You will see patients with blunt abdominal trauma in the Pediatric Emergency Department. It can be challenging to sort out which ones need imaging immediately vs which ones you can observe. I recommend that you all read Holmes et al, from Annals of Emergency Medicine in 2013. It details a large, multi center study of over 12,000 children with blunt torso trauma. Binary recursive partitioning was used to create a rule to identify children at very low risk of intra-abdominal injuries (IAI) that needed acute interventions (laparotomy, angiographic embolization, blood transfusion or intravenous fluid for ≥2 nights for pancreatic/gastrointestinal injuries). Ultimately only 6.3% (761/12,044) had IAI, and only roughly ¼ of these needed acute interventions (203/761).

In descending order of importance the prediction rule identified the following findings:

  • No evidence of abdominal wall trauma or seat belt sign
  • Glasgow Coma Scale score ≥ 13
  • No abdominal tenderness
  • No evidence of thoracic wall trauma
  • No complaints of abdominal pain
  • No decreased breath sounds
  • No vomiting
Statistically speaking the characteristics had:

  • Negative predictive value of 99.9% (95% CI 99.7% to 100%)
  • Sensitivity of 97% (95% CI 94% to 99%)
  • Specificity of 42.5% (95% CI 41.6% to 43.4%)
  • Negative likelihood ratio of 0.07 (95% CI 0.03 to 0.15)

Additionally, the risk of IAI increased with the number of predictors as noted in the following table.

from Holmes et al., Annals of Emerg Med, 2013

from Holmes et al., Annals of Emerg Med, 2013

A simple way to think about the workup of IAI in the trauma bay

  • Assessment for blunt IAI is a key part of the secondary survey (after the ABCs)
  • Hemodynamically unstable children unresponsive to isotonic  IV bolus and blood need a laparotomy.
  • Patients with multiple risk factors as noted above who are hemodynamically stable should undergo abdominal/pelvic CT with contrast
    • Note that FAST is less helpful diagnostically in children, as hemodynamically stable children with a positive FAST are much more likely need non-operative management as opposed to adults.
    • Hemodynamically unstable children (hypotensive, need >40 mL/kg of isotonic fluid) with a positive FAST should undergo diagnostic laparotomy
    • Children getting a CT should at least get a CBC and type and screen, ALT and AST.
  • Every patient should have a chest X-Ray in the trauma bay to look for pneumothorax and widened mediastinum. If either/both are seen and the patient is stable a chest CT should be considered (after interventions like chest tubes of course).
  • Hemodynamically stable with a reassuring exam, but concern for IAI (1 predictor from above like mild abdominal tenderness alone) should undergo lab testing and have serial abdominal exams. The labs include (along with likelihood of IAI if abnormal):
    • Hematocrit ≤30%     OR 2.6 (95% CI 0.9 to 7.5)
    • Urinalysis >5 RBCs/hpf     OR 4.8 (95% CI 2.7 to 8.4)
    • Transaminases – AST ≥200 U/L or ALT ≥125 U/L     OR 17.4 (95% CI 9.4 to 32.1)
    • Amylase >125 IU/L and elevated Lipase    Much less sensitive than the others, particularly amylase. Lipase in one study has a PPV of 75%
  • Other factors associated with elevated odds of IAI should prompt imaging as well. These include:
    • Low systolic blood pressure     OR 4.1 (95% CI 1.1 to 15.2)
    • Femur fracture     OR 1.3 (95% CI 0.5 to 3.7)

More reading

Borgialli et al. Association between the seat belt sign and intra-abdominal injuries in children with blunt torso trauma in motor vehicle collisions Academic Emergency medicine, 2014.