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Management of Pediatric Blunt Abdominal Trauma at a Major Trauma Centre: Is Ultrasound a Reliable Indicator of Injury?

Muhammad Riyad Peeraully, Paul Berkeley Jackson, Ramnik Patel, Shailinder Jit Singh
Department of Pediatric Surgery, Queen’s Medical Centre, Nottingham University Hospitals, Nottingham, UK

 

Abstract

Introduction: Abdominal computed tomography (CT) is the gold standard for investigation of blunt abdominal trauma but involves significant radiation exposure which is of especial concern in the pediatric population. Conservative management of stable solid viscus injuries (SVI) in children is successful but risks delayed management of associated hollow viscus injuries (HVI). This retrospective cohort study analyses the management of paediatric blunt abdominal trauma at a major trauma centre.

Methods: For the period 2007-2012, we identified patients less than 16 years admitted to our hospital with blunt abdominal trauma that underwent emergency abdominal imaging. Demographic and clinical data were obtained from contemporaneous records.

Results: Forty-four children were identified for inclusion. Thirteen (30%) underwent formal abdominal ultrasound (US) prior to CT. There were no false negatives (sensitivity 100%) or false positives (specificity 100%) on US in comparison to CT. Nine (20%) were investigated with US alone and managed non-operatively. There was normal imaging in 19 (43%), SVI in 20 (45%) and free intraperitoneal fluid (FIPF) without SVI in 5 (11%). Management was conservative in 40 (91%), including 2 (5%) who had FIPF without SVI. Four (9%) underwent laparotomy, two having free intraperitoneal air and two having FIPF without SVI.

Conclusion: This study identified no difference in sensitivity or specificity between US (performed by a paediatric radiologist) and CT in detecting intra-abdominal injury. In stable children with evidence of FIPF but no definite SVI or HVI, a conservative approach may be appropriate with consideration for serial imaging and a low threshold for surgical intervention.

Keywords: child, abdominal injuries, laparotomy, ultrasonography, tomography, radiograph, computed axial tomogram (CAT)

 

Correspondence

Riyad Peeraully and Shailinder Singh
Department of Pediatric Surgery
Queen’s Medical Centre, Nottingham University Hospitals NHS Trust
Derby Road, Nottingham, NG7 2UH
Email: This email address is being protected from spambots. You need JavaScript enabled to view it. , This email address is being protected from spambots. You need JavaScript enabled to view it.
Tel.: 0161 276 1234; Fax: 00441162893395

 

Introduction

Abdominal computed tomography (CT) is the gold standard for investigation of blunt abdominal trauma, but involves a significant exposure to ionizing radiation which is of especial concern in the pediatric population. This has been a subject of great interest of late, with a recent cohort study reporting that exposure to CT in childhood increased the incidence of cancer significantly [1,2] reinforcing existing data.

Ultrasound involves no exposure to radiation but is perceived to be a less sensitive imaging modality than CT. The accuracy of US is highly user-dependent and particularly when investigating blunt abdominal trauma in the paediatric setting it relies on the availability of an appropriately trained radiologist to perform the scan and interpret the findings. Deciding on the appropriate imaging methods in the emergency setting is therefore dependent on the availability of resources and consideration of the risk of missing significant injury versus unnecessary exposure to CT radiation.

The move to the non-operative management of a stable solid viscus injury (SVI) in children is a very successful approach [3]. However, the detection and management of hollow viscus injuries (HVI) is a more complex issue and a conservative strategy runs the risk of failing to appropriately and expeditiously treat HVI [4, 5]. The presence of free intraperitoneal or retroperitoneal fluid (FIPF) on CT and US is usually attributed to SVI, while free intraperitoneal or retroperitoneal air (FIPA) is diagnostic of full thickness HVI. Studies suggest that US can be useful in detecting FIPA in blunt abdominal injury, although CT is regarded as being able to more accurately detect small amounts of FIPA [6, 7]. However, lack of FIPA does not exclude the presence of HVI; when no evidence of SVI is detected the presence of FIPF may be attributable to non-perforating HVI including focal bowel haematomas, partial tears and mesenteric injuries.

One approach to this issue is to suggest that FIPF without evidence of SVI necessitates laparotomy. While this strategy would clearly minimise the risk of missing significant trauma undetected on imaging, it carries the obvious disadvantages associated with a major operation including potential complications and prolonged hospital stay. The alternative is to adopt a non-operative approach in cases where a small amount of FIPF is present in a hemodynamically stable child and use clinical judgement based on serial physical examination to determine if intervention is indicated.

This study looks at cases of paediatric blunt abdominal trauma admitted over a five year period to a major trauma centre in the UK and analyses the subsequent management of these children to assess the experience of the institution in investigating and treating them.

Methods

For the five year period 2007-2012, we reviewed the records of the radiology department at Queen’s Medical Centre (QMC, Nottingham, UK), a designated major trauma centre, to identify all patients under 16 years who had sustained blunt abdominal trauma and subsequently undergone imaging of the abdomen and pelvis. FAST scans (focused assessment with sonography for trauma) were performed by emergency department staff but formal abdominal US scans were performed by paediatric radiologists. Patients who were transferred to QMC for specialist management after having had imaging performed at a peripheral hospital were excluded, as were children with penetrating abdominal trauma.

Demographic data and information regarding the mechanism of trauma, clinical findings, imaging reports, management and outcomes were obtained from radiology department records. Contemporaneous emergency department notes and inpatient notes were also used. Patients were included irrespective of concomitant injuries to other body parts. Data were compiled and analysed using Microsoft Excel.

Results

Forty-four children were identified for inclusion. Boys accounted for 33 (75%) and the median age was 13 years 4 months (range 2 months to 15 years 9 months). The mechanisms of injury are detailed in Table 1. A significant associated non-abdominal injury was sustained by 15 (34%), of whom the majority were involved in a road traffic accident (RTA). These injuries included traumatic brain injury, long bone and spinal fractures, pneumothorax and pulmonary contusions.

Table 1. Mechanisms of injury and imaging outcomes in children sustaining blunt abdominal trauma. RTA - road traffic accident; NAI - non-accidental injury.

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The severities of the injuries sustained are indicated in Tables 2 and 3. There were 21 (48%) with injuries to a single anatomical region, 9 (20%) to two regions, 1 (2%) to three regions and 1 (2%) to four regions. Abdominal organ injuries were confined to a single organ in 15 (34%) and were to multiple organs in 8 (18%). The median Injury Severity Score was 4 (range 0-25) with 7 cases of polytrauma (ISS>15). Nine children (20%) with a range of mechanisms of injury were investigated by formal abdominal US only (Table 1). Although 8 had normal scans, one had findings of a small splenic laceration with perisplenic and pelvic FIPF following a handlebar injury. He was managed conservatively without any further imaging and discharged after 3 days.

Table 2. Abbreviated injury Scale grades by anatomical region for each injury

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Table 3. Organ Injury Scale grades for abdominal visceral injuries

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Thirteen (30%) underwent formal US prior to CT (Table 1). There were no false negatives (sensitivity 100%) or false positives (specificity 100%) on US in comparison with CT (Table 4). In 5 (11%) a FAST scan was performed prior to CT. FIPF was correctly identified in 3 children, but FAST scans reported as normal in the other 2 failed to detect FIPF subsequently identified on CT (a large volume in one child (also detected on formal US prior to CT) and small volume in the other).

Table 4. Contingency table for imaging findings.

table 4

In 19 (43%), there was no significant intraabdominal finding on imaging (Fig 1). These children were managed conservatively and none required any subsequent imaging. Twenty (45%) had evidence of SVI. Management was conservative in 19 (43%) of whom 15 (34%) had FIPF and 4 (9%) did not. The remaining child had an initial FAST scan which showed only FIPF, but subsequent CT showed FIPA in addition to FIPF and she proceeded to laparotomy on day 1 where a perforated pylorus and duodenum (D1-D2) were repaired. Interval CT on day 10 showed a pancreatic tear so a distal pancreatectomy was performed on day 13. This child had a prolonged stay of 35 days in hospital and had a follow-up US one month after discharge.

Figure 1: Management of children with blunt abdominal trauma. Imaging findings of solid viscus injury (SVI), free intraperitoneal fluid (FIPF) and free intraperitoneal air (FIPA) are shown along with subsequent management (CON, conservative; LAP, laparotomy).

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Five (11%) had no obvious SVI despite the presence of FIPF. Two were managed conservatively and following initial CT on day 1 had repeat CT on day 2. The presence of associated injuries (pelvic fractures in one case and multiple long bone fractures and significant head injury in the other) resulted in prolonged hospital stays of 15 and 23 days in these cases. The remaining three in this group underwent laparotomy. One had FIPA and FIPF and was taken to theatre on day 1 where a jejunal perforation was oversewn - CT was the only imaging modality used in this case. The other two underwent laparotomy despite the absence of FIPA. The first was taken to theatre on day 1 due to increasing pain and tachycardia despite only a small volume of FIPF on CT and required closure of a mesenteric tear at the ileocecal junction. The second underwent laparotomy on day 1 in view of a moderate volume of FIPF on CT (with no obvious SVI) and required closure of a mesenteric tear 10 cm proximal to the ileocecal junction.

The median length of stay in hospital was 4 days (range 1-35 days) and the median length of follow-up was 23 months (range 6-63 months). At the time the data for this study was collected, none of the children in this cohort had been readmitted to hospital following their initial stay as a result of morbidity related to any abdominal injuries.

Discussion

The incidence of paediatric blunt abdominal trauma in the UK is low but is a cause of significant morbidity and mortality [8–10]. The abdominal viscera are relatively unprotected in children and are much more at risk of significant injury than in adults. Children are prone to sustaining blunt abdominal injuries via a range of mechanisms, the majority being unintentional [8, 9]. In keeping with the published literature, most of the injuries in this study were associated with bicycle riding and involvement in a road traffic accident (RTA) as a passenger or pedestrian [8, 9]. A limitation of this study is that only children whose initial presentation was of sufficient concern to warrant emergency imaging of their abdomen and pelvis were included, therefore preventing any comment on the proportion of children sustaining blunt abdominal injury undergoing imaging.

Most solid viscus injuries in children can be successfully managed without surgical intervention, with accurate and timely imaging and serial clinical review guiding management decisions including level of care, degree of monitoring, duration of bed rest and avoidance of active pursuits [9, 10]. Hollow viscus injuries in children pose a challenge in both diagnostic and therapeutic terms. While bowel wall haematomas and serosal tears may be managed conservatively in a similar manner to an SVI, expeditious exploration and repair of bowel perforations and significant mesenteric tears are critical to reducing morbidity and mortality [11–13].

In this study, there were two cases in which FAST scans missed significant injuries, consistent with previous data on the modest sensitivity of this modality in such scenarios [14– 16]. Importantly, we were unable to detect a difference between formal US (performed by a radiologist with paediatric training) and CT in their sensitivity or specificity in detecting evidence of significant intra-abdominal injury. This is in keeping with published reports regarding the accuracy of US in cases of paediatric blunt abdominal trauma [10, 17–20]. Nine children in this study were successfully managed after imaging with US alone and four in whom there were no abnormalities on CT following normal US were also treated conservatively. As in previous reports [10, 17] this would suggest that US performed by a paediatric radiologist is an appropriate initial investigation in some cases when evaluating paediatric blunt abdominal trauma. The provision of paediatric radiology cover, especially out of normal working hours, may reduce unnecessary irradiation of children following such injuries.

The trauma guidelines for adults are not appropriate for entire paediatric age group and the imaging needs of each child should be evaluated individually. There is no time constraint for this assessment and as such, the timing and necessity of imaging should be based on the clinical picture. While there may be no need to image the abdomen if the child has suffered an isolated injury elsewhere, a significant mechanism of injury together with suspicious clinical findings should prompt further investigation.

Evaluation of imaging methods in this paediatric population should balance the risk of missing significant injury against efficient use of resources and unnecessary exposure to radiation, as has been suggested in other studies [10, 19, 21–23]. An abdominal CT exposes a child to around 30 mSv of radiation (the equivalent of 12 years of background radiation) [10] and large-scale studies have provided solid evidence of the risks of malignancy from exposure to CT in childhood [1, 2]. Although US avoids ionising radiation and can be performed at the bedside, it is less sensitive than CT which enables more accurate grading of organ injuries [20]. This may facilitate immediate management more appropriately, but the findings of this study correlate well with previous reports in which the majority of children who have sustained SVI of varying degrees of severity are managed conservatively [10]. In a stable child with FIPF on US and an obvious source in the form of one or more SVIs, there may be little additional clinical benefit in performing CT. Those in whom surgical intervention proves necessary would tend to be clinically unstable and would therefore be more likely to benefit from a CT to identify their injuries, especially HVI. Whilst FIPA is more easily detectable on CT however, it can be reliably detected on US with appropriate training [6, 7, 24]. The use of CT in evaluating paediatric blunt abdominal trauma should be based on senior clinical evaluation where there is a high degree of suspicion, rather than as a routine investigation.

There were four children in this series with FIPF of uncertain origin (no definite SVI or HVI). Two underwent laparotomy, the indications being clinical instability in one and the presence of a moderate amount of FIPF with no obvious source in the other. It should be noted that neither had organ injury scale grades greater than 1 and the ISS was 8 in both cases. The other two had a good outcome following non-operative approaches to management based on only small amounts of FIPF being present in hemodynamically stable children, frequent clinical assessment and repeat imaging at an appropriate interval.

Conclusion

In a child who has sustained blunt abdominal trauma, CT is the gold standard modality of imaging. However, US performed by a radiologist with paediatric training can provide the information needed for appropriate management without the need for CT unless the clinical picture demands it. As the longterm squeal of exposure to ionising radiation in childhood become more apparent, this study encourages the inclusion of US in paediatric trauma imaging algorithms and the more targeted use of CT.

The more challenging patients are the ones with FIPF but no SVI or FIPA. If these findings are from an initial US, it is advisable that CT should follow in these cases. However, the successful conservative management of stable children with FIPF in the absence of clearly detected SVI or HVI is in keeping with current thinking [25–31] which advocates a non-operative approach when the source of FIPF cannot be clearly ascertained from imaging. This approach must be allied to close surveillance, an emphasis on serial physical examination, consideration for serial imaging and a low threshold for surgical intervention in the event of clinical deterioration.

Acknowledgements

The authors would like to thank Dr K Halliday, Dr J Somers, Dr N Broderick and Dr S Mohan (Consultant Paediatric Radiologists) and Mr R Stewart, Mr B Davies, Mr S Motiwale, Mr B More, Mr M Shenoy, Mr A Williams and Mr D Colliver (Consultant Paediatric Surgeons) for their assistance in this study.




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