ULTRASOUND CASE REVIEW Associate Editor: Jennifer R. Marin, MD, MSc

False-Positive Focused Abdominal Sonography in Trauma in a Hypotensive Child Case Report Isabelle Imamedjian, BScN,* Robert Baird, MDCM, MSc, FRCSC,† and Alexander Sasha Dubrovsky, MDCM, MSc, FRCPC‡

Abstract: We report a case of a false-positive focused abdominal sonography in trauma (FAST) examination in a persistently hypotensive pediatric trauma patient, performed 12 hours after the trauma, suspected to be caused by massive fluid resuscitation leading to ascites. While a positive FAST in a hypotensive trauma patient usually indicates hemoperitoneum, this case illustrates that the timing of the FAST examination relative to the injury, as well as clinical evolution including the volume of fluid resuscitation, need to be considered when interpreting the results of serial and/or late FAST examinations. Key Words: FAST, blunt abdominal trauma, resuscitation, abdominal compartment syndrome (Pediatr Emer Care 2015;31: 451–453)

CASE A 6-year-old girl sustained widespread blunt and penetrating trauma after being mauled by a pack of dogs. On arrival at the local hospital, she had a Glasgow Coma Scale score of 8, oxygen saturation of 86%, respiration rate of 20 breaths per minute, heart rate of 120 beats per minute, blood pressure of 107/52 mm Hg, and a core temperature of 35.3°C with an estimated weight of 20 kg. After intubation, trauma survey revealed a large scalp degloving injury, a right pneumothorax, and widespread lacerations. After a chest tube was placed and the scalp injury tamponaded, she was resuscitated with 1 L of normal saline, 2 units of packed red blood cells, and 1 units of fresh frozen plasma. Despite these measures, she remained in severe mixed metabolic and respiratory acidosis that did not improve with positive pressure ventilation and a bicarbonate drip. She subsequently went into cardiac arrest requiring 5 minutes of chest compressions, defibrillation, and 2 doses of epinephrine. While awaiting air medevac, she received 2 additional liters of normal saline. She arrived at the referral center 12 hours after the attack, intubated with an oxygen saturation of 80%, a heart rate of 130 beats per minute, and a blood pressure of 75/40 mm Hg that dropped to 50/20 mm Hg within minutes. Fluid resuscitation with normal saline was started and the massive transfusion protocol was initiated; she received 2 units of packed red blood cells and 1 units of cryoprecipitate, and owing to the persistent hypotension despite considerable volume resuscitation, vasopressor infusions were started. From the *Faculty of Medicine, McGill University; and †Departments of Pediatric Surgery and ‡Pediatric Emergency Medicine, Montreal Children's Hospital-McGill University Health Center, Montreal, Quebec, Canada. Disclosure: The authors declare no conflicts of interest. Reprints: Alexander Sasha Dubrovsky, MDCM, MSc, FRCPC, Pediatric Emergency Medicine, Montreal Children's Hospital-McGill University Health Center, 1001 Decarie Boulevard, Montreal, Quebec, Canada, H4A 3J1 (e‐mail: [email protected]). Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0749-5161

At this time, note was made that the patient's abdomen was bruised, multiple bite marks and contusions of the abdominal wall along with a distended albeit soft abdomen on palpation; the trauma team considered intra-abdominal injury as a possible cause for the persistent hypotension. A focused abdominal sonography in trauma (FAST) examination was performed and demonstrated a surprisingly large amount of intraperitoneal free fluid (Fig. 1). However, the presence on strong peripheral pulses and normal capillary refill seemed out of keeping with hemorrhagic shock. To guide further decision making, a diagnostic peritoneal lavage was performed, which revealed serous fluid without evidence of hemorrhage. The patient's hypotension improved shortly after the diagnostic peritoneal lavage. A whole body computed tomography was then performed and revealed a large amount of free intra-abdominal fluid with no evidence of intra-abdominal solid or hollow-viscus injuries and a small pneumothorax with bilateral pleural effusions. No other injuries were identified. She was transferred to the pediatric intensive care unit with stable vital signs and has since made a full recovery.

ULTRASOUND FINDINGS Large amount of intra-abdominal free fluid was seen on FAST examination, demonstrated by anechoic areas at the hepato-renal and spleno-renal interfaces (arrows), as well as the anechoic area encircling the spleen (stars).

TECHNIQUE A pediatric emergency medicine physician, certified as an independent practitioner by the Canadian Emergency Ultrasound Society standards,1 performed the FAST examination with the z. one ultra system (Zonare, Mountain View, Calif ) using a C6-2 curved array transducer. The standard abdominal views were obtained and included the right upper quadrant (Morison's pouch), the left upper quadrant (perisplenic space), pelvic (Pouch of Douglas), and the subxiphoid view (pericardium).

REVIEW OF THE LITERATURE Focused abdominal sonography in trauma has become the mainstay of imaging in the initial evaluation of trauma patients, replacing diagnostic peritoneal lavages in adult patients, because it rapidly guides management toward immediate laparotomy or further imaging by computed tomography scan.2 Studies have demonstrated that FAST has an excellent specificity and modest sensitivity in detecting hemoperitoneum in pediatric patients2–15 and performs with better accuracy in the hypotensive patient14 and when used serially.6,16–18 Studies to date have reported false-positive FAST results attributable to physiologic free fluid in girls, 4,6,7 incorrect interpretation,13 or perinephric fat pad.19 While the presence of intra-abdominal free fluid in the unstable trauma patient is usually indicative of hemorrhage, this case illustrates a false-positive FAST examination in this setting.

Pediatric Emergency Care • Volume 31, Number 6, June 2015

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Pediatric Emergency Care • Volume 31, Number 6, June 2015

FIGURE 1. Focused abdominal sonography in trauma examination revealed a large amount of intra-abdominal free fluid. Arrows demonstrate anechoic fluid at the hepato-renal (A) and the spleno-renal (B) interfaces; stars show free fluid encircling the spleen.

There has been mounting evidence that unrestricted use of crystalloids in resuscitation is associated with adverse outcomes in many patient populations, including pediatric and blunt trauma patients, due to worsening acidosis, local endothelial damage, volume overload leading to dilutional coagulopathy, and triggering of an inflammatory response. 20–23 In their study, Kasotakis et al20 noted a dose-dependent increased incidence of abdominal compartment syndrome in adult trauma patients who received liberal crystalloid administration ranging from 0% in patients who received less than 5 L to 12.1% in those who received more than 15 L. In fact, this case illustrates a possible secondary abdominal compartment syndrome as a result of massive fluid resuscitation (250 cc/kg of fluids administered) causing ascites, which then impaired respiratory and cardiac function. 24–26 The World Society of Abdominal Compartment Syndrome's diagnostic criteria suggest that the patient have 2 or more risk factors and an intraabdominal pressure measured more than 12 mm Hg for diagnosis. 26,27 In this instance, albeit no intra-abdominal pressure measurement was obtained, there were several risk factors (the abdominal free fluid seen on FAST and massive fluid resuscitation). The authors postulate that the diagnostic peritoneal lavage may have served as a therapeutic paracentesis, relieving the pressure from the ascites, effectively treating the syndrome. In keeping with this, the patient's physiologic parameters immediately improved after the procedure.

CONCLUSIONS While a positive FAST in the context of a persistently hypotensive trauma patient is usually indicative of intra-abdominal hemorrhage in need of urgent laparotomy, emergency department teams must consider the overall clinical picture and evolution of the resuscitation, as well as the timing of the examination relative to the injury, to guide decision making. The positive FAST examination in this 6-year-old trauma patient was not due to hemorrhage but to ascites secondary to massive fluid resuscitation. REFERENCES 1. Canadian Emergency Ultrasound Society. Recommended standards. Available at: http://ceus.ca/002-standards/002-00.standards.htm. Accessed February 25, 2014. 2. Stengel D, Bauwens K, Sehouli J, et al. Emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma. Cochrane Database Syst Rev. 2005;18:CD004446. 3. Katz S, Lazar L, Rathaus V, et al. Can ultrasonography replace computed tomography in the initial assessment of children with blunt abdominal trauma? J Pediatr Surg. 1996;31:649–651.



4. Souddapan SV, Holland AJ, Cass DT, et al. Diagnostic accuracy of surgeon-performed focused abdominal sonography (FAST) in blunt pediatric trauma. Injury. 2005;36:970–975. 5. Thourani VH, Pettitt BJ, Schmidt JA, et al. Validation of surgeon-performed emergency abdominal sonography in pediatric trauma patients. J Pediatr Surg. 1998;33:323–328. 6. Richards JR, Knopf N, Wang L, et al. Blunt abdominal trauma in children: evaluation with emergency US. Radiology. 2002;222:749–754. 7. Soudack M, Epelman M, Maor R, et al. Experience with focused abdominal sonography for trauma (FAST) in 313 pediatric patients. J Clin Ultrasound. 2004;32:53–61. 8. Friedman L, Tsung J. Extending the focused abdominal sonography for trauma examination in children. Clin Pediatr Emerg Med. 2011; 12:2–17. 9. 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. 10. Scaife ER, Fenton SJ, Hansen KW, et al. Use of focused abdominal sonography for trauma at pediatric and adult trauma centers: a survey. J Pediatr Surg. 2009;44:1746–1749. 11. Melniker LA, Leibner E, McKenney MG, et al. Randomized controlled clinical trial of point-of-care, limited ultrasonography for trauma in the emergency department: the first sonography outcomes assessment program trial. Ann Emerg Med. 2006;48:227–235. 12. Fox JC, Boysen M, Gharahbaghian L, et al. Test characteristics of focused abdominal sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma. Acad Emerg Med. 2011;18: 477–482. 13. Corbett SW, Andrews HG, Baker EM, et al. ED evaluation of the pediatric trauma patient by ultrasound. Am J Emerg Med. 1998;18:244–249. 14. Holmes JF, Brant WE, Bond WF, et al. Emergency department ultrasonography in the evaluation of hypotensive and normotensive children with blunt abdominal trauma. J Pediatr Surg. 2001;36:968–973. 15. Suthers SE, Albrecht R, Foley D, et al. Surgeon-directed ultrasound for trauma is a predictor of intra-abdominal injury in children. Am Surg. 2004; 70:164–167. 16. Porter RS, Nester BA, Dalsey WC, et al. Use of ultrasound to determine need for laparotomy in trauma patients. Ann Emerg Med. 1997;29: 323–330. 17. Nordenholz KE, Rubin MA, Gularte GG, et al. Ultrasound in the detection and management of blunt abdominal trauma. Ann Emerg Med. 1997;29:357–366. 18. Henderson SO, Sung J, Mandavia D. Serial abdominal ultrasound in the setting of trauma. J Emerg Med. 2000;18:79–81.

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Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.

Pediatric Emergency Care • Volume 31, Number 6, June 2015

False-Positive FAST in a Hypotensive Child

19. Sierzenski PR, Schofer JM, Bauman MJ, et al. The double line sign: a false positive finding on the Focused Abdominal with Sonography for Trauma (FAST) examination. J Emerg Med. 2011;40:188–189.

24. Ameloot K, Gillebert C, Desie N, et al. Hypoperfusion, shock states, and abdominal compartment syndrome (ACS). Surg Clin North Am. 2012; 92:207–220.

20. Kasotakis G, Sideris A, Yang Y, et al. Aggressive early crystalloid resuscitation adversely affects outcomes in adult blunt trauma patients: an analysis of the Glue Grant database. J Trauma Acute Care Surg. 2013;74:1215–1221.

25. De Wolf A, Poelaert J, Herck I, et al. Surgical decompression for abdominal compartment syndrome after emergency cardiac surgery. Ann Thorac Surg. 2008;85:2133–2135.

21. Alam HB, Rhee P. New developments in fluid resuscitation. Surg Clin North Am. 2007;87:55–72.

26. Malbrain M, Cheatham M. Definitions and pathological implications of intra-abdominal hypertension and abdominal compartment syndrome. Am Surg. 2011;77:S6–S11.

22. Cotton BA, Guy JS, Morris JA Jr, et al. The cellular, metabolic, and systemic consequences of aggressive fluid resuscitation strategies. Shock. 2006;26:115–121. 23. Bouchard J, Mehta RL. Fluid balance issues in the critically ill patient. Contrib Nephrol. 2010;164:69–78.

27. World Society of Abdominal Compartment Syndrome Web site. Intra-abdominal hypertension assessment algorithm. 2007. Available at: https://www.wsacs.org/resources/algorithms/IAH_algorithm.pdf. Accessed August 10, 2013.

© 2015 Wolters Kluwer Health, Inc. All rights reserved.

Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.



False-positive focused abdominal sonography in trauma in a hypotensive child: case report.

We report a case of a false-positive focused abdominal sonography in trauma (FAST) examination in a persistently hypotensive pediatric trauma patient,...
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