Blunt abdominal trauma in children

REVIEW C URRENT OPINION Blunt abdominal trauma in children Deborah Schonfeld and Lois K. Lee Purpose of review This review will examine the current evidence regarding pediatric blunt abdominal trauma and the physical exam findings, laboratory values, and radiographic imaging associated with the diagnosis of intraabdominal injuries (IAI), as well as review the current literature on pediatric hollow viscus injuries and emergency department disposition after diagnosis. Recent findings The importance of the seat belt sign on physical examination and screening laboratory data remains controversial, although screening hepatic enzymes are recommended in the evaluation of nonaccidental trauma to identify occult abdominal organ injuries. Focused Assessment with Sonography for Trauma (FAST) has modest sensitivity for hemoperitoneum and IAI in the pediatric trauma patient. Patients with concern for undiagnosed IAI, including bowel injury, may be considered for hospital admission and serial abdominal exams without an increased risk of complications, if an exploratory laparotomy is not performed emergently. Summary Although the FAST exam is not recommended as the sole screening tool to rule out IAI in hemodynamically stable trauma patients, it may be used in conjunction with the physical exam and laboratory findings to identify children at risk for IAI. Children with a normal physical exam and normal abdominal CT may not require routine hospitalization after blunt abdominal trauma. Keywords abdominal trauma, intra-abdominal injury, pediatrics INTRODUCTION Injuries continue to be a leading cause of death and disability in children and adolescents less than 18 years old [1]. Abdominal trauma sustained from motor vehicle crashes (MVC), falls, sports-related injuries, or other causes can result in substantial mortality from solid organ or hollow viscus injury [2,3]. Despite the frequency with which abdominal trauma occurs in children, there is still controversy over the optimal evaluation strategy to identify intra-abdominal injury (IAI). The purpose of this review is to highlight the recent studies on the utility of physical exam findings, laboratory testing, and radiographic imaging in the assessment of the pediatric abdominal trauma patient, and to examine the recent literature regarding traumatic bowel injuries and disposition after emergency department (ED) evaluation for abdominal trauma. PHYSICAL EXAM FINDINGS IN THE EVALUATION OF ABDOMINAL TRAUMA Although physical exam findings of abdominal tenderness are an integral part of the decision making in the evaluation of pediatric abdominal trauma, the importance of abdominal wall bruising associated with a seat belt in the setting of a MVC varies among studies. The seat belt sign consists of a well-defined area of ecchymosis, erythema or abrasions that occurs on the abdomen of a restrained occupant involved in a MVC. It may be seen in children wearing an improperly fitted seat belt that crosses the abdomen instead of the pelvis. In addition to abdominal wall bruising, the seat belt syndrome also includes vertebral Chance fractures resulting from the flexion distraction injury of the spine at the fixed fulcrum site of the lap belt, and abdominal injuries from compression of intra-abdominal organs between the seat belt and the bony vertebral column [4]. A porcine animal model of seat belt related injuries demonstrated that direct Division of Emergency Medicine, Children s Hospital, Boston, Harvard Medical School, Boston, Massachusetts, USA Correspondence to Lois K. Lee, MD, MPH, Division of Emergency Medicine, Children s Hospital, Boston, 300 Longwood Ave, Boston, MA 02115, USA. Tel: +1 617 355 5089; fax: +1 617 730 0335; e-mail: lois.lee@childrens.harvard.edu Curr Opin Pediatr 2012, 24:314 318 DOI:10.1097/MOP.0b013e328352de97 www.co-pediatrics.com Volume 24 Number 3 June 2012

Blunt abdominal trauma in children Schonfeld and Lee KEY POINTS Screening laboratory values have not been well established for the evaluation of pediatric intraabdominal injuries (IAI) after trauma; however, in the evaluation of child abuse, screening with transaminases is recommended to identify children at risk for occult abdominal injury for definitive testing. The Focused Assessment with Sonography for Trauma exam has modest sensitivity for the identification of hemoperitoneum or IAI in children with blunt abdominal trauma, but may be useful in conjunction with physical examination and laboratory results. Children with a normal abdominal computed tomography and normal physical exam findings after blunt abdominal trauma may not require routine hospitalization. compression of the specific organ under the seat belt was the mechanism causing the injuries, because the solid organ injuries were only generated with belt loading in the upper abdomen, whereas hollow viscus organ and bladder injuries were associated with lower abdomen belt loading [5]. A retrospective study of 331 children involved in MVCs, 54 of whom had abdominal wall bruising, determined that this finding had a sensitivity of 25% for identifying IAI and a specificity of 85%. Even after addition of the presence of abdominal tenderness, the relative risk of an abdominal injury identified on computed tomography (CT) scan or during surgery was not significant [relative risk (RR) 1.6, 95% confidence interval (CI) 0.546 4.68] [6]. In another retrospective study of children with abdominal bruising after a MVC, a multivariate logistic regression analysis determined that predictors for intestinal injuries included abdominal bruising when combined with a pulse rate of more than 120 per minute, presence of free intra-abdominal fluid on ultrasound or CT, and an associated lumbar fracture. The authors concluded that an abdominal exploration should be considered for these patients [4]. LABORATORY EVALUATION IN ABDOMINAL TRAUMA Laboratory studies are one potential adjunct in the evaluation of children with abdominal trauma. Various cutoff values for liver transaminases to assess for liver injury have been proposed to aid in the decision making for CT evaluation after abdominal trauma. A retrospective study of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in the setting of blunt abdominal trauma found a correlation between AST/ALT levels and severity of liver injury; however, even among patients with no discernable liver injury on CT, half had elevated AST/ALT levels. Therefore, the authors concluded cutoff values for AST/ALT under which liver injury could be excluded could not be determined, as it is likely that elevated AST/ALT levels may be due to moderate hepatic cytolysis in the setting of trauma, even though a specific injury may not be visualized on CT scan [7]. In contrast, a study comparing 51 children with liver injury with65childrenwithother,nonliver,abdominal injuries used the receiver operating characteristic curve to determine that an ALT value of 104 IU/l could identify the presence of liver injury with an area under the curve of 0.945 (95% CI, 0.905 0985). When using this level to identify clinically significant (grades III, IV, V) liver injuries the sensitivity was 100% (95% CI 89 100%), specificity 70% (95% CI 59 79%), positive predictive value (PPV) 57%, and negative predictive value (NPV) 100% [8]. Given the varying methodologies and outcome definitions for these studies analyzing the use of laboratory values to screen for abdominal solid organ injuries, the use of laboratory tests may be most valuable when combined with other physical exam and diagnostic test results, rather than in isolation. An exception to this may be the use of screening transaminases in the evaluation of suspected nonaccidental trauma [9]. In a prospective study using hepatic enzymes in the assessment of children with potential physical abuse, an AST or ALT more than 80 IU/l had a sensitivity of 77% (95% CI 65 87%) and a specificity of 82% (95% CI 80 84%) for abdominal injury even in children with no abdominal bruising, tenderness, or distention. As a result the authors recommended abdominal imaging at a threshold level of 80 IU/l, as, in the evaluation of a potentially abused child, the identification of occult abdominal injuries may provide important forensic information [10]. ABDOMINAL ULTRASOUND/FOCUSED ASSESSMENT WITH SONOGRAPHY FOR TRAUMA EVALUATION Another tool in the evaluation of the pediatric trauma patient is the Focused Assessment With Sonography for Trauma (FAST), a rapid and noninvasive bedside ultrasound examination used for the evaluation of blunt abdominal trauma. The focus of this sonographic technique is to evaluate the right upper quadrant, left upper quadrant, pelvis and pericardial windows for free peritoneal fluid, as 1040-8703 ß 2012 Wolters Kluwer Health Lippincott Williams & Wilkins www.co-pediatrics.com 315

Emergency and critical care medicine evidence of hemorrhage or other abnormal fluids (e.g., bile, urine) [11]. The American College of Surgeons in the Advanced Trauma Life Support (ATLS), eighth edition, recognizes FAST as an adjunct diagnostic option for the evaluation of abdominal trauma in pediatric patients [12], but the optimal use of FAST in pediatric trauma remains controversial, with great variability in its use [13 15]. FAST aims to detect free intraperitoneal fluid (presumed to be blood in the setting of trauma), but more than one-third of low-grade pediatric liver or spleen injuries are not associated with free fluid [2]. A meta-analysis to determine the test performance of FAST had a sensitivity of 66% (95% CI 56 75%) for identifying children with hemoperitoneum, but the sensitivity decreased to 50% (95% CI 41 59%) for identifying IAI, regardless of the presence of hemoperitoneum [16]. A prospective observational study of 357 pediatric patients with blunt abdominal trauma determined that for clinically important free fluid, defined as moderate or greater amount of intraperitoneal free fluid on CT or injury requiring surgery, FAST had a sensitivity of 52% (95% CI 31 73%), specificity 96% (95% CI 93 98%), PPV 48% (95% CI 28 69%), and NPV of 97% (95% CI 94 98%) [17 && ]. In an effort to increase its utility as a screening tool to detect solid organ injuries, the use of FAST combined with other factors has been studied. The combination of FAST with elevated liver transaminases (ALT or AST > 100 IU/l) was found in one study to improve sensitivity (88%) and NPV (96%) for free intraperitoneal fluid or IAI in pediatric patients with blunt abdominal trauma [18]. The Blunt Abdominal Trauma in Children (BATiC) score combined the results of abdominal Doppler ultrasound with three physical exam findings and six laboratory values to identify children with IAI without CT imaging. Each element in the score was assigned a value, and a score of 7 or less had a sensitivity of 91%, specificity 84%, PPV 64%, and NPV 97% for the detection of intra-abdominal organ injury [19]. To improve the ability of ultrasound to identify solid organ injuries in children, contrast enhanced ultrasound (CEUS), which uses intravenous contrast, has been shown to accurately visualize intra-abdominal parenchymal injury [20]. There is preliminary evidence which suggests that CEUS may be more accurate than regular ultrasound in the detection of solid organ injuries in children [21]. A positive FAST exam in the pediatric trauma patient suggests hemoperitoneum from abdominal injury, and, therefore, requires further evaluation to delineate the specific nature and extent of IAI. If the FAST exam is negative for free fluid; however, given its modest sensitivity for the detection of intraperitoneal free fluid, it should not be used as the sole diagnostic test to rule out the presence of IAI in the hemodynamically stable patient. The FAST exam may play a specific role in surgical decision making in a subset of patients [22], including the hemodynamically unstable child, in whom sonographic free fluid should prompt rapid blood transfusion and/or emergent laparotomy without further imaging. COMPUTED TOMOGRAPHY EVALUATION Abdominal CT remains the diagnostic test of choice for the evaluation of IAI. The CT diagnosis of abdominal injury also guides nonoperative decisions such as duration of hospitalization, intensity of care, length of activity restriction, and follow up [3,23]. CT imaging, however, results in substantial exposure to ionizing radiation, which may significantly increase a child s lifetime risk of lethal malignancy [24,25,26 & ]. Unfortunately, children who are initially evaluated with abdominal CTs at community hospitals frequently undergo repeat CT scans after transfer to pediatric trauma centers, further increasing their exposure to ionizing radiation [27 &,28]. Given these radiation risks, there are ongoing attempts to help clinicians risk stratify patients for IAI with clinical prediction rules [19,29]. In 2009 Holmes et al. [29] prospectively validated their previously derived clinical prediction rule for the identification of children at very low risk for IAI after blunt torso trauma. This rule included six high-risk variables, and the presence of any of the variables indicated that the child was not at low risk: low age-adjusted systolic blood pressure, abdominal tenderness, femur fracture, increased liver enzyme levels (serum AST > 200 IU/l or ALT > 125 IU/l), microscopic hematuria (urinalysis > 5 red blood cells/high power field), or initial hematocrit less than 30%. This rule had a sensitivity of 95% (95% CI 90 98%) and specificity of 37% (95% CI 34 40%). It missed eight IAI, none of whom required acute intervention. The Pediatric Emergency Care Applied Research Network (PECARN) recently conducted a multicenter prospective observational study of pediatric blunt abdominal trauma to derive and validate a clinical decision rule to identify children at low risk for IAI who may not require CT evaluation. The results of this study should result in a more accurate and reliable decision rule and will hopefully limit the use of CT imaging to children with a nonnegligible risk for IAI after trauma. 316 www.co-pediatrics.com Volume 24 Number 3 June 2012

Blunt abdominal trauma in children Schonfeld and Lee BOWEL INJURY AND FREE INTRAPERITONEAL FLUID ON COMPUTED TOMOGRAPHY Although CT is highly sensitive for the detection of solid organ injury, it is not as accurate in the identification of hollow viscus injury. Blunt bowel injury is much less common than solid organ injury after trauma, occurring in fewer than 10% of children with blunt abdominal trauma, and both the clinical and CT diagnosis of a perforated bowel injury can be challenging [2]. CT findings in the setting of bowel injury can include peritoneal fluid without solid organ injury, bowel wall enhancement and thickening, extraluminal gas, bowel wall discontinuity, and mesenteric stranding [2,30]. To determine the clinical significance of isolated free intraperitoneal fluid (free fluid without any solid parenchymal injury or pelvic fracture), Christiano et al. [31] retrospectively analyzed 94 pediatric trauma patients hospitalized with isolated free intraperitoneal fluid on abdominal CT, and only three patients were taken to surgery after developing peritonitis. The only statistically significant predictors for abdominal surgery were the presence of abdominal tenderness on initial physical exam and the quantity of free intraperitoneal fluid on initial CT. The authors concluded that an initial nonoperative approach to children with isolated intraperitoneal fluid on CT with serial abdominal exams is justified. The risk of expectant management, however, is that delayed surgical intervention may lead to adverse consequences. In a multi-institutional retrospective study of 214 patients diagnosed with bowel injury after trauma, there were no statistically significant differences in the early and late complications or total hospital length of stay based on the time interval from injury to intervention (<6, 6 12, 12 24, and >24 h). The authors concluded that, although operative management should be expeditiously pursued once a diagnosis of bowel injury is established, in those children with unclear findings, especially with other injuries (e.g., traumatic brain injuries), observation and serial examinations may be an appropriate alternative to emergency exploratory laparotomy or repeated CT scans [32]. DISPOSITION For hemodynamically stable children with traumatic liver and spleen injuries, nonoperative management has increasingly become the standard of care over the last few decades and is associated with decreased morbidity and mortality [33,34]. Despite the existence of several clinical practice guidelines for pediatric solid organ injury management, there are still varying degrees of familiarity with, and the reported use of, these guidelines among adult general surgeons compared with their pediatric counterparts [35,36]. Strategies to ensure the widespread adoption of spleen-conserving management are needed to optimize management of the hemodynamically stable pediatric patient with blunt abdominal trauma. For children without an identifiable IAI after blunt abdominal trauma, the disposition from the ED is less clear. The current practice in many trauma centers is to admit pediatric abdominal trauma patients for serial abdominal exams and laboratory measurements despite a normal ED abdominal CT, because of the possibility of missed or delayed IAI. A prospective observational study of 1085 children less than 18 years old with abdominal CT imaging after blunt abdominal trauma reported that 737 (68%) with normal ED abdominal CTs were admitted to the hospital. Only two of these children were subsequently diagnosed with IAI, neither of whom required acute intervention [37]. A review of three prospective observational studies (including the study discussed above) with a collective sample size of 2596 patients determined that the NPV of abdominal CT for diagnosing IAI was 99.8% (95% CI 99.3 100%) with the primary outcome of prevalence of IAI after a negative CT. Overall, there were five patients (0.19%) who required either a laparotomy or repeat abdominal CT after an initially negative abdominal CT, only one of whom required a surgical intervention to repair a bowel injury beyond 24 h of presentation. These studies suggest that routine hospital admission for serial abdominal exams and laboratory measurements after a normal abdominal CT scan and a normal physical exam may not be necessary [38 && ]. CONCLUSION Abdominal trauma continues to be a substantial cause of morbidity and mortality in children. CT imaging remains the gold standard for the diagnosis of IAI, but should be used judiciously due to the risk of radiation-induced malignancy. The FAST exam should not be used as the sole screening tool to rule out IAI, but may be used in conjunction with physical exam findings and laboratory results. The majority of children with a normal ED abdominal CT and normal physical exam may be discharged home with close follow up. Acknowledgements L.K.L. receives funding support from the Health and Human Services Department of Health Resources and Services Administration (HRSA, 1H34MC193530100) through the Pediatric Emergency Care Applied Research Network (PECARN). 1040-8703 ß 2012 Wolters Kluwer Health Lippincott Williams & Wilkins www.co-pediatrics.com 317

Emergency and critical care medicine Conflicts of interest There are no conflicts of interest. REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest Additional references related to this topic can also be found in the Current World Literature section in this issue (pp. 428 430). 1. National Center for Injury Prevention and Control: Web-based Injury Statistics and Query System (WISQARS). Centers for Disease Control and Prevention. http://www.cdc.gov/injury/wisqars. [Accessed 21 December 2011] 2. Bixby SD, Callahan MJ, Taylor GA. Imaging in pediatric blunt abdominal trauma. Semin Roentgenol 2008; 43:72 82. 3. Gaines BA. Intra-abdominal solid organ injury in children: diagnosis and treatment. J Trauma 2009; 67:S135 S139. 4. Paris C, Brindamour M, Ouimet A, St-Vil D. Predictive indicators for bowel injury in pediatric patients who present with a positive seat belt sign after motor vehicle collision. J Pediatr Surg 2010; 45:921 924. 5. Stacey S, Forman J, Woods W, et al. Pediatric abdominal injury patterns generated by lap belt loading. J Trauma 2009; 67:1278 1283. 6. Chidester S, Rana A, Lowell W, et al. Is the seat belt sign associated with serious abdominal injuries in pediatric trauma? J Trauma 2009; 67:S34 S36. 7. Karam O, La Scala G, Le Coultre C, Chardot C. Liver function tests in children with blunt abdominal traumas. Eur J Pediatr Surg 2007; 17:313 316. 8. Bevan CA, Palmer CS, Sutcliffe JR, et al. Blunt abdominal trauma in children: how predictive is ALT for liver injury? Emerg Med J 2009; 26:283 288. 9. Trout AT, Strouse PJ, Mohr BA, et al. Abdominal and pelvic CT in cases of suspected abuse: can clinical and laboratory findings guide its use? Pediatr Radiol 2011; 41:92 98. 10. Lindberg D, Makoroff K, Harper N, et al. Utility of hepatic transaminases to recognize abuse in children. Pediatrics 2009; 124:509 516. 11. Bahner D, Blaivas M, Cohen HL, et al. AIUM practice guideline for the performance of the focused assessment with sonography for trauma (FAST) examination. J Ultrasound Med 2008; 27:313 318. 12. American College of Surgeons Committee on Trauma. Pediatric Trauma. In: Advanced Trauma Life Support for Doctors. 8th ed. Chicago, IL: American College of Surgeons; 2008. p. 238. 13. Scaife ER, Fenton SJ, Hansen KW, Metzger RR. Use of focused abdominal sonography for trauma at pediatric and adult trauma centers: a survey. J Pediatr Surg 2009; 44:1746 1749. 14. Karam O, Sanchez O, Wildhaber BE, La Scala GC. National survey on abdominal trauma practices of pediatric surgeons. Eur J Pediatr Surg 2010; 20:334 338. 15. Dean AJ, Breyer MJ, Ku BS, et al. Emergency ultrasound usage among recent emergency medicine residency graduates of a convenience sample of 14 residencies. J Emerg Med 2010; 38:214 220. 16. Holmes JF, Gladman A, Chang CH. Performance of abdominal ultrasonography in pediatric blunt trauma patients: a meta-analysis. J Pediatr Surg 2007; 42:1588 1594. 17. && Fox JC, Boysen M, Gharahbaghian L, et al. Test characteristics of focused assessment of sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma. Acad Emerg Med 2011; 18:477 482. This large prospective study of pediatric blunt abdominal trauma determined test characteristics of the FAST for clinically important intraperitoneal free fluid, defined as moderate or greater amount of free fluid reported on the abdominal CT or presence of free fluid at surgery. In addition, test characteristics were also calculated for FAST to detect any amount of intraperitoneal free fluid, as measured on CT. 18. Sola JE, Cheung MC, Yang R, et al. Pediatric FAST and elevated liver transaminases: an effective screening tool in blunt abdominal trauma. J Surg Res 2009; 157:103 107. 19. Karam O, Sanchez O, Chardot C, La Scala G. Blunt abdominal trauma in children: a score to predict the absence of organ injury. J Pediatr 2009; 154:912 917. 20. Valentino M, Ansaloni L, Catena F, et al. Contrast-enhanced ultrasonography in blunt abdominal trauma: considerations after 5 years of experience. Radiol Med 2009; 114:1080 1093. 21. Valentino M, Serra C, Pavlica P, et al. Blunt abdominal trauma: diagnostic performance of contrast-enhanced US in children initial experience. Radiology 2008; 246:903 909. 22. Retzlaff T, Hirsch W, Till H, Rolle U. Is sonography reliable for the diagnosis of pediatric blunt abdominal trauma? J Pediatr Surg 2010; 45:912 915. 23. Sivit CJ. Abdominal trauma imaging: imaging choices and appropriateness. Pediatr Radiol 2009; 39:S158 S160. 24. Brenner DJ, Hall EJ. Computed tomography: an increasing source of radiation exposure. N Engl J Med 2007; 357:2277 2284. 25. Linet MS, Kim KP, Rajaraman P. Children s exposure to diagnostic medical radiation and cancer risk: epidemiologic and dosimetric considerations. Pediatr Radiol 2009; 39:S4 S26. 26. & Scaife ER, Rollins MD. Managing radiation risk in the evaluation of the pediatric trauma patient. Semin Pediatr Surg 2010; 19:252 256. This review article summarizes the arguments supporting and refuting the radiation risk associated with diagnostic imaging and discusses strategies for managing the radiation risk in the pediatric trauma patient. 27. & Cook SH, Fielding JR, Phillips JD. Repeat abdominal computed tomography scans after pediatric blunt abdominal trauma: missed injuries, extra costs, and unnecessary radiation exposure. J Pediatr Surg 2010; 45:2019 2024. This article highlights that abdominal CT scans are frequently repeated after a pediatric blunt trauma patient is transferred from a referring hospital to a trauma center, and, although some repeat scans are due to changes in clinical status, not all repeat scans are necessary. 28. Chwals WJ, Robinson AV, Sivit CJ, et al. Computed tomography before transfer to a level I pediatric trauma center risks duplication with associated increased radiation exposure. J Pediatr Surg 2008; 43:2268 2272. 29. Holmes JF, Mao A, Awasthi S, et al. Validation of a prediction rule for the identification of children with intra-abdominal injuries after blunt torso trauma. Ann Emerg Med 2009; 54:528 533. 30. Sivit CJ. Imaging children with abdominal trauma. AJR Am J Roentgenol 2009; 192:1179 1189. 31. Christiano JG, Tummers M, Kennedy A. Clinical significance of isolated intraperitoneal fluid on computed tomography in pediatric blunt abdominal trauma. J Pediatr Surg 2009; 44:1242 1248. 32. Letton RW, Worrell V. Delay in diagnosis and treatment of blunt intestinal injury does not adversely affect prognosis in the pediatric trauma patient. J Pediatr Surg 2010; 45:161 165. 33. Feigin E, Aharonson-Daniel L, Savitsky B, et al. Conservative approach to the treatment of injured liver and spleen in children: association with reduced mortality. Pediatr Surg Int 2009; 25:583 586. 34. Davies DA, Pearl RH, Ein SH, et al. Management of blunt splenic injury in children: evolution of the nonoperative approach. J Pediatr Surg 2009; 44:1005 1008. 35. Bowman SM, Bulger E, Sharar SR, et al. Variability in pediatric splenic injury care: results of a national survey of general surgeons. Arch Surg 2010; 145:1048 1053. 36. Sims CA, Wiebe DJ, Nance ML. Blunt solid organ injury: do adult and pediatric surgeons treat children differently? J Trauma 2008; 65:698 703. 37. Awasthi S, Mao A, Wooton-Gorges SL, et al. Is hospital admission and observation required after a normal abdominal computed tomography scan in children with blunt abdominal trauma? Acad Emerg Med 2008; 15:895 899. 38. && Hom J. The risk of intra-abdominal injuries in pediatric patients with stable blunt abdominal trauma and negative abdominal computed tomography. Acad Emerg Med 2010; 17:469 475. This article is a literature review of children with blunt abdominal trauma requiring an abdominal CT. It determined the prevalence of IAI after an initially negative CT. 318 www.co-pediatrics.com Volume 24 Number 3 June 2012