Challenges in the diagnosis of severe renal trauma in child: A case report and literature review

Abstract

INTRODUCTION:

To report the management and outcome of one case of pediatric patient sustaining high-grade blunt renal trauma. We present and discuss the clinical characteristics and radiologic features of the patient.

PATIENTS AND METHODS:

A 10 years old child was admitted for serious blunt renal trauma formed a huge urinoma in the right renal after injury gradually in 2018. We treated the patient with synchronous percutaneous nephrostomy drainage and retrograde ureteral catheterization. A retrospective review was performed of this case, including the clinical features, imaging studies and short-term follow-up. A literature review was also performed to highlight the principals of diagnosis and treatment of severe blunt renal trauma in children.

RESULTS:

After drainage, the symptoms of abdominal distension gradually disappeared, and the physical examination shows that the abdomen gradually reduced to normal. The huge urinoma was cured by synchronous drainge. No complications occurred in short-term follow-up.

COMMENTS:

The choice of surgical treatment is based on the degree and location of renal trauma. Grade IV injuries are a heterogeneous group and management should be tailored to the patient, especially among pediatric patients. Persistent urinary extravasation and/or symptomatic urinoma is a common complication of high-grade renal trauma, which will be amenable to ureteral stent placement or percutaneous drainage. For huge urinoma, synchronous percutaneous nephrostomy drainage and retrograde ureteral catheterization can relieve symptoms quickly.

Keywords

Renal Trauma Grade IV laceration Pediatric Urinoma Percutaneous drainage

1 Introduction

Renal trauma is present in to up 5% of all trauma cases [1]. It is most common in young males and has an overall population incidence of 4.9 per 100,000 [2]. The incidence of blunt renal injury in children is higher than that in adults. This is because the kidney in children is proportionately larger in size, more superficial, and has less protection from surrounding structures: i.e. less surrounding perirenal fat and the less ossification of the ribs [3]. Most blunt injuries result from motor vehicle accidents (MVAs), falls, sporting injuries, and assault [4]. Less commonly, sudden deceleration may result in an avulsion injury affecting the vascular structures of the hilum or the ureteropelvic junction (UPJ) [5]. Conservative management of high-grade (grade III-V based on the American Association for the Surgery of Trauma [AAST] grading system) blunt renal trauma in adults and children is becoming more common [6]. Ureteral stenting, percutaneous drainage and arterial embolization procedures may be used to drain symptomatic urinomas, treatment of life-threatening renal tract hemorrhage, and definitive ablation of traumatic arterio-venous (AV) renal fistulas including pseudoaneurysms.

Most urinomas after renal injury are asymptomatic and will spontaneously resolve in 76–87% of patients [7]. For symptomatic urinomas, percutaneous drain placement is the initial step followed by ureteral stent placement if drain outputs remain high in the clinical practice [8]. In this paper, we present one case. The child has serious blunt renal trauma, formed a huge urinoma in the right renal after injury gradually. Thus, the urinoma was drained by synchronous percutaneous nephrostomy under ultrasound-guided and retrograde ureteral catheterization using ureteroscope for urine drainage.

2 Case report

A 10-year-old male patient presented with right-sided flank abdominal pain and gross hematuria with alleged history of a fall from a bicycle. The patient was hospitalized to one hour after initial injury. On physical examination, the child was hemodynamically stable, had no abdominal masses and had right sided flank pain to percussion. A Foley catheter was placed but had no hematuria was present. A CT scan was obtained two hours after injury, which indicated right perinephric exudation (Fig. 1). Urine microscopy demonstrated microscopic hematuria. Platelet count at the time was 387*10⁹/L and hemoglobin concentration was 117 g/L. All other serum chemistry parameters were within normal limits. The patient was managed conservatively, i.e., bed rest, anti-infective, serial blood tests, regular observation and re-imaging. A repeat CT was obtained which demonstrated a large low-density mass in the right renal measuring 94×82 mm (Fig. 2a-b). The patient began to have anorexia with right flank swelling which prompted us to readmit the patient and obtain another CT abdomen which demonstrated that the right renal urinoma increased to 129×104 mm (Fig. 3a-b).

Fig.1

The CT scan of kidneys showed the renal parenchyma with mixed density and perinephric exudation (The injury day).

Fig.2a-b

Kidney CT scan show the urinoma which the size is 94*82 mm on the 14th days after injury).

Fig.3a-b

Kidney CT scan show the size of urinoma is 129*104 mm on the 46th days after injury).

The 56th days after injury, the patient was re-admission because of the marked enlargement of the right abdomen. The kidney computed tomography (CT) plain scan, and contrast-enhanced scan indicated the low-density mass in the right renal urinoma increase to 139mm*130 mm (Fig. 4a-b). Tables 1 lists the radiological features of the right kidney prior to intervention.

Fig.4a-b

The kidney computed tomography (CT) plain scan and contrast-enhanced scan indicated the size of urinoma 139mm*130 mm on the 56th days after injury.

Table 1

Radiologic features of right renal CT scan prior to drainage

Dates after injury	Computed tomography findings
Injury day	Mixed density perirenal exudation
14 days	The size of urinoma is 94 mm×82 mm.
46 days	The size of urinoma is 129 mm×104 mm.
56 days	The size of urinoma is 139 mm×130 mm.

3 Treatment

We treated the patient with percutaneous nephrostomy and retrograde ureteral stenting under general anesthesia. The creatinine (CR) level of the drainage fluid was 287μmol/l (normal serum creatinine values for men < 104μmol/l).

After drainage, the symptoms of abdominal distension gradually disappeared and his appetite increased, and physical examination revealed the abdomen was significantly reduced. However, the daily drainage of nephrostomy tube was maintained between 1500 ml to 2000 ml, the daily urinary volume excreted from the urethra is maintained at about 500 ml. The CT examination showed that partial DJ tube was located in the periphery of the kidney after the operation (Fig. 5). We performed fistula angiography after puncture and drainage (Fig. 6), confirmed the right renal parenchymal laceration: through corticomedullary into collecting system. Beginning on 2 August, the daily drainage of nephrostomy tube was reduced to about 750 ml, and increased urination of urethra up to about 1300 ml. On August 20, the daily drainage of nephrostomy tube was further reduced to about 100 ml. On August 25, nephrostomy without urinary drainage. On September 10, we removed the nephrostomy tube, and removed the DJ tube 2 weeks later by cystoscopy under general anesthesia.

Fig.5

The CT scan showed that partial DJ tube was located in the periphery of the kidney after drainage.

Fig.6

Fistula angiography show parenchymal laceration extending through collecting system.

A follow-up of more than one year after, the child had no complications of hypertension, hydronephrosis and urinary tract infections. The patient was followed up with laboratory examination including urine routine, urine culture and renal function examination are all within normal range, renal ultrasonography (3–6 months post-operatively), intravenous pyelography (IVP) (Fig. 7) and kidney CT plain scan and contrast-enhanced examination (Fig. 8) at 1 year postoperatively. The patient is still being followed.

Fig.7

IVP at 1 year postoperatively.

Fig.8

Kidney CT plain scan and contrast-enhanced examination at 1 year postoperatively.

4 Discussion

In pediatric abdominal trauma, the kidney is injured in approximately 10% of patients, and blunt trauma accounts for roughly 90% of these injuries [8]. The most commonly used classification system is that of the American Association for the Surgery of Trauma (AAST) [9]. It has been validated for its ability to predict morbidity and for the need for intervention [10, 11]. This remains the most useful of urological trauma classifications. However, the majority of Grade I-IV injuries are now managed conservatively and debate has centered around updating the classification of high-grade injuries i.e. identifying the injuries most likely to benefit from early angiographic embolization, repair or nephrectomy [12]. Signs suggestive of possible renal injury include: hematuria, flank ecchymosis, fractured ribs (10–12th), an abdominal mass, and abdominal tenderness or distension. Vital signs should be recorded throughout the initial assessment as they provide a reliable indication of situational urgency. In adult renal trauma, there are two most important indicators for significant injury are hematuria and hypotension (systolic blood pressure < 90 mm/Hg). However, blood pressure is not as reliable in pediatric populations as hypotension is a late manifestation of hypovolemia in children. The degree of hematuria does not clearly correlate with the degree of injury. It is important to be aware that not all cases of renal trauma will present with hematuria as some studies reported that only 12–44% of pediatric blunt renal trauma demonstrated gross hematuria [13 –16].

The main principles of management of pediatric patients after blunt renal injury includes renal preservation and minimization of morbidity [8]. Nonoperative management has been gaining generous support in hemodynamically stable grade I–III renal injuries [6 –8]. However, urinary extravasation and urinoma formation continue to be relative indications for a surgical intervention [17]. In stable patients, this means a period of bed rest, serial labs, regular observation and re-imaging as indicated. Patients with grade IV renal injuries are also most often treated conservatively, but the threshold for subsequent intervention is lower [18]. Wong et al. demonstrated that nonoperative management of nonvascular grade IV blunt renal trauma was successful in more than 80% of children [13]. Absolute indications for intervention in high grade renal trauma include unstable hemorrhage and/or ureteropelvic disruption [6 , 19–22]. Persistent urinary extravasation from an otherwise viable kidney after blunt trauma may respond to stent placement and/or percutaneous drainage [23].

Management of renal pelvic urine leak from renal trauma poses a specific debate as urinomas may be asymptomatic and most will resolve spontaneously [15]. The widely held hypothesis is that clots within the renal pelvis could migrate through the UPJ and ureter. Clots may impair drainage and spontaneous resolution of the collecting system injury, resulting in symptomatic or asymptomatic urinomas [22]. Urinary extravasation and urinoma continue to be relative indications for surgical exploration in some centers [17, 19].

The role of endourologic and percutaneous procedures for urine leak are not well examined in pediatric patients [13]. Currently, there are two treatment modalities for symptomatic urinomas in the setting of persistence of urinary extravasation. These include retrograde ureteral catheterization and percutaneous placement of a nephrostomy tube (Table 2) [22]. Though both methods are equally effective, placement of ureteral stents requires general anesthesia while nephrostomy tubes can be placed using bedside ultrasound and local anesthesia in older children [24, 25]. Nephrostomy tubes also provide a more accurate urine culture than a clean catch urine sample [26, 27]. Retrograde ureteral catheterization offers some advantages over percutaneous approaches as it avoids the risk of dislodging the tube. Furthermore, for pediatric patient populations, internal drainage is more cosmetically appealing. Disadvantages of nephrostomy tube include leakage, bleeding, and displacement of the tube [28]. Disadvantages of ureteral catheters and stents includes the necessity of removal and exchange often requiring general anesthesia. Secondly, the ureteral stents used in pediatrics are smaller and shorter than adults. Thirdly, the risk of perforating the ureter with stenting or part of the ureteral stent located around the kidney. Regardless of the disadvantages, Umbreit et al. advocates the use of retrograde ureteral catheterization as first line intervention for a symptomatic urinoma or a persistent urinary leak [8]. There is a controversy about the choice of two drainage methods for symptomatic urinomas or large urinomas (>4 cm) [29]. Two methods were used synchronous to alleviate symptoms quickly, particularly for individuals with very large urinomas that may lead to infection or abscess formation [8, 22]. However, if we managed the patient by percutaneous drainage or retrograde ureteral catheterization only, the result may be the same as we have managed.

Table 2
Comparison of percutaneous nephrostomy and retrograde ureteral catheterization

Percutaneous nephrostomy Retrograde ureteral catheterization

Anesthesia -Local anesthesia/General anesthesia -General anesthesia

Advantage -Quick -Noninvasive

-Effectively drain urine

-Offers unique bacteriological information

Disadvantage -Hemorrhage -Failed catheterization

-Urine leakage -Flare up bacteremia and septicemia

-Displacement of the tube -Perforating the ureter

-Place/Exchange/Removal DJ in operation room

Percutaneous nephrostomy	Retrograde ureteral catheterization
Anesthesia	-Local anesthesia/General anesthesia	-General anesthesia
Advantage	-Quick	-Noninvasive
	-Effectively drain urine
	-Offers unique bacteriological information
Disadvantage	-Hemorrhage	-Failed catheterization
	-Urine leakage	-Flare up bacteremia and septicemia
	-Displacement of the tube	-Perforating the ureter
		-Place/Exchange/Removal DJ in operation room

The conservative treatment of renal trauma can be considered as a series of nursing and management; a step-wise approach starting with conservative, followed by minimally invasive and/or surgical exploration if necessary, and the importance of escalation in treatment interventions should be emphasized. Primary conservative management is associated with a lower rate of nephrectomies, and no increase in immediate or long-term morbidity [19]. Absolute indications for intervention in high grade renal trauma include unstable hemorrhage and/or ureteropelvic disruption [6 , 20–22]. Persistent urinary extravasation from an otherwise viable kidney after blunt trauma often responds to stent placement and/or percutaneous drainage [23].

Management of renal pelvic urine leaks poses a specific debate as urinomas may be asymptomatic and most will resolve spontaneously [15]. The widely held hypothesis is that clots within the renal pelvis could migrate through the UPJ and ureter. Clots may impair drainage and spontaneous resolution of the collecting system injury, resulting in symptomatic or asymptomatic urinomas [22]. Urinary extravasation and urinoma continue to be relative indications for surgical exploration in some centers [17, 19].

Although the role of endourologic and percutaneous procedures have the potential to save functional renal parenchyma, decrease morbidity, and shorten the hospital course in adults, their roles are not well understood in pediatric population [13]. Currently, there are two ways to treat symptomatic urinomas and persistent urinary extravasation [22 –25]. The first is retrograde ureteral catheterization and the second is percutaneous placement of a nephrostomy tube (Table 2). Ureteral stenting needs to be performed in the operating room under general anesthesia, while nephrostomy can be performed by bedside ultrasonography under local anesthesia for older children or general anesthesia for young children. Nephrostomy tube may drain a urinoma more rapidly and cultures from a nephrostomy tube provide a higher microbiological detection rate than bladder urine cultures [26, 27]. However, its potential disadvantages are leakage, displacement of the tube, and bleeding, particularly in coagulopathic patients [28]. Retrograde ureteral catheterization offers some advantages over percutaneous approaches. It avoids the risk of dislodgement of the draining tube. Furthermore, for pediatric patient populations, internal drainage is more cosmetically appealing and is likely more acceptable. There are also two major disadvantages. Firstly, for most young children, both stent placement, removal and exchange require general anesthesia in operation room. Secondly, there is a risk of perforating the ureter with stenting or part of the ureteral stent located around the kidney.

Determining a time frame for failure of conservative management may help to establish appropriate follow-up intervals for those children most likely to require delayed intervention. Collecting system hematoma and urinoma size significantly predict failure of conservative management. Reese et al. investigated the timing and predictors for urinary drainage in children with conservatively managed AAST grade IV renal injury. The mean time to intervention was 11 days and the main predictors for intervention were collecting system hematoma(s) and urinoma (>4.0 cm) [22]. Prior studies have suggested a time range from 14 to 28 days to delayed intervention [20, 30]. For this patient, CT scan demonstrated formation of large urinoma (largest dimension 9.4 cm) (Fig. 2a, 2b) day 15 post injury. It is feasible then that in our case, intervention should have occurred sooner to prevent urinoma growth causing physical symptoms.

In this case, creatinine levels in peritoneal fluid was 287μmol/L (normal < 104 umol/L), but a few red blood cell (RBC). Clinically, the main manifestations were urinary leakage and formation of a huge urinoma gradually, no significant symptoms of massive hemorrhage. The X-ray images demonstrated rupture of the right renal pelvis in this case (Figs. 5, 6), so that grade IV renal injured only manifest as simple rupture of the renal pelvis in some cases. However, it is unclear how to grade the injuries to the renal pelvis in the AAST scale. Gregory P et al. classified that injury to the renal pelvis was grade IV injuries [29]. Based on the AAST scale, the grade IV should be involved on one of renal injuries: (i) Parenchymal laceration: through corticomedullary junction into, (ii) vascular: segmental renal artery or vein injury with contained hematoma, or partial vessel laceration, or vessel thrombosis. Clearly, it is necessary to consider the new grade or classification of renal injuries where laceration mainly located in the upper collecting system (Table 3).

Table 3

Differential diagnosis and treatment between Parenchymal lacerationand Collecting system laceration in the grade IV renal injuries

	Parenchymal laceration	Collecting system laceration
Causes	-Closed injury	-Open injury
	-Open injury	-Impact or Decelerated trauma
Injured regions	-Cortical laceration	-Collecting system
	-Parenchymal laceration	-Upper ureter
Symptoms	-Hemorrhage	-Hematuria
	-Hypotension
	-Shock
CT scan features	-Fractured kidney	-Urinary extravasation
		-Urinoma
Treatments	-Conservative management	-Conservative management (Urinoma < 4 cm)
	-Renal exploration	-Percutaneous nephrostomy (Urinomas > 4 cm)
	-Selective angioembolization	-Retrograde ureteral catheterization
Early complications	-Bleeding, infection, perinephric abscess, sepsis, urinary fistula, hypertension	-Urinary extravasation-Urinoma

Treatment of grade IV re nal injuries should be conducted according to the patient clinical condition. Mechanism of injury, vital signs stability, multiple injuries, and CT scan features are major factors that influence treatment decisions. Formation of urinoma particularly those rapidly enlarging, complicated with abdominal symptoms, and anorexia should raise concern. We treated our patient’s urinoma with percutaneous drainage and retrograde ureteral catheterization. However, we found the part of stent was located in the periphery of the kidney after operation (Fig. 5). This may be related to the following two factors. Firstly, the stent has a large loop circular. Secondly, the collecting system of the right kidney has a rupture. Therefore, if we have C-arm fluoroscopy in our operation room, we can adjust the position of the DJ tube during the operation, maybe take less time to heal the urinoma of our patient.

Early (<1 month) complications of renal trauma include bleeding, infection, perinephric abscess, sepsis, urinary fistula, urinary extravasation, and urinoma. Long-term complications include hydronephrosis, calculus formation, chronic pyelonephritis, hypertension, arteriovenous fistulae, hydronephrosis, and pseudo-aneurysms. Though it is rare, development of delayed hypertension after blunt renal trauma should also be concerning [31, 32]. The etiology for hypertension in these cases may be (i) external compression from peri-renal hematoma, (ii) renal scar formation, (iii) renal artery thrombosis, (iv) renal artery stenosis and AVF. Our patient has not reported sequelae to date (need the extent of follow up)

5 Conclusion

The AAST grading system is validated for predicting morbidity and the need for intervention in the adults but not for pediatric injuries. Graed IV injuries especially involving the collecting system or renal pelvis, are heterogenous and management should be individualized. Regardless of the grading system, grade IV injuries are a heterogeneous group and management should be tailored to the patient, especially among pediatric patients who present with unique anatomic differences.

A variety of radiologic techniques can be used to diagnose blunt renal trauma in children. If the patients are hemodynamically stable, CT scan and enhancement of kidney should be performed to identify grade of renal injury. Persistent urinary extravasation and/or symptomatic urinoma is common complication in high-grade renal trauma, and may be amenable to ureteral stent placement or percutaneous drainage, and thus urinomas should be treated actively once formed.

Conflict of interest

None of the contributing authors have any financial or personal relationships with people or organizations that could inappropriately influence this work.

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