Wednesday, September 3, 2014

Blunt Abdominal Trauma in Pediatric Patients: A Clinical Decision Rule

A school-age child was brought to the ED by the mother following involvement in an MVC during which the child was restrained with a lap belt.  The child initially complained of abdominal pain while eating, but currently has no complaints, stable vital signs, and a benign abdominal exam.  The mother is concerned and wonders if her child should get imaging.  This prompts you to investigate whether there are any evidence based clinical decision rules for imaging in pediatric blunt abdominal trauma.

Clinical question: 

Do all children with blunt abdominal trauma necessitate abdominal imaging?  Is there a clinical decision rule that can help guide physician and parent shared-decision making when weighing risks vs benefit in evaluation of pediatric patients following blunt abdominal trauma?

Literature:

Injuries secondary to blunt abdominal trauma contribute to a large degree of morbidity in the pediatric patient population.  In assessing these patients following trauma, CT scans have become the reference standard for diagnostic of traumatic injury.  However, we must also weigh the risk of exposing patients to increased dosage of radiation and increasing their risk of radiation-induced malignancy.  This is especially true in the pediatric population given their rapidly developing bodies as well as their propensity to have a continued lifetime of exposure to medical radiation through future diagnostics.  

Clinicians, especially those not accustomed to regularly seeing pediatric patients, trauma patients, or more specifically pediatric trauma patients, often (anecdotally) err on the side of obtaining advanced imaging to assess patients following blunt abdominal trauma.  Dr. James Holmes and his colleagues in the PECARN (Pediatric Emergency Care Applied Research Network) group derived a clinical decision rule to help guide decision making when considering imaging in the pediatric patients.  Using a large, prospective study in 20 EDs, they identified a 7 point rule based solely on history and physical data to help risk stratify the pediatric blunt abdominal patient.  In patients who have no evidence of abdominal wall trauma or a seatbelt sign, a GCS >14, no abdominal tenderness on PE, no thoracic wall trauma, no complaint of abdominal pain, no absence or decreased breath sounds, and no vomiting, the risk of intra-abdominal injury requiring intervention is extremely low (0.1%).  

While these findings require external validation before likely widespread use, they have benefit for current ED practitioners for several reasons.  First, they used a patient oriented outcome of injury requiring intervention rather than a diagnostic outcome of any intra-abdominal injury, so that some patients who perhaps had injury but went on to have a stable clinical course and never received imaging were not a source of bias.  Secondly, their 7 findings were based solely on history and physical findings, something that is available to any clinician regardless of location or resources.  This eliminated the exclusion of validity to centers able to perform FAST scans or obtain more rapid lab results.  It also likely further decreased the “miss rate” for significant intra-abdominal injury when the clinical decision rule is supplemented by these diagnostic studies.  Finally, their rule is not meant as a hard “rule” to force a physician’s hand in obtaining a CT on a patient who carries 1 or 2 of their H&P risk factors.  It is meant to guide the conversation and critical decision process in weighing the radiation exposure risk versus the inherent injury risk when deciding how to continue the workup of the presenting child.  0.1% is a lower risk of injury the risk of a radiation induced malignancy in a young child.  However, as more risk factors accumulate, that may mitigate the difference in risk percentage, increasing the possible benefit of obtaining the CT.

Take home:

All patients, especially pediatric patients are sensitive to the ionizing radiation of medical imaging.  Risk stratifying pediatric patients with decreased likelihood of significant intra-abdominal injury can help physicians to have informed discussions with patients and their guardians and help to decrease the number of CT scans ordered on low risk patients and their exposure to unnecessary radiation.

References:

1) Holmes, JF, et al.  Identifying Children at Very Low Risk of Clinically Important Blunt Abdominal Injuries.  Annals of Emergency Medicine.  2013. 62: 107-16

Kindly contributed by Michael Galante, PGY-3.

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