Low Risk Intra-Abdominal Trauma: Rebaked Morsel

Evaluation of unintentional injury and trauma is one of the hallmarks of the EM and PEM physician. One of the most difficult and most satisfying parts of pediatric emergency medicine is using one’s history, exam and clinical tools to make an informed decision and spare children from unnecessary pain, uncomfortable exams, painful procedures and medical imaging. Today we tackle low risk intra-abdominal injury, to find those children in which less may be more. 

Low Risk Inta-Adbominal Trauma: Pediatric Trauma is Dangerous!

• Unintentional injuries are the leading cause of death in children.
• In 2009, more than 9,000 children died from accidental injuries.
• Every hour, 1 child dies from an injury.
• Intra-Abdominal trauma is the third most common cause of mortality in trauma for children, but it is the number one cause of death in initially unrecognized trauma.

Low Risk Inta-Adbominal Trauma: Just Light ‘Em Up? 

As it turns out, the donut of truth can be the donut of danger for our pediatric population. Children are at high risk from medical radiation due to:

• Rapidly growing tissues that are more sensitive to ionizing radiation
• Higher doses of radiation per scan due to thinner torsos and hence, less shielding of intra-abdominal organs
• More time to accumulate radiation-associated malignancies when compared to their adult counterparts
  • A single abdominal CT scan increases the lifetime attributable risk of dying from cancer by 0.14% if done on an infant.
  • A radiation-induced solid cancer is projected to result from every 300-390 CT of the abdomen and pelvis in girls and every 670-760 CTs in boys.

It should come as no surprise that the PEM profession has been trying to find an effective way to avoid abdominal CT scans in trauma for quite some time. Thanks to the recently completed, prospective external validation of the PECARN Pediatric Intra-abdominal Injury (IAI) Rule, we may have an addition tool in this quest. 

Low Risk Intra-Abdominal (IAI) Trauma – Derivation of the Rule

The PECARN Group first released their derivation of a pediatric prediction rule for intra-abdominal injury in 2013. Cohort of 12,000 children with blunt IAI were prospectively enrolled to determine the number of subjects requiring acute intervention .

• Primary outcome was death or acute intervention:
  • Therapeutic intervention at laparotomy
  • Angiographic embolization of intra-abdominal bleeding 
  • Blood transfusion for IAI
  • Administration of IVF for 2 or more nights in patients with pancreatic or GI injuries
• The group found 7 factors associated with an increased risk of IAI requiring acute intervention, with the associated percentage requiring intervention for each variable.
  • Evidence of abdominal wall trauma or abdominal seatbelt sign (5.7%)
  • GCS <14 (4.6%)
  • Abdominal Tenderness on exam (1.4%)
  • Thoracic wall trauma (0.6%)
  • Complaint of abdominal pain (0.7%)
  • Decreased breath sounds (2.9%)
  • Vomiting (0.5%)
• This could allow risk stratification without use of labs or diagnostic imaging.
• Only 6 patients classified as very low risk were found to have IAI requiring intervention.
  • 5 of 6 had abnormalities in lab values (hematuria, elevated liver transaminase levels) and 6 of 6 had hemoperitoneum.
• 46% of the study population received an abdominal CT scan. 23% of these were performed in children who were very low risk. This led the authors to infer that radiation would be spared if this rule were to be the standard.
• If all patients with a score of 1 were scanned, 53% of the study participants would’ve had an abdominal CT. This concerned clinicians.

IAI Rule – The Validation

• A multicenter prospective validation was planned at hospitals distinct from those where the initial derivation was performed.
• 7542 children were enrolled and the PECARN IAI Rule was applied by the bedside attending physician. 
• Correctly identified patients as “not very low risk” in 145/145 injuries requiring acute intervention. There were no missed injuries.
  • Sensitivity and NPV of 100%. 
• Inter-rater reliability was assessed, and raw agreement was 85% (k 0.690).

Low Risk Intra-Abdominal (IAI) Trauma: Putting it All Together

• It is very important to remember, with any decision rule, to determine if your patient meets inclusion criteria to be risk stratified.
• The PECARN IAI Rule only included those with high risk mechanisms of injury:
  • Blunt torso trauma from major mechanism
  • MVC exceeding 96 km/hr, with ejection or with rollover
  • Auto-Ped or Auto-Bicycle with speed > 40 km/hr
  • Fall from > 6 meters
  • Crush injury of torso
  • Physical Assault, including abdomen
  • Decreased LOC (GCS < 15) with torso trauma
  • Blunt trauma with limb paralysis or multiple long bone fractures
  • Exam suggestive of intra-abdominal trauma following blunt torso trauma

• Not all patients with a score of 1 (IAI requiring intervention risk 0.7%) need a scan. Incorrect interpretation of the recommendations would lead to a very high number of CT scans.
• Clinicians can further risk stratify by:
  • FAST ExamSerial abdominal exams 
  • Laboratory studies:
  • AST >200 U/LALT > 125 U/L
  • Hematuria (>5 RBCs/hpf)
  • Initial hematocrit <30%

Moral of the Morsel

• Trauma Hurts us All! Trauma is one of the leading causes of death in children 0-18 years.
• Radiation deserves consideration. Ionizing radiation is not without risk and kids have a higher risk of cancer due to their cellular physiology, size and relatively longer time to absorb radiation.
• Use your Tools Wisely! The PECARN IAI Rule is a highly sensitive rule that can be used to determine children at very low risk for intra-abdominal injury, but prediction rules are not a surrogate for proper history, exam and clinical judgement.
• Use all your Tools Wisely! POCUS, Labs, and Urinalysis can be used to decrease the need for CT scan in certain patients who are not very low risk for IAI.

Sources

Adelgais KM, Kuppermann N, Kooistra J, et al. Accuracy of the Abdominal Examination for Identifying Children with Blunt Intra-Abdominal Injuries. J Pediatr. 2014;165:1230-1235. doi:10.1016/j.jpeds.2014.08.014.

Brenner DJ, Hall EJ. Computed Tomography — An Increasing Source of Radiation Exposure. N Engl J Med. 2007 Nov 22;357:2277-2284.

Holmes JF, Lillis K, Monroe D, et al. Identifying Children at Very Low Risk of Clinically Important Blunt Abdominal Injuries. Ann Emerg Med. 2013;62:107-116. doi:10.1016/j.annemergmed.2012.11.009.

Holmes JF, Yen K, Ugalde IT, et al. PECARN prediction rules for CT imaging of children presenting to the emergency department with blunt abdominal or minor head trauma: a multicentre prospective validation study. Lancet Child Adolesc Health. 2024;8:339-344.

Miglioretti DL, Johnson E, Williams A, et al. Pediatric Computed Tomography and Associated Radiation Exposure and Estimated Cancer Risk. JAMA Pediatr. 2013 Aug 1;167(8):700-707. doi:10.1001/jamapediatrics.2013.311.

Streck CJ, Vogel AM, Zhang J, Huang EY, Santore MT, Tsao K, Falcone RA, Dassinger MS, Russell RT, Blakely ML. Identifying Children at Very Low Risk for Blunt Intra-Abdominal Injury in Whom CT of the Abdomen Can Be Avoided Safely. J Am Coll Surg. 2017;224:449-460. doi:10.1016/j.jamcollsurg.2016.12.041.