months, with a median of 7.5 months. Two patients with perirenal urinoma underwent puncture drainage after postoperative ultrasonography and clamping of the drainage tube, which was removed without discomfort, and no urinary extravasation or hydronephrosis was observed on regular review [Figure 1 shows CT examination before (Figure 1A) and after (Figure 1B) urinoma puncture and drainage in one patient]. Seven patients underwent ureteral stent placement and drainage, and both the stent and drainage tube were removed under cystoscopy one month after surgery; there were no abnormalities, such as extravasation of urine or pyelonephritis, observed on regular follow-up ultrasound. After nephrostomy, one child experienced tube blockage and anastomosis tube displacement, hence the nephrostomy tube was replaced under general anesthesia, and then pyeloplasty was performed again. In another patient, a child who underwent nephrostomy had poor drainage, which was cured after repeated pyeloplasty and nephrostomy. Six children who underwent renal pelvis repair + pyeloureteroplasty recovered satisfactorily after surgery (Figure 2 shows CT examination of one patient with hydronephrosis rupture). One patient underwent postoperative ultrasound, which suggested 25 mm of hydronephrosis, but a repeat diuretic nephrogram suggested rapid drainage without an obvious obstruction curve. Two children who underwent calyceal ureteral anastomosis did not have obvious effusion on repeat ultrasound after surgery (Figure 3 shows a CT examination of one patient with UPJ disruption, Figure 3A: first CT scan, Figure 3B: CT scan at the ninth day). The details of the surgical interventions used are shown in Figure 4. Table 1 describes initial intervention time, success rate, complications and follow-up in the different surgical intervention.

Figure 1 Female, 7 years and 1 month old, fall injury resulting in rupture of the right kidney, contusion of the left kidney and contusion of the lungs. (A) CT suggests that a large amount of fluid has accumulated under the right renal pericardium and in the perinephric fat three days after the injury; (B) CT suggests that the perinephric fluid in the right kidney has been resorbed 25 days after perinephric urethrocystic puncture and drainage. CT, computed tomography.

Figure 2 Male, 5 years and 8 months old, fall injury resulting in left hydronephrosis rupture after trauma. CT suggests that the left renal silhouette is obviously enlarged, the renal pelvis and calyces are dilated, the left renal parenchyma is compressed bushy, the perinephric fat interstitial blurring, can see the watery density shadow encircling the left kidney, enhancement scan does not see abnormal strengthening, delayed scan can see the extravasation of the contrast medium. The left ureter was not clearly visible. CT, computed tomography.

Figure 3 Male, 2 years and 1 month old, left UPJ rupture, left lung contusion and rib fracture due to a traffic accident. (A) CT suggests a little exudation in the left perirenal space 1 day post-injury; (B) CT suggests a large encapsulated effusion visible in the perirenal space of the left kidney 9 days post-injury. CT, computed tomography; UPJ, ureteropelvic junction.

Figure 4 Details of the surgical intervention in 19 children with grade IV renal trauma with urinary extravasation. CT, computed tomography; MRU, magnetic resonance urography; MRCP, magnetic resonance cholangiopancreatography.

Discussion

Ultrasound is the imaging modality of choice for the assessment of blunt abdominal trauma in many health care settings, and further CT examination is required when high-grade renal trauma is detected on ultrasound or suspected clinically. Initial CT imaging should include both enhanced and delayed scans, not only to differentiate between urinary extravasation and hemorrhage but also to reduce the number of repeated CT examinations, thereby avoiding excessive radiation exposure (4,5). Therefore, delayed CT imaging is mandatory for proper assessment and staging of grade III or higher renal trauma (6). However, in children with abdominal trauma, especially in combination with other organ injuries or unstable vital signs, plain CT scans are often performed only at the initial visit. For these children, delayed CT scanning should be performed at a later date based on the first CT scanning examination, the ultrasound results reviewed during the course of the disease, and the child’s vital signs. Among the 19 patients in this group, only 5 underwent delayed CT scanning for the first time; 4 had renal pelvis rupture, and 1 had a UPJ fracture. In 11 patients, CT scanning was performed for the first time, and delayed CT scanning was performed again after 1–9 days (mean 3.7 days); 5 of these children with multiple injuries had unstable vital signs. Among these 11 patients, 6 had renal lacerations, 1 had renal pelvis rupture, 1 had renal calyx rupture, 1 had hydronephrosis with rupture, and 2 had UPJ rupture.

There is some debate as to when to perform imaging reassessment after conservative management of grade IV renal trauma. Repeat CT examination is mandatory for patients who show deterioration in their clinical condition or who do not undergo delayed scanning on the initial CT examination for various reasons. Several studies have shown that routine imaging of high-grade renal trauma may be unnecessary in the absence of any clinical signs or symptoms (7-9). In contrast, Overs et al. concluded that most patients with grade IV renal trauma develop symptoms or complications after 48–72 hours and therefore recommended systematic CT on day 4 or 5 to reassess the condition (10). In this study, five children with multiple injuries were admitted with unstable vital signs, only plain CT examination was performed, and delayed CT scanning was performed again 1–5 days after admission with stable vital signs. For children whose first examination was a CT scan, it is recommended that a delayed CT scan be performed after the vital signs have stabilized or when the urine extravasation worsens on ultrasound follow-up to avoid missing more severe UPJ rupture injuries. In this group, the child shown in Figure 3 was admitted to the hospital with only a minor left renal contusion and a small amount of perinephric exudate on CT plain scan, and the delayed CT scan on the 9th day after admission showed an area measuring 94 mm × 64 mm × 62 mm of encapsulated fluid under the perinephric pericardium. UPJ disruption was suggested by retrograde pyelogram in the emergency department, and there was no abdominal pain, vomiting or other discomfort during the course of the disease.

Initial conservative management of grade IV renal trauma has become the standard of care (6). Although grade IV and V renal trauma are associated with higher rates of surgical intervention and complications, initial observation is feasible if the patient is hemodynamically stable. The impact of the occurrence of urinary extravasation or urinoma on treatment remains a controversial issue. Asymptomatic urinary extravasation or urinoma resolve spontaneously in 90% of patients without surgical intervention (11). However, the optimal treatment for grade IV renal trauma in patients with stable vital signs in the presence of urinary extravasation is currently unclear. According to many of the available guidelines, more aggressive interventions is recommended for renal trauma in patients with combined collecting system injuries but the level of evidence is low. The severity of urinary extravasation requiring intervention is also currently undetermined, particularly in children. Ghani et al. suggested that the location of renal trauma affects the success or failure of conservative management, with anteromedial and medial contrast extravasation predicting an increased probability of surgical intervention, which is considered to be related to the area’s closer proximity to the peritoneum (6). The majority of urinoma are acute, but some children can present from 3 weeks to several months after injury. The relative indications for early surgical intervention include a persistent increase in the size of the urinoma, persistent fever for more than 48 hours, persistent low back pain, small bowel obstruction due to urinary extravasation, and isolated renal fragments within the urinoma (12,13). Reese et al. studied nonvascular grade IV blunt renal trauma in children and reported higher incidences of isolated renal fragments and interpolar extravasation in patients with failed conservative treatment. Their study demonstrated that urinoma greater than 4 cm in diameter were associated with an increased risk of failure of conservative treatment and the need for delayed intervention (14). Lee et al. reported that the need for a blood transfusion during the course of the disease as well as specific imaging features of the first CT examination, such as a renal fissure with the main site of renal fragmentation in the anterior medial aspect of the kidney, extravasation of intravascular contrast medium, and perirenal hematomas of more than 2.2 cm, could be useful predictors of urological intervention. For children with grade IV renal trauma with these predictive factors, imaging follow-up 4–5 days after trauma is recommended for early detection of associated complications and early intervention. Repeated imaging during hospitalization can be avoided if these factors are not observed on the first CT examination or during the clinical course (15). Bartley analyzed the CT manifestations of children with blunt renal trauma who had failed conservative treatment (16). Grade IV renal trauma with medial contrast extravasation was associated with the need for urological intervention, whereas delayed treatment may lead to higher complication rates and was associated with kidney loss. The specific site of renal trauma was not found to be associated with surgical intervention in this study due to the limited number of patients, and further validation with data from multicenter studies may be needed. In children with urinary extravasation due to renal parenchymal or renal pelvic laceration, conservative treatment was preferred by our group, and aggressive surgical intervention was indicated if extravasation or the size of urinoma increased progressively after conservative treatment. However, it is worth noting that posttraumatic rupture of hydronephrosis or UPJ disruption requires early aggressive surgical intervention.

There are more interventions for urinary extravasation, such as retrograde ureteral stenting, percutaneous nephrostomy tube placement, percutaneous perforation perinephric drainage, and laparoscopic or open repair. Grade IV renal trauma, especially involving the collecting system, is heterogeneous, and management should be individualized. Russell et al. recommended percutaneous puncture drainage followed by cystoscopic placement of ureteral stent tubes for persistent urinary extravasation (17). Retrograde ureteral placement and percutaneous nephrostomy are both equally effective, but general anesthesia is required for the placement of ureteral stent tubes; however, in older children, nephrostomy tubes can be placed by bedside ultrasound under local anesthesia. Retrograde ureteral placement has several advantages over percutaneous nephrostomy in that it avoids the risk of accidental catheter dislodgement and the tube is easier to care for. The disadvantages of percutaneous nephrostomy include leakage, bleeding and catheter migration. In contrast, the disadvantages of retrograde ureteral catheter placement include the need for removal and replacement of the catheter under general anesthesia, in addition to the risk of the ureteral stent being inserted around the kidney (18). In symptomatic urinoma or large urinoma (4 cm), the simultaneous use of both methods may provide rapid symptomatic relief, especially in patients with large urinoma that may lead to infection or abscess formation (19). In the early stage of this study, two children with urinary extravasation underwent perinephric urinoma puncture and drainage, and their postoperative recovery was good, but the drainage tube was difficult to care for, and the skin around the fistula was prone to ulceration and infection. In the later stage of the study, ureteral stenting was performed for all such children and achieved good clinical outcomes. For children with posttraumatic rupture of hydronephrosis or UPJ disruption, early and active exploration is recommended, the rupture can be repaired, and ureteral anastomosis of the renal pelvis or calyx can be performed at the same time. In this group, six patients underwent laparoscopic renal pelvis repair and pyeloureteroplasty, and two patients underwent calyceal ureteral anastomosis; all of these patients recovered well after the operation.

Limitations of this study include the inclusion of only a limited number of patients and a relatively short follow-up period, during which outcomes and complications were observed. It is necessary to evaluate the management of renal trauma with urinary extravasation with a larger sample size and longer follow-up time. Prospective studies are needed to draw further conclusions. The results of prospective studies will certainly be more convincing than the retrospective analysis in this study.

Conclusions

Overall, grade IV renal trauma with urinary extravasation requires active imaging evaluation, early delayed CT scanning is mandatory when vital signs are stable, and ultrasound or CT images need to be reviewed in a timely manner during the course of the disease according to the child’s clinical manifestations. Timely surgical interventions are needed for children with urinary extravasation or a persistent increase in the size of the urinoma, posttraumatic rupture of hydronephrosis, or a high degree of suspicion for UPJ dissecting injuries, and surgical interventions can be selected according to the specific circumstances of the child. Ureteral stenting, renal laceration repair with concomitant renal pelvis/calcaneal ureteral anastomosis can be chosen according to the specific conditions of the child.

Acknowledgments

We would like to express our sincere gratitude to the patients and their parents for participation in this study. Their patience and cooperation were instrumental to the success of this research. We also thank our colleagues in the Department of Radiology for their invaluable support and collaboration. Finally, we would like to thank our institution for providing the necessary resources and an enabling environment to conduct this research.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-492/rc

Data Sharing Statement: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-492/dss

Peer Review File: Available at https://tp.amegroups.com/article/view/10.21037/tp-2024-492/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tp.amegroups.com/article/view/10.21037/tp-2024-492/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study was approved by the Ethics Committee of Children’s Hospital of Nanjing Medical University (Approval No. 202312132-1). Informed written consent was obtained from all the guardians of the children before the study. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013).

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Keihani S, Anderson RE, Hotaling JM, et al. Diagnosis and management of urinary extravasation after high-grade renal trauma. Nat Rev Urol 2019;16:54-64. [Crossref] [PubMed]
2. Umbreit EC, Routh JC, Husmann DA. Nonoperative management of nonvascular grade IV blunt renal trauma in children: meta-analysis and systematic review. Urology 2009;74:579-82. [Crossref] [PubMed]
3. Hwang CK, Matta R, Woolstenhulme J, et al. Management of pediatric renal trauma: Results from the American Association for Surgery and Trauma Multi-Institutional Pediatric Acute Renal Trauma Study. J Trauma Acute Care Surg 2024;96:805-12. [Crossref] [PubMed]
4. Fernández-Ibieta M. Renal Trauma in Pediatrics: A Current Review. Urology 2018;113:171-8. [Crossref] [PubMed]
5. Gaither TW, Awad MA, Leva NV, et al. Missed Opportunities to Decrease Radiation Exposure in Children with Renal Trauma. J Urol 2018;199:552-7. [Crossref] [PubMed]
6. Ghani MOA, Snyder E, Xu MC, et al. Urine leaks in children sustaining blunt renal trauma. J Trauma Acute Care Surg 2022;93:376-84. [Crossref] [PubMed]
7. Lindner AK, Luger AK, Fritz J, et al. Do we need repeated CT imaging in uncomplicated blunt renal injuries? Experiences of a high-volume urological trauma centre. World J Emerg Surg 2022;17:38. [Crossref] [PubMed]
8. Schmidt J, Loftus CJ, Skokan A, et al. Routine repeat imaging may be avoidable for asymptomatic pediatric patients with renal trauma. J Pediatr Urol 2022;18:76.e1-8. [Crossref] [PubMed]
9. Loftus CJ, Hagedorn JC, Johnsen NV. Does routine repeat imaging for blunt high-grade renal trauma lead to unnecessary interventions? J Trauma Acute Care Surg 2021;90:143-7. [Crossref] [PubMed]
10. Overs C, Teklali Y, Boillot B, et al. Evaluation of the management of severe trauma kidney injury and long-term renal function in children. J Trauma Acute Care Surg 2018;84:951-5. [Crossref] [PubMed]
11. Singer G, Arneitz C, Tschauner S, et al. Trauma in pediatric urology. Semin Pediatr Surg 2021;30:151085. [Crossref] [PubMed]
12. Au JK, Tan X, Sidani M, et al. Imaging characteristics associated with failure of nonoperative management in high-grade pediatric blunt renal trauma. J Pediatr Urol 2016;12:294.e1-6. [Crossref] [PubMed]
13. Farr BJ, Armstrong LB, Barnett SC, et al. Variation in management of pediatric post-traumatic urine leaks. Eur J Trauma Emerg Surg 2022;48:173-8. [Crossref] [PubMed]
14. Reese JN, Fox JA, Cannon GM Jr, et al. Timing and predictors for urinary drainage in children with expectantly managed grade IV renal trauma. J Urol 2014;192:512-7. [Crossref] [PubMed]
15. Lee JN, Lim JK, Woo MJ, et al. Predictive factors for conservative treatment failure in grade IV pediatric blunt renal trauma. J Pediatr Urol 2016;12:93.e1-7. [Crossref] [PubMed]
16. Bartley JM, Santucci RA. Computed tomography findings in patients with pediatric blunt renal trauma in whom expectant (nonoperative) management failed. Urology 2012;80:1338-43. [Crossref] [PubMed]
17. Russell RS, Gomelsky A, McMahon DR, et al. Management of grade IV renal injury in children. J Urol 2001;166:1049-50.
18. Zhang Z, Zhang Y, Wang X, et al. Challenges in the diagnosis of severe renal trauma in child: A case report and literature review. J Xray Sci Technol 2020;28:357-67. [Crossref] [PubMed]
19. LeeVan E. Management of pediatric blunt renal trauma: A systematic review. J Trauma Acute Care Surg 2016;80:519-28. [Crossref] [PubMed]