Journal of Pediatric Surgery 50 (2015) 448–455
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Imaging assessment of renal injuries in children and adolescents: CT or ultrasound?☆ Eva Elisa Amerstorfer a, Axel Haberlik a,⁎, Michael Riccabona b a b
Department for Paediatric and Adolescent Surgery, Medical University of Graz, Austria Department for Radiology, Division of Paediatric Radiology, Medical University of Graz, Austria
a r t i c l e
i n f o
Article history: Received 30 January 2014 Received in revised form 2 July 2014 Accepted 3 July 2014 Key words: Renal injury Children and adolescents ALARA Diagnostics Ultrasound Management
a b s t r a c t Background: Since the introduction of the ALARA (“as low as reasonably achievable”) concept, ultrasound (US) has been progressively advocated for paediatric diagnostic imaging. This study aimed to analyse the role and accuracy of US in paediatric renal trauma. Methods: From 1999 to 2009, the tertiary-care-hospital database was retrospectively evaluated for renal trauma with regards to aetiology, type of injury, diagnostics, management and outcome. Results: Forty-seven patients (29 males, 18 females; median age = 14 years, range 1–17 years) were identified. US was initially applied in 45 patients with correct results in 86.6%. Computed tomography (CT) was performed in 16 patients in the acute trauma setting — complementary to US in 14 cases, with a diagnostic accuracy of 93%. Most renal injuries were grade I° (n = 30), followed by grade III° (n = 8), IV° (n = 5), and II°/V° (n = 2 each). All patients were initially managed conservatively and followed by US. Clinical deterioration necessitated surgery in four patients (2 nephrectomies, 1 partial nephrectomy, 1 urinoma drainage). The outcome was generally favourable with a renal preservation rate of 95%. Conclusion: With respect to the ALARA principle, US can be safely and reliably applied as the first-line diagnostic imaging technique and for follow-up for suspected traumatic paediatric renal injuries. © 2015 Elsevier Inc. All rights reserved.
Renal trauma is a rare injury type in children and adolescents but can lead to severe morbidity or even life threatening complications. Nowadays, renal injuries are predominantly managed conservatively due to diagnostic and therapeutic advances in paediatric traumatology. Although Computed Tomography (CT) can accurately identify and stage internal organ injuries [1] and thus is considered the first choice imaging method in trauma settings, its routine use has been discussed controversially in children [2–4]. Regardless that paediatric CT bears a high potential risk for inducing (fatal) cancer as published 10 years ago [5], its use has continuously increased over the last decade with a growth rate of almost 10% per year [4,6,7]. With arising awareness, the ALARA (“as low as reasonably achievable”) concept, introduced in 2001, has since been progressively advocated for paediatric diagnostic imaging [2,4]; consequently, ultrasonography (US) has been increasingly promoted as an alternative modality. With respect to the ALARA
principle, US has been suggested for imaging in mild to moderate paediatric renal trauma [8,9]. Hence, US has become the first choice imaging technique particularly for moderate trauma or trauma restricted to the kidney at our institution, and US is generally used for follow-up assessment. However, little evidence is available on its use and reliability particularly in paediatric (renal) trauma. Within the framework of radiation protection and with respect to the fact that it is paramount to maintain diagnostic accuracy and efficacy in paediatric trauma settings, we aimed to evaluate the role and diagnostic accuracy of US in paediatric blunt renal trauma by retrospectively analysing our experience, potentially revealing more evidence on the use of dedicated US as the first choice imaging method for initial assessment and for follow-up in mild or moderately traumatised children. 1. Material and methods
☆ Disclosure: The Division of Paediatric Radiology, Dept. of Radiology, Medical University Graz/Austria is in cooperation with Toshiba (Toshiba Medical Systems Cooperation, Japan) for paediatric Computed Tomography. Furthermore, it serves as reference centre for paediatric ultrasound for the companies GE healthcare (Milwaukee/USA) and Siemens (Erlangen/Germany). ⁎ Corresponding author at: Department for Paediatric and Adolescence Surgery, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz. Tel.: +43 316 385 13762; fax: +43 316 385 13775. E-mail address: [email protected] (A. Haberlik). http://dx.doi.org/10.1016/j.jpedsurg.2014.07.006 0022-3468/© 2015 Elsevier Inc. All rights reserved.
The hospital database was retrospectively reviewed for all paediatric and adolescent patients who were referred for renal injuries to our institution from 1999 to 2009. The Department for Paediatric and Adolescent Surgery and the Division of Paediatric Radiology at the Medical University of Graz, Austria, are a single tertiary care medical centre hospital covering a population of about 1 million. The retrieved data was analysed for age, gender, type of trauma, type of injury, associated injuries, diagnostic methods at
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presentation and follow-up, management, hospital stay and outcome. To grade renal injuries, the American Association for the Surgery of Trauma injury scale was applied [10]. Ethical approval was obtained from the local ethical committee of the Medical University of Graz, Austria (EK 25-474ex 12/13). The admitted children with suspected renal trauma were primarily evaluated by paediatric surgeons, who have been consistently trained in US and who in most cases performed the initial abdominal US study. The first US was always performed according to the FAST (Focused Assessment with Sonography for Trauma) concept; in stable patients it was complemented by a detailed study which also included a renal (amplitude-coded) colour Doppler Sonography ((a)CDS), mostly performed by paediatric radiologists. CT was performed in all cases of multiple and severe trauma, if US assessment was inconclusive, or for assessment of suspected additional injuries. The CT examination was conducted by paediatric radiologists. The age-adapted paediatric CT protocol [11] varied widely over time due to change in equipment and updated protocols addressing radiation protection issues. It always was performed as a helical CT scan, using 80–120 kV and 30–350 mA (with automated exposure control as soon as available). It always included at least a late parenchymal-pelvic phase after intravenous contrast administration by motor pump (200–350 mg iodine/ml, 1.5–2 ml/kg BW); in all multiple trauma cases an early arterial phase of the upper abdominal vessels (as part of the arterial neck, chest and abdominal imaging phase) and the abdomino-pelvic scan in the late parenchymal phase were acquired [12]. In selected cases only one delayed excretorypelvic phase was acquired for assessment of suspected collecting system injury; no split bolus techniques were used in this cohort. All CT studies were initially assessed by the radiologist on duty, and finally reported by an experienced staff paediatric radiologist. Depending on the severity of renal or associated injuries the patients were closely observed at either the normal ward or the intensive care unit following a standardised protocol which included bed rest, haemodynamic monitoring, serial laboratory evaluations (focusing on haemoglobin, haematocrit, white blood cell count, electrolytes, creatinine, blood urea nitrogen, and C-reactive protein), and documentation of presence and degree of haematuria. During follow-up, all patients were reassessed by US with (a)CDS after approximately 48 h, or earlier in case of clinical deterioration. A repeated CT or other imaging such as Magnet Resonance Imaging (MRI) was performed when US was inconclusive or showed severe renal injuries which prompted further information for treatment decisions, or when further imaging was required for associated injuries; in selected cases a focussed adapted intravenous urography (IVU) was used [9,12]. Renal Technetium (Tc) 99m Dimercaptosuccinic acid (DMSA) scintigraphy was conducted in order to assess the renal function in selected cases on follow up. Statistical evaluation was performed using SPSS19.0 (SPSS Inc., Chicago, IL, USA).
Forty-seven patients were treated for a renal injury over a period of 10 years in our department. There were 29 boys (62 %) and 18 girls (38%) with a male-to-female ratio of 1.6:1. The age of the injured patients ranged from 1 to 17 years, with a mean age of 12.7 years (median 14 years). The majority of renal injuries occurred in the age group of 13 to 18 years (n = 28, Fig. 1). Regarding the type of trauma, most renal injuries were due to sport accidents (n = 21), followed by vehicle accidents (n = 16) and falls (n = 10). In all patients, the mechanism of renal injury was a blunt abdominal trauma. The right kidney was slightly more often affected (n = 26) than the left kidney (n = 21). In none of the patients were both sides injured. Thirty-one renal injuries were associated with other injuries (Table 1), while isolated renal injuries occurred in only 31.9% of the patients. The majority of renal injuries were grade I injuries (n = 30, 29 renal contusions and 1 renal subcapsular haematoma); severe grade V injuries occurred in two cases (one grade Va and one grade Vb injury; Fig. 2). Twelve patients were admitted as multiple trauma patients, including also the two patients with grade V renal injuries. Besides two patients, who were immediately assessed by a CTexamination due to multiple trauma, all patients were primarily evaluated by US performed according to the FAST concept; this was complemented by (a)CDS in 38 patients (Fig. 3a–d). For additional
Fig. 1. Incidence of age group related traumatic injuries. Most renal injuries occurred in the age group of 13 to 18 years which is correlated to high velocity sport and vehicle accidents.
Fig. 2. Incidence of type related traumatic renal injuries. The majority of renal injuries were classified as type I renal injuries, followed by types III and IV renal injuries. Types II and V renal injuries occurred in only two patients each.
Table 1 Associated injuries. Associated injuries occurring in 31 patients N Abdomen
Thorax Head
Spinal Cord Spinal Column Extremities
Abdominal Wall Gastrointestinal Tract Liver Spleen Lung Ribcage Orofacial Region Brain Skull
Upper Limbs Lower Limbs Pectoral Girdle Pelvis
Skin Total Number of Associated Injuries Singular Associated Injuries (N of Patients = 8) Multiple Associated Injuries (N of Patients = 23; 12 clinically defined as patients with multiple trauma)
1 2 11 5 10 11 5 9 3 1 4 8 7 3 6 9 95 8 87
Seventy percent of renal injuries occurred with associated injuries which mainly affected the extremities and thorax. Associated abdominal injuries mainly affected the liver, which was injured in 11 patients. Twenty-three patients suffered from multiple injuries and were clinically classified as patients with multiple trauma in 12 cases.
2. Results
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Fig. 3. US with (a)CDS in renal trauma. (a) Transverse and (b) longitudinal section of right kidney from a flank access showing the grey scale appearance of the injured kidney, with a disrupted parenchymal echostructure in the area of the haematoma at the injury site, and a somewhat tumorous configuration. (c) CDS with spectral analysis of a peripheral intrarenal vessel demonstrating preserved perfusion of the residual non-affected parts of the same kidney as in Fig. 3a/b, with nicely visible intra-renal arterial and venous vessels in the upper and middle part of the injured kidney. Note the preserved diastolic flow and a relatively normal flow profile on the spectral analysis trace. (d) Power Doppler ((a)CDS) assessment nicely demonstrating the lack of perfusion in the injured lower section of the same kidney as in Fig. 3a–c.
diagnostic information, a CT was performed in 14 patients within the acute trauma setting (Table 2; Fig. 4). The US results correctly diagnosed the renal injury in 39 patients (86.6%). In those six false-negative US results for renal injuries, three had primarily only undergone a FAST scan (Table 3). In three patients, initial US + (a)CDS exams documented unknown congenital renal abnormalities which were unilateral hydronephrosis grade I in one and hydronephrosis grades I and II in a second patient, and an unilateral incomplete duplex kidney without further pathology in a third patient. All patients were sonographically reassessed during follow-up but did not require further diagnostic evaluation. No statistically significant difference could be evaluated between the accuracy of FAST and US + (a)CDS results for renal injuries in our study (Mann–Whitney-U test, p-value N0.05). Nor was there a
statistically significant difference between correct US results obtained from paediatric surgeons (n = 26/29), paediatric radiologists (n = 3/3) and radiologists of surrounding hospitals (n = 5/8); in 5 patients the US performing physician could retrospectively not be retrieved (Mann– Whitney-U test, p-value N 0.05). All initial CT examinations except in one case, where the CT exam – next to the FAST study – missed a small grade I renal injury which was diagnosed during follow-up by US + (a)CDS (see Table 3 case #3), were diagnostic for renal injuries (15/16; 93.7%). Haematuria was absent in 15 patients, 18 patients presented with microhaematuria and 14 had macrohaematuria (Table 4).
Table 2 CT performed additively to US within the acute trauma setting. Reason/Indication for CT Multiple trauma Assessment of potentially associated injuries based on US findings Severity of renal injuries on US with need for further diagnostic information Total number of patients examined by CT additively to US
Number 8 2 4 14
Fourteen patients were additively to US examined by CT within the acute trauma setting. Eight patients were further investigated by CT due to multiple trauma. In two patients, CT was indicated to assess potential associated injuries which were suspected by US showing signs of large lacerations of the spleen and left kidney in one patient, and because of inconclusive US results for associated abdominal injuries with signs for a right-sided renal laceration associated with severe pain in the right hemiabdomen in the second patient. In the latter patient, CT eventually excluded other abdominal organ injuries than a renal laceration grade IV. The severity of renal injuries in the primary US exam such as a huge perinephritic haematoma (n = 1), signs of renal infarction (n = 1), and large lacerations potentially affecting the collecting system (n = 2) prompted further diagnostic assessment by CT in 4 patients.
Fig. 4. Axial contrast enhanced CT section in a late parenchymal phase of a typical renal injury. The intra- and extra- (peri- and para-)renal portion of the haematoma (arrow) with disruption of the kidney contour at the laceration site is nicely visible, consistent with a grade III injury.
E.E. Amerstorfer et al. / Journal of Pediatric Surgery 50 (2015) 448–455 Table 3 Patients with primary false negative US results. Patients Primary study (n = 6) FAST
Primary study US + (a)CDS
Degree of Correct diagnosis renal injury establishment
#1
+ (conducted − in a surrounding hospital)
#2
+
−
Grade I
#3
+
−
Grade I
#4
−
+ (conducted Grade I in a surrounding hospital)
#5
−
+ (conducted Grade I in a surrounding hospital)
#6
−
+
Grade III
Grade I
The diagnosis of a rightsided grade III renal injury and liver laceration was established by a delayed CT scan performed due to a fluid collection in the Douglas and Morrison space, detected by followup US the next day. A grade I renal injury was diagnosed in a follow-up US with (a)CDS. While FAST was false negative for renal and other abdominal injuries, the CT exam, additionally performed because of multiple trauma, diagnosed a liver contusion but also missed a small grade I renal injury which was diagnosed during follow-up by US with (a)CDS. A grade I renal injury was diagnosed by a delayed abdominal CT which was performed due to persistent kidney pain on the left side, accompanied by microhaematuria. A grade I renal injury was diagnosed the following day in the follow-up US + (a)CDS study which also depicted a liver contusion. A grade I renal injury was diagnosed in the follow-up US. Due to increasing free abdominal fluids, a CT exam was eventually conducted and confirmed the sonographic diagnosis and excluded other parenchymal abdominal organ injuries.
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In general, all renal injuries were preferentially managed conservatively. Four patients (8.5%) required surgical treatment. Both patients with grade V renal injuries underwent nephrectomy; in one case because of a vascular pedicle avulsion diagnosed primarily by CT, and in the second case because of a shattered kidney injury with an uretero-pelvic avulsion, which was diagnosed by US and confirmed by adapted IVU documenting an absent excretion function (Fig. 5a and b). The third patient, re-staged by a repeated CT, underwent partial nephrectomy because of haemodynamic instability due to a grade IV injury, and the fourth patient required drainage of a posttraumatic urinoma after a grade IV injury which was suspected by US during follow-up and confirmed by MR-urography (Fig. 6a–d). Looking at the diagnostic accuracy of initially performed imaging modalities for associated abdominal organ injuries in our patient cohort, initial US correctly diagnosed only four of eleven hepatic injuries and suspected a liver injury in three cases (Table 5). Three hepatic injuries were missed in the initial US exam which was also
In six patients, the primary US findings were false negative for renal injuries. Half of these studies were performed according to the FAST concept, while the other three US studies were complemented by (a)CDS. Most missed renal injuries in the primary US exam were of minor pathology. All injuries were managed conservatively. In none of these patients, the delayed diagnosis of renal injury led to an adverse outcome.
Table 4 Haematuria related to the type of renal injury. Type of injury
Type Type Type Type Type
I II III IV V
Number of injuries (N = 47)
Macrohaematuria (N = 14)
Microhaematuria (N = 18)
Absence of haematuria (N = 15)
30 2 8 5 2
4 1 5 3 1
14 0 2 1 1
12 1 1 1 0
While microhaematuria was primarily present in patients with a grade I renal injury (14/30 patients), macrohaematuria rather occurred in patients with a more severe renal injury — although haematuria was absent in patients with one grade II, III, and IV renal injury each, confirming that haematuria cannot be seen as a reliable diagnostic marker for renal injuries.
Fig. 5. Adapted IVU in renal trauma. As CT was difficult to access at that time with an intensive care patient, and as renal perfusion and function needed to be assessed, this bed-side IVU was performed. (a) The early phase (5 min after contrast medium application) shows nice renal parenchymal enhancement and prompt excretion on the left side, but no renal contrast uptake on the right site (thus confirming the US suspicion of a devascularised kidney). (b) The late film (15 min after contrast application) confirms the early findings and furthermore demonstrates lack of evidence of any residual contrast excretion or extravasation at the right renal fossa.
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Fig. 6. Dynamic diuretic contrast enhanced MRU for early follow-up of renal trauma. This child with a shrunken left kidney had undergone injury to the hypertrophic right kidney. US follow-up suspected an urinoma and laboratory showed increasing creatinine values. Serial dynamic MR images (contrast-enhanced MRI with fast T1-weighted gradient echo sequences) show the normal renal perfusion and excretion of the kidneys (a), demark the lacerations site at the lower calix of the right kidney (b and d [rendered view]) and demonstrate nicely the significant contrast extravasation into the perirenal urinoma on late phase acquisitions (b and c).
Table 5 Diagnostics related to associated abdominal organ injuries in patients with renal trauma. Associated abdominal injury
Hepatic associated injuries Splenic associated injuries Gastrointestinal associated injuries
Primary US
Primary CT
Positive
Negative
Suspect
Positive
4 (all 4 US + (a)CDS) 2 (all 2 US + (a)CDS) 0
3 (2 FAST, 1 US + (a)CDS) 0 .. 2
3 (1 FAST, 2 US + (a)CDS) 2 (1 FAST, 1 US + (a)CDS) 0
1 (conducted due to multiple trauma) 1 (conducted due to multiple trauma) 0
Total number
11 5 2
Primary US correctly diagnosed 4/11 hepatic injuries and suspected a liver injury in 3 cases. Three hepatic injuries were missed in the initial US exam which was also false negative for renal injuries in these patients and diagnosed by CT (n = 2) or follow-up US + (a)CDS (n = 1). One liver grade III injury and one splenic rupture grade I were correctly diagnosed by CT, conducted primarily due to multiple trauma. Besides this splenic grade I injury, all other four splenic injuries were either correctly diagnosed (n = 2; once a grade II injury was confirmed by CT which was conducted due to unknown reasons 14 years ago and which would be nowadays only followed by US + (a)CDS or investigated by MRI at our institution) or suspected (n = 2) by the initial US exam and diagnosed by an additionally performed CT (conducted due to multiple trauma in the first and due to the suspect US findings in the other 3 patients). A CT was in total conducted in 8/11 patients with hepatic injuries (in 7 cases performed within the acute trauma setting because of multiple trauma and in 1 case performed delayed after a follow-up US exam displayed a fluid collection in the Douglas and Morrison space the following day after the initial FAST was negative for abdominal organ injuries) and 4/5 patients with splenic injuries, as described above. Associated gastrointestinal injuries were observed in two patients. One patient presented with a wide perineal laceration with a dorsal rectal skeletisation and suspect urethral injury. In this patient the primary US exam + (a)CDS displayed an unilateral grade I renal injury without signs of other intra-abdominal organ impairment. The patient underwent surgery to explore and treat the perineal wound and the suspect urethral injury (which could be excluded by intraoperative antegrade urethrography). The rectal injury was treated by a colostomy of the Colon descendens and Hartmann closure of the distal colon. A radiologically diagnosed instable pelvis fracture was stabilized during the same surgery. The second patient with an associated gastrointestinal injury presented with a wound of the abdominal wall. The FAST study showed a renal laceration on the right side and suspected an injury of the liver. An additively performed CT confirmed the grade IV renal injury and diagnosed a rupture of the Linea alba with herniation of small bowel and a grade II liver injury, next to a stable pedicle fracture of L5. The consecutive explorative surgery excluded a penetrating bowel or other abdominal organ injuries. Besides closure of the abdominal wall laceration, a jejunostomy was performed due to severe traumatic brain injury grade III (diagnosed in the additionally performed cerebral CT scan) for further enteral nourishment of the patient. The grade IV renal injury of this patient was treated conservatively.
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false negative for renal injuries in these patients and diagnosed by CT (n = 2) or follow-up US + (a)CDS (n = 1) (see Table 3, case #1, #3, and #5, respectively). Splenic injuries (n = 5) were primarily assessed by US in four patients and were correctly diagnosed in two and suspected in the other two patients by the initial US exam (Table 5). Noteworthy, all parenchymal liver and spleen injuries, which were of grades I–III in the majority of our patients, were managed conservatively. Only one patient with multiple trauma, suffering from a liver laceration grade IV associated with a splenic rupture grade III, and a grade III renal injury, required peritoneal drainage performed eight days after trauma due to breathing difficulties because of the intraabdominal blood accumulation. Of note, three CT exams conducted due to multiple trauma in the acute trauma setting unexpectedly diagnosed vertebral fractures next to other associated abdominal organ injuries. These vertebral fractures however were of stable character and did not require surgical intervention. All patients were followed by US; this included two to fourteen examinations per patient with a median of three US studies per patient. Ten patients underwent a delayed abdominal CT, which was mainly performed because of associated injuries (n = 9); in one case delayed CT was performed because of persisting macrohaematuria. Only one patient with a grade IV renal injury was re-staged by a repeated CT due to haemodynamic instability and eventually underwent a partial nephrectomy. Another patient underwent an abdominal plain film (kidney, ureter, bladder film — KUB) after undergoing a contrast-enhanced CT for assessment of urinary leakage, which revealed a grade III renal injury; this patient was managed conservatively. Delayed renal scintigraphy was conducted in six patients in order to assess renal function, and repeated in 2 patients during further follow-up. Indications for DMSA were severe injury, cotemporaneous UTI, and previous surgery (one patient was evaluated by DMSA after grade III renal injury at the site of a previously performed Anderson–Hynes pyeloplasty for obstruction of the uretero-pelvic junction). The median hospital stay was six days (range = 1–73 days). A longer hospital stay, however, was mainly required in multiple trauma patients because of associated injuries (range = 5–73 days, median = 17 days). All our patients were followed by US in order to document renal healing. Noteworthy, no late or routine follow-up CT was conducted for assessment of renal healing. The general outcome regarding renal injuries was favourable in the majority of our patients, with a renal preservation rate of 95.7%. 3. Discussion In general, renal injuries are rare injuries in childhood and account for about 2% of all traumatic injuries. Blunt abdominal trauma is the main cause for renal injuries in children and may affect the kidney in 10% to 20% [13–16]. Renal injuries are mainly associated with high velocity trauma due to vehicle or sports accidents [17]. The minority of paediatric renal injuries (which account for up to 10%) are attributed to penetrating abdominal trauma such as gunshot or stab injuries [17,18]. Children are more susceptible to renal injuries than adults because of the specific paediatric anatomic constitution which includes lack of perirenal fat, relative large size of the kidney compared to the rest of the body, and less ossified and more pliable thoracic cage [18,19]. In our cases, most renal injuries were of minor severity and mainly occurred in children older than 10 years and adolescents. However, the grade of injury increased with age and was associated with multiple trauma and additional injuries, mandating nephrectomy in both grade V renal injuries. Based on advances in diagnosis and management, a non-operative management was generally favoured in all patients, which was successful in 91.5% of our patients. Renal
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preservation was possible in 95.7%, which is comparable to renal salvage rates of other studies [17,20,21]. Since CT is – particularly in paediatric patients – associated with potential harmful side effects of ionizing radiation and thereby increased risk of (potentially fatal) cancer induction, the routine application of CT examinations for mild to moderate trauma is being reconsidered [12,22,23]. It has been recently speculated that about 10% to 30% of all CTs may be unnecessary as they are irrationally applied without profound justification, not adding any diagnostically relevant information or altering clinical management [24]. In paediatric renal trauma CT has been propagated as the first line diagnostic assessment tool for accurate staging and grading which directs an informed management decision [2,17,20,21,25]. CT has been internationally implemented as the standard of care because of its accuracy, its wide spread availability, its reliability and its ability to diagnose abdominal, retroperitoneal, skeletal, and pelvic urologic as well as non-urologic injuries [16,26]. In our patient cohort, however, US correctly depicted the renal injuries in ~87% of all initial examinations, which is comparable with the correct diagnostic percentage of primary CT examinations (93%). The time delay for those initial sonographically missed diagnoses did not alter the management or outcome nor caused any complications. Thereby – as part of a learning curve over time, also influenced by increasing radiation awareness – primary CT was only conducted in half of the patients (55%) and was limited to patients with multiple trauma or additional injuries, or inconclusive US findings. One initial CT performed in a patient with multiple trauma was even false negative for a renal grade I injury (renal contusion) which was eventually diagnosed sonographically during follow-up by (a)CDS. Nevertheless, the CT results of our patients, diagnosing not only renal but also associated abdominal organ or spinal column injuries, certainly helped the treating physicians in defining the management of these patients, partly by assuring the abdominal US findings. However, at our institution the CT examination would be nowadays, except in patients with multiple trauma or in case of immediate need for action due to acute deterioration of the clinical status, replaced by MRI, in case, that there is a need for additional imaging next to the US exam which should include (a)CDS. Concerning the diagnosis of underlying unknown congenital kidney malformations or even tumours, possibly prone to higher degree injuries in renal trauma, the initial US + (a)CDS examination documented unknown congenital kidney abnormalities of minor pathology in three patients of our patient cohort. These congenital pathologies were all diagnosed in patients with a renal contusion and were sonographically followed but did not require further diagnostic imaging. Based on these findings, we believe that possibly existing congenital abnormalities are not justifying the routine use of CT in renal traumas in all children and that US can reliably depict these disorders which may then still be examined by further diagnostic imaging if needed. Recently, repeated CT imaging has been recommended to re-assess all paediatric grades II to V renal injuries at 48 h if haemodynamically stable or earlier if required clinically, and in all grades IV to V renal injuries at 1 to 3 months to document adequate healing and function, possibly replaced by renography at that time [17,25]. At our institution, only one repeated CT was performed in one patient because of haemodynamic instability and due to a grade IV renal injury which eventually necessitated partial nephrectomy. All our patients were re-assessed by repeated US, significantly reducing radiation burden and without negative impact on management and outcome. A recent study generally stated renal US as the primary surveillance imaging method for patients with renal injury [27]. In contrast to our opinion, the same study, however, documented that an early US re-evaluation might be unnecessary as they saw US findings inconclusive without a repeat CT in two of their patients who required urinary drainage procedures [27]. Although US has been emphasised as a convenient, easily accessible, non-invasive, and inexpensive
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imaging method without ionizing radiation, its reliability depends on the examiner's skills, training, and anatomic and pathologic knowledge as well as the available US device/transducers. This may vary, and a skilled dedicated paediatric radiologist is not always available; furthermore US cannot reliably distinguish between extra-vasated urine, blood and other fluid. Thus the value of US has been discussed controversially for assessment of blunt abdominal trauma [2,3,28]. In children, however, the use of US with (a)CDS has been proposed as the first line imaging technique particularly with a mild or moderate trauma history, frequently establishing the initial diagnosis and potentially prompting CT as a complementary imaging method when needed [3,9,12,22]. In our patients, the detailed and dedicated US study, often including an (a)CDS assessment, being performed by well-trained paediatric surgeons and/or paediatric radiologists, has been sufficient and reliable for initial diagnosis and further management (also to decide on whether complementary imaging is necessary), and it enabled a favourable renal preservation rate of 95.7%. This approach resulted in a minor diagnostic delay in only six patients, but even there it did not alter the management or result in complications or an adverse outcome. In the future, contrastenhanced US may even further improve US potential allowing for a more robust sonographic renal injury assessment and thus enable a further reduction of radiating imaging [29–32]. Although we, based on our results, advocate to use US as a first line diagnostic imaging method in paediatric patients with renal trauma whenever possible, CT should always have its diagnostic value in hospitals where US is not frequently used or not available in order to enable conservative management of traumatized kidneys with higher degree lacerations.
Older imaging techniques such as IVU have been replaced by CT and sometimes MRI. Still, in some rare situations a focussed adapted IVU or just an abdominal plain film documenting the kidney, ureter and bladder (KUB) after contrast-enhanced CT for assessment of urinary leakage may be a valuable option; the latter approach helped to assess a grade III renal injury in one patient of our cohort. A focussed IVU was performed in one of our patients after initial US had depicted an absent renal perfusion, to confirm absent renal enhancement and secretion (Fig. 5a and b); nowadays this IVU would be replaced by immediate contrast-enhanced CT but – 10 years ago with only a dislocated CT scanner at that time at our institution – it seemed to be the most feasible available imaging technique. MRI is a little cumbersome in the acute setting for initial evaluation due to availability and handling, particularly with need for sedation or anaesthesia, as well as its longer duration. Contrast-enhanced MRI with MR-urography (MRU) however can be very helpful in assessing renal injuries as an add-on study or for followup, possibly replacing follow-up CTs. In one of our patients a traumatic urinoma was suspected by follow-up US after a grade IV renal injury; before deciding on treatment the suspicion was confirmed and topographically assessed by diuretic MR-urography with late acquisitions (Fig. 6a–d). The urinoma was, eventually, managed by percutaneous nephrostomy. Renal Tc99m DMSA scintigraphy is today reserved for follow-up examinations to evaluate renal function and scarring after severe injury as performed in six selected cases; in the future this also might be replaced by (functional) MR-urography [33]. All our patients were followed by US in order to document renal healing; no late routine follow-up CT for assessment of renal healing was conducted; in six selected cases, US was complemented by Tc99m DMSA scintigraphy.
Fig. 7. Imaging algorithm for paediatric patients with suspect renal trauma. The algorithm highlights US + (a)CDS as a key imaging modality in patients with mild to moderate renal trauma and as the main follow-up tool to monitor patients with a traumatic renal injury. A mild renal trauma is defined by a low energy injury to the kidney bed caused by coplanar falls on objects or hits by low-weight objects without visible signs of trauma, while a moderate renal trauma is clinically considered with the occurrence of visible trauma signs such as cuts, contusion marks or bruises — in context with moderate external forces impacting on the kidney area in the patient history. A severe renal trauma is defined by a rapid deceleration injury, fall from height, or direct flank injury caused by high external forces, also including penetrating injuries. FAST is recommended as the first investigation performed during clinical assessment of patients with severe or multiple trauma at the ER to provide quick information about the abdominal situation within the acute trauma setting. CT remains the next imaging step in all patients with multiple trauma unless unstable. Of note, US should be complemented by (a)CDS in all patients with mild to moderate renal trauma within the primary assessment and may be also performed in stable patients with severe renal trauma, if the direct impact was only to the kidney and if high quality US is quickly available. This algorithm has been modified based on the recommendation proposed by the ESPR Task uroradiology task force and ESUR paediatric working group (Riccabona et al. 2010 and 2011 [9,12]).
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Based on the findings of this retrospective study, we conclude that US (including (a)CDS) can be safely and reliably applied as a first line diagnostic imaging technique in renal injuries after mild to moderate paediatric blunt abdominal trauma. A contrast-enhanced CT should be reserved for patients with multiple or severe trauma, those with suspicion of associated injuries, or those with clinical or sonographic uncertainty — which potentially will be in part replaceable by MRI, particularly in stable patients. To illustrate the conclusions of our study, we established a diagnostic algorithm for patients with suspect renal trauma (Fig. 7). In our opinion, free fluid of unknown origin in the detailed US study is per se not indicating a CT examination in stable patients. With regards to our results and considering the ALARA principle, the above mentioned imaging algorithm appears safely applicable for assessment of paediatric renal injuries in the initial trauma setting and for follow-up, and advocates reduction of unnecessary radiation exposure to the paediatric patient. To achieve this, high level dedicated paediatric US must be made available for children 24 h a day throughout the year. References [1] Stanescu AL, Gross JA, Bittle M, et al. Imaging of blunt abdominal trauma. Semin Roentgenol 2006;41:196–208. [2] Eeg KR, Khoury AE, Halachmi S, et al. Single center experience with application of the ALARA concept to serial imaging studies after blunt renal trauma in children — is ultrasound enough? J Urol 2009;181:1834–40. [3] Lougué-Sorgho LC, Lambot K, Gorincour G. Kidney trauma in children: state of the art medical imaging. J Radiol 2006;87:275–83. [4] Shah NB, Platt SL. ALARA: is there a cause for alarm? Reducing radiation risks from computed tomography scanning in children. Curr Opin Pediatr 2008;20:243–7. [5] Brenner D, Elliston C, Hall E, et al. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001;176:289–96. [6] Brenner DJ, Hall EJ. Computed tomography — an increasing source of radiation exposure. N Engl J Med 2007;357:2277–84. [7] Brody AS, Frush DP, Huda W, et al. Radiation risk to children from computed tomography. Pediatrics 2007;120:677–82. [8] Pietrera P, Badachi Y, Liard A, et al. Ultrasound for initial evaluation of posttraumatic renal lesions in children. J Radiol 2001;82:833–8 [French]. [9] Riccabona M, Avni FE, Dacher JN, et al. ESPR uroradiology task force and ESUR paediatric working group: imaging and procedural recommendations in paediatric uroradiology, part III. Minutes of the ESPR uroradiology task force mini-symposium on intravenous urography, uro-CT and MR-urography in childhood. Pediatr Radiol 2010;40:1315–20. [10] Moore EE, Shackford SR, Pachter HL, et al. Organ injury scaling: spleen, liver, and kidney. J Trauma 1989;29:1664–6. [11] Damasio MB, Darge K, Riccabona M. Multidetector-CT in the paediatric urinary tract. Eur J Radiol 2013;82(7):1118–25.
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[12] Riccabona M, Avni F, Dacher JN, et al. ESPR uroradiology task force and ESUR paediatric working group: imaging recommendations in paediatric uroradiology, part IV. Minutes of the ESPR uroradiology task force mini-symposium on imaging in childhood renal hypertension and imaging of renal trauma in children. Pediatr Radiol 2011;41:939–44. [13] Rogers CG, Knight V, MacUra KJ, et al. High-grade renal injuries in children: is conservative management possible? Urology 2004;64:574–9. [14] Russell RS, Gomelsky A, McMahon DR, et al. Management of grade IV renal injury in children. J Urol 2001;166:1049–50. [15] Sarihan H, Abeş M. Nonoperative management of intra-abdominal bleeding due to blunt trauma in children: the risk of missed associated intestinal injuries. Pediatr Surg Int 1998;13:108–11. [16] Wessel LM, Scholz S, Jester I, et al. Management of kidney injuries in children with blunt abdominal trauma. J Pediatr Surg 2000;35:1326–30. [17] Buckley JC, McAninch JW. Pediatric renal injuries: management guidelines from a 25-year experience. J Urol 2004;172:687–90. [18] Brown SL, Elder JS, Spirnak JP. Are pediatric patients more susceptible to major renal injury from blunt trauma? A comparative study. J Urol 1998;160:138–40. [19] Kuzmarov IW, Morehouse DD, Gibson S. Blunt renal trauma in the pediatric population: a retrospective study. J Urol 1981;126:648–9. [20] Nance ML, Lutz N, Carr MC, et al. Blunt renal injuries in children can be managed nonoperatively: outcome in a consecutive series of patients. J Trauma 2004; 57:474–8. [21] Radmayr C, Oswald J, Muller E, et al. Blunt renal trauma in children: 26 years clinical experience in an alpine region. Eur Urol 2002;42:297–300. [22] Riccabona M. Abdominal emergencies in children — GU emergencies in children: kidney, ovary, testis. Insights Imaging 2011;2:S90 [A-339 (Book of Abstract, ECR 2011)]. [23] Pearce Mark S, Salotti Jane A, Little Mark P, et al. Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet 2012;380:499–505. [24] Ron E. Ionizing radiation and cancer risk: evidence from epidemiology. Pediatr Radiol 2002;32:232–7. [25] Buckley JC, McAninch JW. The diagnosis, management, and outcomes of pediatric renal injuries. Urol Clin N Am 2006;33:33–40. [26] Santucci RA, McAninch JM. Grade IV renal injuries: evaluation, treatment, and outcome. World J Surg 2001;25:1565–72. [27] Canon S, Recicar J, Head B, et al. The utility of initial and follow-up ultrasound reevaluation for blunt renal trauma in children and adolescents. J Pediatr Urol 2014 [Epub ahead of print, in press]. [28] McKenney KL, Nunet Jr DB, McKenney MG. Sonography as the primary screening technique for blunt abdominal trauma: experience with 899 patients. AJR Am J Roentgenol 1998;170:979–85. [29] Catalano O, Lobianco R, Sandomenico F, et al. Real-time, contrast-enhanced sonographic imaging in emergency radiology. Radiol Med 2004;108:454–69. [30] Riccabona M. Application of a second-generation US contrast agent in infants and children — a European questionnaire based survey. Pediatr Radiol 2012; 42:1471–80. [31] Thorelius L. Emergency real-time contrast-enhanced sonography for detection of solid organ injuries. Eur Radiol 2007;17:107–11. [32] Valentino M, Serra C, Zironi G, et al. Blunt abdominal trauma: emergency contrastenhanced sonography for detection of solid organ injuries. AJR Am J Roentgenol 2006;186:1361–7. [33] Grattan-Smith JD, Little SB, Jones RA. Evaluation of reflux nephropathy, pyelonephritis and renal dysplasia. Pediatr Radiol 2008;38:83–105.
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Journal of Pediatric Surgery journal homepage: www.elsevier.com/locate/jpedsurg
Imaging assessment of renal injuries in children and adolescents: CT or ultrasound?☆ Eva Elisa Amerstorfer a, Axel Haberlik a,⁎, Michael Riccabona b a b
Department for Paediatric and Adolescent Surgery, Medical University of Graz, Austria Department for Radiology, Division of Paediatric Radiology, Medical University of Graz, Austria
a r t i c l e
i n f o
Article history: Received 30 January 2014 Received in revised form 2 July 2014 Accepted 3 July 2014 Key words: Renal injury Children and adolescents ALARA Diagnostics Ultrasound Management
a b s t r a c t Background: Since the introduction of the ALARA (“as low as reasonably achievable”) concept, ultrasound (US) has been progressively advocated for paediatric diagnostic imaging. This study aimed to analyse the role and accuracy of US in paediatric renal trauma. Methods: From 1999 to 2009, the tertiary-care-hospital database was retrospectively evaluated for renal trauma with regards to aetiology, type of injury, diagnostics, management and outcome. Results: Forty-seven patients (29 males, 18 females; median age = 14 years, range 1–17 years) were identified. US was initially applied in 45 patients with correct results in 86.6%. Computed tomography (CT) was performed in 16 patients in the acute trauma setting — complementary to US in 14 cases, with a diagnostic accuracy of 93%. Most renal injuries were grade I° (n = 30), followed by grade III° (n = 8), IV° (n = 5), and II°/V° (n = 2 each). All patients were initially managed conservatively and followed by US. Clinical deterioration necessitated surgery in four patients (2 nephrectomies, 1 partial nephrectomy, 1 urinoma drainage). The outcome was generally favourable with a renal preservation rate of 95%. Conclusion: With respect to the ALARA principle, US can be safely and reliably applied as the first-line diagnostic imaging technique and for follow-up for suspected traumatic paediatric renal injuries. © 2015 Elsevier Inc. All rights reserved.
Renal trauma is a rare injury type in children and adolescents but can lead to severe morbidity or even life threatening complications. Nowadays, renal injuries are predominantly managed conservatively due to diagnostic and therapeutic advances in paediatric traumatology. Although Computed Tomography (CT) can accurately identify and stage internal organ injuries [1] and thus is considered the first choice imaging method in trauma settings, its routine use has been discussed controversially in children [2–4]. Regardless that paediatric CT bears a high potential risk for inducing (fatal) cancer as published 10 years ago [5], its use has continuously increased over the last decade with a growth rate of almost 10% per year [4,6,7]. With arising awareness, the ALARA (“as low as reasonably achievable”) concept, introduced in 2001, has since been progressively advocated for paediatric diagnostic imaging [2,4]; consequently, ultrasonography (US) has been increasingly promoted as an alternative modality. With respect to the ALARA
principle, US has been suggested for imaging in mild to moderate paediatric renal trauma [8,9]. Hence, US has become the first choice imaging technique particularly for moderate trauma or trauma restricted to the kidney at our institution, and US is generally used for follow-up assessment. However, little evidence is available on its use and reliability particularly in paediatric (renal) trauma. Within the framework of radiation protection and with respect to the fact that it is paramount to maintain diagnostic accuracy and efficacy in paediatric trauma settings, we aimed to evaluate the role and diagnostic accuracy of US in paediatric blunt renal trauma by retrospectively analysing our experience, potentially revealing more evidence on the use of dedicated US as the first choice imaging method for initial assessment and for follow-up in mild or moderately traumatised children. 1. Material and methods
☆ Disclosure: The Division of Paediatric Radiology, Dept. of Radiology, Medical University Graz/Austria is in cooperation with Toshiba (Toshiba Medical Systems Cooperation, Japan) for paediatric Computed Tomography. Furthermore, it serves as reference centre for paediatric ultrasound for the companies GE healthcare (Milwaukee/USA) and Siemens (Erlangen/Germany). ⁎ Corresponding author at: Department for Paediatric and Adolescence Surgery, Medical University of Graz, Auenbruggerplatz 34, 8036 Graz. Tel.: +43 316 385 13762; fax: +43 316 385 13775. E-mail address: [email protected] (A. Haberlik). http://dx.doi.org/10.1016/j.jpedsurg.2014.07.006 0022-3468/© 2015 Elsevier Inc. All rights reserved.
The hospital database was retrospectively reviewed for all paediatric and adolescent patients who were referred for renal injuries to our institution from 1999 to 2009. The Department for Paediatric and Adolescent Surgery and the Division of Paediatric Radiology at the Medical University of Graz, Austria, are a single tertiary care medical centre hospital covering a population of about 1 million. The retrieved data was analysed for age, gender, type of trauma, type of injury, associated injuries, diagnostic methods at
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presentation and follow-up, management, hospital stay and outcome. To grade renal injuries, the American Association for the Surgery of Trauma injury scale was applied [10]. Ethical approval was obtained from the local ethical committee of the Medical University of Graz, Austria (EK 25-474ex 12/13). The admitted children with suspected renal trauma were primarily evaluated by paediatric surgeons, who have been consistently trained in US and who in most cases performed the initial abdominal US study. The first US was always performed according to the FAST (Focused Assessment with Sonography for Trauma) concept; in stable patients it was complemented by a detailed study which also included a renal (amplitude-coded) colour Doppler Sonography ((a)CDS), mostly performed by paediatric radiologists. CT was performed in all cases of multiple and severe trauma, if US assessment was inconclusive, or for assessment of suspected additional injuries. The CT examination was conducted by paediatric radiologists. The age-adapted paediatric CT protocol [11] varied widely over time due to change in equipment and updated protocols addressing radiation protection issues. It always was performed as a helical CT scan, using 80–120 kV and 30–350 mA (with automated exposure control as soon as available). It always included at least a late parenchymal-pelvic phase after intravenous contrast administration by motor pump (200–350 mg iodine/ml, 1.5–2 ml/kg BW); in all multiple trauma cases an early arterial phase of the upper abdominal vessels (as part of the arterial neck, chest and abdominal imaging phase) and the abdomino-pelvic scan in the late parenchymal phase were acquired [12]. In selected cases only one delayed excretorypelvic phase was acquired for assessment of suspected collecting system injury; no split bolus techniques were used in this cohort. All CT studies were initially assessed by the radiologist on duty, and finally reported by an experienced staff paediatric radiologist. Depending on the severity of renal or associated injuries the patients were closely observed at either the normal ward or the intensive care unit following a standardised protocol which included bed rest, haemodynamic monitoring, serial laboratory evaluations (focusing on haemoglobin, haematocrit, white blood cell count, electrolytes, creatinine, blood urea nitrogen, and C-reactive protein), and documentation of presence and degree of haematuria. During follow-up, all patients were reassessed by US with (a)CDS after approximately 48 h, or earlier in case of clinical deterioration. A repeated CT or other imaging such as Magnet Resonance Imaging (MRI) was performed when US was inconclusive or showed severe renal injuries which prompted further information for treatment decisions, or when further imaging was required for associated injuries; in selected cases a focussed adapted intravenous urography (IVU) was used [9,12]. Renal Technetium (Tc) 99m Dimercaptosuccinic acid (DMSA) scintigraphy was conducted in order to assess the renal function in selected cases on follow up. Statistical evaluation was performed using SPSS19.0 (SPSS Inc., Chicago, IL, USA).
Forty-seven patients were treated for a renal injury over a period of 10 years in our department. There were 29 boys (62 %) and 18 girls (38%) with a male-to-female ratio of 1.6:1. The age of the injured patients ranged from 1 to 17 years, with a mean age of 12.7 years (median 14 years). The majority of renal injuries occurred in the age group of 13 to 18 years (n = 28, Fig. 1). Regarding the type of trauma, most renal injuries were due to sport accidents (n = 21), followed by vehicle accidents (n = 16) and falls (n = 10). In all patients, the mechanism of renal injury was a blunt abdominal trauma. The right kidney was slightly more often affected (n = 26) than the left kidney (n = 21). In none of the patients were both sides injured. Thirty-one renal injuries were associated with other injuries (Table 1), while isolated renal injuries occurred in only 31.9% of the patients. The majority of renal injuries were grade I injuries (n = 30, 29 renal contusions and 1 renal subcapsular haematoma); severe grade V injuries occurred in two cases (one grade Va and one grade Vb injury; Fig. 2). Twelve patients were admitted as multiple trauma patients, including also the two patients with grade V renal injuries. Besides two patients, who were immediately assessed by a CTexamination due to multiple trauma, all patients were primarily evaluated by US performed according to the FAST concept; this was complemented by (a)CDS in 38 patients (Fig. 3a–d). For additional
Fig. 1. Incidence of age group related traumatic injuries. Most renal injuries occurred in the age group of 13 to 18 years which is correlated to high velocity sport and vehicle accidents.
Fig. 2. Incidence of type related traumatic renal injuries. The majority of renal injuries were classified as type I renal injuries, followed by types III and IV renal injuries. Types II and V renal injuries occurred in only two patients each.
Table 1 Associated injuries. Associated injuries occurring in 31 patients N Abdomen
Thorax Head
Spinal Cord Spinal Column Extremities
Abdominal Wall Gastrointestinal Tract Liver Spleen Lung Ribcage Orofacial Region Brain Skull
Upper Limbs Lower Limbs Pectoral Girdle Pelvis
Skin Total Number of Associated Injuries Singular Associated Injuries (N of Patients = 8) Multiple Associated Injuries (N of Patients = 23; 12 clinically defined as patients with multiple trauma)
1 2 11 5 10 11 5 9 3 1 4 8 7 3 6 9 95 8 87
Seventy percent of renal injuries occurred with associated injuries which mainly affected the extremities and thorax. Associated abdominal injuries mainly affected the liver, which was injured in 11 patients. Twenty-three patients suffered from multiple injuries and were clinically classified as patients with multiple trauma in 12 cases.
2. Results
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Fig. 3. US with (a)CDS in renal trauma. (a) Transverse and (b) longitudinal section of right kidney from a flank access showing the grey scale appearance of the injured kidney, with a disrupted parenchymal echostructure in the area of the haematoma at the injury site, and a somewhat tumorous configuration. (c) CDS with spectral analysis of a peripheral intrarenal vessel demonstrating preserved perfusion of the residual non-affected parts of the same kidney as in Fig. 3a/b, with nicely visible intra-renal arterial and venous vessels in the upper and middle part of the injured kidney. Note the preserved diastolic flow and a relatively normal flow profile on the spectral analysis trace. (d) Power Doppler ((a)CDS) assessment nicely demonstrating the lack of perfusion in the injured lower section of the same kidney as in Fig. 3a–c.
diagnostic information, a CT was performed in 14 patients within the acute trauma setting (Table 2; Fig. 4). The US results correctly diagnosed the renal injury in 39 patients (86.6%). In those six false-negative US results for renal injuries, three had primarily only undergone a FAST scan (Table 3). In three patients, initial US + (a)CDS exams documented unknown congenital renal abnormalities which were unilateral hydronephrosis grade I in one and hydronephrosis grades I and II in a second patient, and an unilateral incomplete duplex kidney without further pathology in a third patient. All patients were sonographically reassessed during follow-up but did not require further diagnostic evaluation. No statistically significant difference could be evaluated between the accuracy of FAST and US + (a)CDS results for renal injuries in our study (Mann–Whitney-U test, p-value N0.05). Nor was there a
statistically significant difference between correct US results obtained from paediatric surgeons (n = 26/29), paediatric radiologists (n = 3/3) and radiologists of surrounding hospitals (n = 5/8); in 5 patients the US performing physician could retrospectively not be retrieved (Mann– Whitney-U test, p-value N 0.05). All initial CT examinations except in one case, where the CT exam – next to the FAST study – missed a small grade I renal injury which was diagnosed during follow-up by US + (a)CDS (see Table 3 case #3), were diagnostic for renal injuries (15/16; 93.7%). Haematuria was absent in 15 patients, 18 patients presented with microhaematuria and 14 had macrohaematuria (Table 4).
Table 2 CT performed additively to US within the acute trauma setting. Reason/Indication for CT Multiple trauma Assessment of potentially associated injuries based on US findings Severity of renal injuries on US with need for further diagnostic information Total number of patients examined by CT additively to US
Number 8 2 4 14
Fourteen patients were additively to US examined by CT within the acute trauma setting. Eight patients were further investigated by CT due to multiple trauma. In two patients, CT was indicated to assess potential associated injuries which were suspected by US showing signs of large lacerations of the spleen and left kidney in one patient, and because of inconclusive US results for associated abdominal injuries with signs for a right-sided renal laceration associated with severe pain in the right hemiabdomen in the second patient. In the latter patient, CT eventually excluded other abdominal organ injuries than a renal laceration grade IV. The severity of renal injuries in the primary US exam such as a huge perinephritic haematoma (n = 1), signs of renal infarction (n = 1), and large lacerations potentially affecting the collecting system (n = 2) prompted further diagnostic assessment by CT in 4 patients.
Fig. 4. Axial contrast enhanced CT section in a late parenchymal phase of a typical renal injury. The intra- and extra- (peri- and para-)renal portion of the haematoma (arrow) with disruption of the kidney contour at the laceration site is nicely visible, consistent with a grade III injury.
E.E. Amerstorfer et al. / Journal of Pediatric Surgery 50 (2015) 448–455 Table 3 Patients with primary false negative US results. Patients Primary study (n = 6) FAST
Primary study US + (a)CDS
Degree of Correct diagnosis renal injury establishment
#1
+ (conducted − in a surrounding hospital)
#2
+
−
Grade I
#3
+
−
Grade I
#4
−
+ (conducted Grade I in a surrounding hospital)
#5
−
+ (conducted Grade I in a surrounding hospital)
#6
−
+
Grade III
Grade I
The diagnosis of a rightsided grade III renal injury and liver laceration was established by a delayed CT scan performed due to a fluid collection in the Douglas and Morrison space, detected by followup US the next day. A grade I renal injury was diagnosed in a follow-up US with (a)CDS. While FAST was false negative for renal and other abdominal injuries, the CT exam, additionally performed because of multiple trauma, diagnosed a liver contusion but also missed a small grade I renal injury which was diagnosed during follow-up by US with (a)CDS. A grade I renal injury was diagnosed by a delayed abdominal CT which was performed due to persistent kidney pain on the left side, accompanied by microhaematuria. A grade I renal injury was diagnosed the following day in the follow-up US + (a)CDS study which also depicted a liver contusion. A grade I renal injury was diagnosed in the follow-up US. Due to increasing free abdominal fluids, a CT exam was eventually conducted and confirmed the sonographic diagnosis and excluded other parenchymal abdominal organ injuries.
451
In general, all renal injuries were preferentially managed conservatively. Four patients (8.5%) required surgical treatment. Both patients with grade V renal injuries underwent nephrectomy; in one case because of a vascular pedicle avulsion diagnosed primarily by CT, and in the second case because of a shattered kidney injury with an uretero-pelvic avulsion, which was diagnosed by US and confirmed by adapted IVU documenting an absent excretion function (Fig. 5a and b). The third patient, re-staged by a repeated CT, underwent partial nephrectomy because of haemodynamic instability due to a grade IV injury, and the fourth patient required drainage of a posttraumatic urinoma after a grade IV injury which was suspected by US during follow-up and confirmed by MR-urography (Fig. 6a–d). Looking at the diagnostic accuracy of initially performed imaging modalities for associated abdominal organ injuries in our patient cohort, initial US correctly diagnosed only four of eleven hepatic injuries and suspected a liver injury in three cases (Table 5). Three hepatic injuries were missed in the initial US exam which was also
In six patients, the primary US findings were false negative for renal injuries. Half of these studies were performed according to the FAST concept, while the other three US studies were complemented by (a)CDS. Most missed renal injuries in the primary US exam were of minor pathology. All injuries were managed conservatively. In none of these patients, the delayed diagnosis of renal injury led to an adverse outcome.
Table 4 Haematuria related to the type of renal injury. Type of injury
Type Type Type Type Type
I II III IV V
Number of injuries (N = 47)
Macrohaematuria (N = 14)
Microhaematuria (N = 18)
Absence of haematuria (N = 15)
30 2 8 5 2
4 1 5 3 1
14 0 2 1 1
12 1 1 1 0
While microhaematuria was primarily present in patients with a grade I renal injury (14/30 patients), macrohaematuria rather occurred in patients with a more severe renal injury — although haematuria was absent in patients with one grade II, III, and IV renal injury each, confirming that haematuria cannot be seen as a reliable diagnostic marker for renal injuries.
Fig. 5. Adapted IVU in renal trauma. As CT was difficult to access at that time with an intensive care patient, and as renal perfusion and function needed to be assessed, this bed-side IVU was performed. (a) The early phase (5 min after contrast medium application) shows nice renal parenchymal enhancement and prompt excretion on the left side, but no renal contrast uptake on the right site (thus confirming the US suspicion of a devascularised kidney). (b) The late film (15 min after contrast application) confirms the early findings and furthermore demonstrates lack of evidence of any residual contrast excretion or extravasation at the right renal fossa.
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Fig. 6. Dynamic diuretic contrast enhanced MRU for early follow-up of renal trauma. This child with a shrunken left kidney had undergone injury to the hypertrophic right kidney. US follow-up suspected an urinoma and laboratory showed increasing creatinine values. Serial dynamic MR images (contrast-enhanced MRI with fast T1-weighted gradient echo sequences) show the normal renal perfusion and excretion of the kidneys (a), demark the lacerations site at the lower calix of the right kidney (b and d [rendered view]) and demonstrate nicely the significant contrast extravasation into the perirenal urinoma on late phase acquisitions (b and c).
Table 5 Diagnostics related to associated abdominal organ injuries in patients with renal trauma. Associated abdominal injury
Hepatic associated injuries Splenic associated injuries Gastrointestinal associated injuries
Primary US
Primary CT
Positive
Negative
Suspect
Positive
4 (all 4 US + (a)CDS) 2 (all 2 US + (a)CDS) 0
3 (2 FAST, 1 US + (a)CDS) 0 .. 2
3 (1 FAST, 2 US + (a)CDS) 2 (1 FAST, 1 US + (a)CDS) 0
1 (conducted due to multiple trauma) 1 (conducted due to multiple trauma) 0
Total number
11 5 2
Primary US correctly diagnosed 4/11 hepatic injuries and suspected a liver injury in 3 cases. Three hepatic injuries were missed in the initial US exam which was also false negative for renal injuries in these patients and diagnosed by CT (n = 2) or follow-up US + (a)CDS (n = 1). One liver grade III injury and one splenic rupture grade I were correctly diagnosed by CT, conducted primarily due to multiple trauma. Besides this splenic grade I injury, all other four splenic injuries were either correctly diagnosed (n = 2; once a grade II injury was confirmed by CT which was conducted due to unknown reasons 14 years ago and which would be nowadays only followed by US + (a)CDS or investigated by MRI at our institution) or suspected (n = 2) by the initial US exam and diagnosed by an additionally performed CT (conducted due to multiple trauma in the first and due to the suspect US findings in the other 3 patients). A CT was in total conducted in 8/11 patients with hepatic injuries (in 7 cases performed within the acute trauma setting because of multiple trauma and in 1 case performed delayed after a follow-up US exam displayed a fluid collection in the Douglas and Morrison space the following day after the initial FAST was negative for abdominal organ injuries) and 4/5 patients with splenic injuries, as described above. Associated gastrointestinal injuries were observed in two patients. One patient presented with a wide perineal laceration with a dorsal rectal skeletisation and suspect urethral injury. In this patient the primary US exam + (a)CDS displayed an unilateral grade I renal injury without signs of other intra-abdominal organ impairment. The patient underwent surgery to explore and treat the perineal wound and the suspect urethral injury (which could be excluded by intraoperative antegrade urethrography). The rectal injury was treated by a colostomy of the Colon descendens and Hartmann closure of the distal colon. A radiologically diagnosed instable pelvis fracture was stabilized during the same surgery. The second patient with an associated gastrointestinal injury presented with a wound of the abdominal wall. The FAST study showed a renal laceration on the right side and suspected an injury of the liver. An additively performed CT confirmed the grade IV renal injury and diagnosed a rupture of the Linea alba with herniation of small bowel and a grade II liver injury, next to a stable pedicle fracture of L5. The consecutive explorative surgery excluded a penetrating bowel or other abdominal organ injuries. Besides closure of the abdominal wall laceration, a jejunostomy was performed due to severe traumatic brain injury grade III (diagnosed in the additionally performed cerebral CT scan) for further enteral nourishment of the patient. The grade IV renal injury of this patient was treated conservatively.
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false negative for renal injuries in these patients and diagnosed by CT (n = 2) or follow-up US + (a)CDS (n = 1) (see Table 3, case #1, #3, and #5, respectively). Splenic injuries (n = 5) were primarily assessed by US in four patients and were correctly diagnosed in two and suspected in the other two patients by the initial US exam (Table 5). Noteworthy, all parenchymal liver and spleen injuries, which were of grades I–III in the majority of our patients, were managed conservatively. Only one patient with multiple trauma, suffering from a liver laceration grade IV associated with a splenic rupture grade III, and a grade III renal injury, required peritoneal drainage performed eight days after trauma due to breathing difficulties because of the intraabdominal blood accumulation. Of note, three CT exams conducted due to multiple trauma in the acute trauma setting unexpectedly diagnosed vertebral fractures next to other associated abdominal organ injuries. These vertebral fractures however were of stable character and did not require surgical intervention. All patients were followed by US; this included two to fourteen examinations per patient with a median of three US studies per patient. Ten patients underwent a delayed abdominal CT, which was mainly performed because of associated injuries (n = 9); in one case delayed CT was performed because of persisting macrohaematuria. Only one patient with a grade IV renal injury was re-staged by a repeated CT due to haemodynamic instability and eventually underwent a partial nephrectomy. Another patient underwent an abdominal plain film (kidney, ureter, bladder film — KUB) after undergoing a contrast-enhanced CT for assessment of urinary leakage, which revealed a grade III renal injury; this patient was managed conservatively. Delayed renal scintigraphy was conducted in six patients in order to assess renal function, and repeated in 2 patients during further follow-up. Indications for DMSA were severe injury, cotemporaneous UTI, and previous surgery (one patient was evaluated by DMSA after grade III renal injury at the site of a previously performed Anderson–Hynes pyeloplasty for obstruction of the uretero-pelvic junction). The median hospital stay was six days (range = 1–73 days). A longer hospital stay, however, was mainly required in multiple trauma patients because of associated injuries (range = 5–73 days, median = 17 days). All our patients were followed by US in order to document renal healing. Noteworthy, no late or routine follow-up CT was conducted for assessment of renal healing. The general outcome regarding renal injuries was favourable in the majority of our patients, with a renal preservation rate of 95.7%. 3. Discussion In general, renal injuries are rare injuries in childhood and account for about 2% of all traumatic injuries. Blunt abdominal trauma is the main cause for renal injuries in children and may affect the kidney in 10% to 20% [13–16]. Renal injuries are mainly associated with high velocity trauma due to vehicle or sports accidents [17]. The minority of paediatric renal injuries (which account for up to 10%) are attributed to penetrating abdominal trauma such as gunshot or stab injuries [17,18]. Children are more susceptible to renal injuries than adults because of the specific paediatric anatomic constitution which includes lack of perirenal fat, relative large size of the kidney compared to the rest of the body, and less ossified and more pliable thoracic cage [18,19]. In our cases, most renal injuries were of minor severity and mainly occurred in children older than 10 years and adolescents. However, the grade of injury increased with age and was associated with multiple trauma and additional injuries, mandating nephrectomy in both grade V renal injuries. Based on advances in diagnosis and management, a non-operative management was generally favoured in all patients, which was successful in 91.5% of our patients. Renal
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preservation was possible in 95.7%, which is comparable to renal salvage rates of other studies [17,20,21]. Since CT is – particularly in paediatric patients – associated with potential harmful side effects of ionizing radiation and thereby increased risk of (potentially fatal) cancer induction, the routine application of CT examinations for mild to moderate trauma is being reconsidered [12,22,23]. It has been recently speculated that about 10% to 30% of all CTs may be unnecessary as they are irrationally applied without profound justification, not adding any diagnostically relevant information or altering clinical management [24]. In paediatric renal trauma CT has been propagated as the first line diagnostic assessment tool for accurate staging and grading which directs an informed management decision [2,17,20,21,25]. CT has been internationally implemented as the standard of care because of its accuracy, its wide spread availability, its reliability and its ability to diagnose abdominal, retroperitoneal, skeletal, and pelvic urologic as well as non-urologic injuries [16,26]. In our patient cohort, however, US correctly depicted the renal injuries in ~87% of all initial examinations, which is comparable with the correct diagnostic percentage of primary CT examinations (93%). The time delay for those initial sonographically missed diagnoses did not alter the management or outcome nor caused any complications. Thereby – as part of a learning curve over time, also influenced by increasing radiation awareness – primary CT was only conducted in half of the patients (55%) and was limited to patients with multiple trauma or additional injuries, or inconclusive US findings. One initial CT performed in a patient with multiple trauma was even false negative for a renal grade I injury (renal contusion) which was eventually diagnosed sonographically during follow-up by (a)CDS. Nevertheless, the CT results of our patients, diagnosing not only renal but also associated abdominal organ or spinal column injuries, certainly helped the treating physicians in defining the management of these patients, partly by assuring the abdominal US findings. However, at our institution the CT examination would be nowadays, except in patients with multiple trauma or in case of immediate need for action due to acute deterioration of the clinical status, replaced by MRI, in case, that there is a need for additional imaging next to the US exam which should include (a)CDS. Concerning the diagnosis of underlying unknown congenital kidney malformations or even tumours, possibly prone to higher degree injuries in renal trauma, the initial US + (a)CDS examination documented unknown congenital kidney abnormalities of minor pathology in three patients of our patient cohort. These congenital pathologies were all diagnosed in patients with a renal contusion and were sonographically followed but did not require further diagnostic imaging. Based on these findings, we believe that possibly existing congenital abnormalities are not justifying the routine use of CT in renal traumas in all children and that US can reliably depict these disorders which may then still be examined by further diagnostic imaging if needed. Recently, repeated CT imaging has been recommended to re-assess all paediatric grades II to V renal injuries at 48 h if haemodynamically stable or earlier if required clinically, and in all grades IV to V renal injuries at 1 to 3 months to document adequate healing and function, possibly replaced by renography at that time [17,25]. At our institution, only one repeated CT was performed in one patient because of haemodynamic instability and due to a grade IV renal injury which eventually necessitated partial nephrectomy. All our patients were re-assessed by repeated US, significantly reducing radiation burden and without negative impact on management and outcome. A recent study generally stated renal US as the primary surveillance imaging method for patients with renal injury [27]. In contrast to our opinion, the same study, however, documented that an early US re-evaluation might be unnecessary as they saw US findings inconclusive without a repeat CT in two of their patients who required urinary drainage procedures [27]. Although US has been emphasised as a convenient, easily accessible, non-invasive, and inexpensive
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imaging method without ionizing radiation, its reliability depends on the examiner's skills, training, and anatomic and pathologic knowledge as well as the available US device/transducers. This may vary, and a skilled dedicated paediatric radiologist is not always available; furthermore US cannot reliably distinguish between extra-vasated urine, blood and other fluid. Thus the value of US has been discussed controversially for assessment of blunt abdominal trauma [2,3,28]. In children, however, the use of US with (a)CDS has been proposed as the first line imaging technique particularly with a mild or moderate trauma history, frequently establishing the initial diagnosis and potentially prompting CT as a complementary imaging method when needed [3,9,12,22]. In our patients, the detailed and dedicated US study, often including an (a)CDS assessment, being performed by well-trained paediatric surgeons and/or paediatric radiologists, has been sufficient and reliable for initial diagnosis and further management (also to decide on whether complementary imaging is necessary), and it enabled a favourable renal preservation rate of 95.7%. This approach resulted in a minor diagnostic delay in only six patients, but even there it did not alter the management or result in complications or an adverse outcome. In the future, contrastenhanced US may even further improve US potential allowing for a more robust sonographic renal injury assessment and thus enable a further reduction of radiating imaging [29–32]. Although we, based on our results, advocate to use US as a first line diagnostic imaging method in paediatric patients with renal trauma whenever possible, CT should always have its diagnostic value in hospitals where US is not frequently used or not available in order to enable conservative management of traumatized kidneys with higher degree lacerations.
Older imaging techniques such as IVU have been replaced by CT and sometimes MRI. Still, in some rare situations a focussed adapted IVU or just an abdominal plain film documenting the kidney, ureter and bladder (KUB) after contrast-enhanced CT for assessment of urinary leakage may be a valuable option; the latter approach helped to assess a grade III renal injury in one patient of our cohort. A focussed IVU was performed in one of our patients after initial US had depicted an absent renal perfusion, to confirm absent renal enhancement and secretion (Fig. 5a and b); nowadays this IVU would be replaced by immediate contrast-enhanced CT but – 10 years ago with only a dislocated CT scanner at that time at our institution – it seemed to be the most feasible available imaging technique. MRI is a little cumbersome in the acute setting for initial evaluation due to availability and handling, particularly with need for sedation or anaesthesia, as well as its longer duration. Contrast-enhanced MRI with MR-urography (MRU) however can be very helpful in assessing renal injuries as an add-on study or for followup, possibly replacing follow-up CTs. In one of our patients a traumatic urinoma was suspected by follow-up US after a grade IV renal injury; before deciding on treatment the suspicion was confirmed and topographically assessed by diuretic MR-urography with late acquisitions (Fig. 6a–d). The urinoma was, eventually, managed by percutaneous nephrostomy. Renal Tc99m DMSA scintigraphy is today reserved for follow-up examinations to evaluate renal function and scarring after severe injury as performed in six selected cases; in the future this also might be replaced by (functional) MR-urography [33]. All our patients were followed by US in order to document renal healing; no late routine follow-up CT for assessment of renal healing was conducted; in six selected cases, US was complemented by Tc99m DMSA scintigraphy.
Fig. 7. Imaging algorithm for paediatric patients with suspect renal trauma. The algorithm highlights US + (a)CDS as a key imaging modality in patients with mild to moderate renal trauma and as the main follow-up tool to monitor patients with a traumatic renal injury. A mild renal trauma is defined by a low energy injury to the kidney bed caused by coplanar falls on objects or hits by low-weight objects without visible signs of trauma, while a moderate renal trauma is clinically considered with the occurrence of visible trauma signs such as cuts, contusion marks or bruises — in context with moderate external forces impacting on the kidney area in the patient history. A severe renal trauma is defined by a rapid deceleration injury, fall from height, or direct flank injury caused by high external forces, also including penetrating injuries. FAST is recommended as the first investigation performed during clinical assessment of patients with severe or multiple trauma at the ER to provide quick information about the abdominal situation within the acute trauma setting. CT remains the next imaging step in all patients with multiple trauma unless unstable. Of note, US should be complemented by (a)CDS in all patients with mild to moderate renal trauma within the primary assessment and may be also performed in stable patients with severe renal trauma, if the direct impact was only to the kidney and if high quality US is quickly available. This algorithm has been modified based on the recommendation proposed by the ESPR Task uroradiology task force and ESUR paediatric working group (Riccabona et al. 2010 and 2011 [9,12]).
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Based on the findings of this retrospective study, we conclude that US (including (a)CDS) can be safely and reliably applied as a first line diagnostic imaging technique in renal injuries after mild to moderate paediatric blunt abdominal trauma. A contrast-enhanced CT should be reserved for patients with multiple or severe trauma, those with suspicion of associated injuries, or those with clinical or sonographic uncertainty — which potentially will be in part replaceable by MRI, particularly in stable patients. To illustrate the conclusions of our study, we established a diagnostic algorithm for patients with suspect renal trauma (Fig. 7). In our opinion, free fluid of unknown origin in the detailed US study is per se not indicating a CT examination in stable patients. With regards to our results and considering the ALARA principle, the above mentioned imaging algorithm appears safely applicable for assessment of paediatric renal injuries in the initial trauma setting and for follow-up, and advocates reduction of unnecessary radiation exposure to the paediatric patient. To achieve this, high level dedicated paediatric US must be made available for children 24 h a day throughout the year. References [1] Stanescu AL, Gross JA, Bittle M, et al. Imaging of blunt abdominal trauma. Semin Roentgenol 2006;41:196–208. [2] Eeg KR, Khoury AE, Halachmi S, et al. Single center experience with application of the ALARA concept to serial imaging studies after blunt renal trauma in children — is ultrasound enough? J Urol 2009;181:1834–40. [3] Lougué-Sorgho LC, Lambot K, Gorincour G. Kidney trauma in children: state of the art medical imaging. J Radiol 2006;87:275–83. [4] Shah NB, Platt SL. ALARA: is there a cause for alarm? Reducing radiation risks from computed tomography scanning in children. Curr Opin Pediatr 2008;20:243–7. [5] Brenner D, Elliston C, Hall E, et al. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001;176:289–96. [6] Brenner DJ, Hall EJ. Computed tomography — an increasing source of radiation exposure. N Engl J Med 2007;357:2277–84. [7] Brody AS, Frush DP, Huda W, et al. Radiation risk to children from computed tomography. Pediatrics 2007;120:677–82. [8] Pietrera P, Badachi Y, Liard A, et al. Ultrasound for initial evaluation of posttraumatic renal lesions in children. J Radiol 2001;82:833–8 [French]. [9] Riccabona M, Avni FE, Dacher JN, et al. ESPR uroradiology task force and ESUR paediatric working group: imaging and procedural recommendations in paediatric uroradiology, part III. Minutes of the ESPR uroradiology task force mini-symposium on intravenous urography, uro-CT and MR-urography in childhood. Pediatr Radiol 2010;40:1315–20. [10] Moore EE, Shackford SR, Pachter HL, et al. Organ injury scaling: spleen, liver, and kidney. J Trauma 1989;29:1664–6. [11] Damasio MB, Darge K, Riccabona M. Multidetector-CT in the paediatric urinary tract. Eur J Radiol 2013;82(7):1118–25.
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