title: Test characteristics of focused assessment of sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma.
abstract: OBJECTIVE
  Focused assessment of sonography in trauma (FAST) has been shown useful to detect clinically significant hemoperitoneum in adults, but not in children. The objectives were to determine test characteristics for clinically important intraperitoneal free fluid (FF) in pediatric blunt abdominal trauma (BAT) using computed tomography (CT) or surgery as criterion reference and, second, to determine the test characteristics of FAST to detect any amount of intraperitoneal FF as detected by CT.
  
  
  METHODS
  This was a prospective observational study of consecutive children (0-17 years) who required trauma team activation for BAT and received either CT or laparotomy between 2004 and 2007. Experienced physicians performed and interpreted FAST. Clinically important FF was defined as moderate or greater amount of intraperitoneal FF per the radiologist CT report or surgery.
  
  
  RESULTS
  The study enrolled 431 patients, excluded 74, and analyzed data on 357. For the first objective, 23 patients had significant hemoperitoneum (22 on CT and one at surgery). Twelve of the 23 had true-positive FAST (sensitivity = 52%; 95% confidence interval [CI] = 31% to 73%). FAST was true negative in 321 of 334 (specificity = 96%; 95% CI = 93% to 98%). Twelve of 25 patients with positive FAST had significant FF on CT (positive predictive value [PPV] = 48%; 95% CI = 28% to 69%). Of 332 patients with negative FAST, 321 had no significant fluid on CT (negative predictive value [NPV] = 97%; 95% CI = 94% to 98%). Positive likelihood ratio (LR) for FF was 13.4 (95% CI = 6.9 to 26.0) while the negative LR was 0.50 (95% CI = 0.32 to 0.76). Accuracy was 93% (333 of 357, 95% CI = 90% to 96%). For the second objective, test characteristics were as follows: sensitivity = 20% (95% CI = 13% to 30%), specificity = 98% (95% CI = 95% to 99%), PPV = 76% (95% CI = 54% to 90%), NPV = 78% (95% CI = 73% to 82%), positive LR = 9.0 (95% CI = 3.7 to 21.8), negative LR = 0.81 (95% CI = 0.7 to 0.9), and accuracy = 78% (277 of 357, 95% CI = 73% to 82%).
  
  
  CONCLUSIONS
  In this population of children with BAT, FAST has a low sensitivity for clinically important FF but has high specificity. A positive FAST suggests hemoperitoneum and abdominal injury, while a negative FAST aids little in decision-making.
authors.affiliation: Department of Emergency Medicine and Department of Surgery (JCF, MB, SSA, CLA, ML, MIL), University of California at Irvine, Orange, CA. jchristianfox@gmail.com
authors.forename: J Christian
authors.initials: JC
authors.lastname: Fox
authors.forename: Megan
authors.initials: M
authors.lastname: Boysen
authors.forename: Laleh
authors.initials: L
authors.lastname: Gharahbaghian
authors.forename: Seric
authors.initials: S
authors.lastname: Cusick
authors.forename: Suleman S
authors.initials: SS
authors.lastname: Ahmed
authors.forename: Craig L
authors.initials: CL
authors.lastname: Anderson
authors.forename: Michael
authors.initials: M
authors.lastname: Lekawa
authors.forename: Mark I
authors.initials: MI
authors.lastname: Langdorf
mesh_terms: D000007:Abdominal Injuries / Q000150:complications / Q000000981:diagnostic imaging* / Q000601:surgery; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital; D005260:Female; D006465:Hemoperitoneum / Q000000981:diagnostic imaging* / Q000209:etiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007813:Laparotomy; D008297:Male; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards*; D014193:Trauma Centers; D014463:Ultrasonography / Q000379:methods / Q000592:standards*; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging*