SGEM #479: Light Em Up Up Up (CT) or Not for Pediatric Blunt Abdominal Trauma?

Reference: Arnold CG, et al. Performance of individual criteria of the Pediatric Emergency Care Applied Research Network (PECARN) intraabdominal injury prediction rule. Acad Emerg Med. Jan 2025 Date: May 7, 2025 Dr. Sandi Angus Guest Skeptic : Dr. Sandi Angus is a Paediatric and Adult Emergency Medicine Registrar in the Shrewsbury and Telford Hospital NHS Trust. She is passionate about paediatric EM, wellbeing and medical education. Case: A ten-year-old boy presents to your emergency department (ED) after being involved in a motor vehicle collision at high speed. Emergency Medical Service (EMS) tells you that he was properly restrained. His parents were also in the vehicle and are currently being brought to the ED as well. He appeared a bit dazed initially, but he has had a Glasgow Coma Scale (GCS) score of 15 throughout transport. Your primary survey is unremarkable. He complains of some abdominal pain, although you note a soft abdomen on exam and no seatbelt sign. As you complete your secondary survey, he vomits once, which is non-bloody. A medical trainee working with says to you, “He says his stomach hurts and threw up. Do you think we need to CT scan his abdomen?” Background: Intra-abdominal injury (IAI) in children is a significant concern for emergency physicians. This is particularly true in cases of blunt trauma. Although relatively uncommon compared to adults, IAIs in children can be life-threatening. We have to identify them early and manage them appropriately. The organs most frequently injured include the spleen, liver, and kidneys, but any abdominal organ can be affected​. Diagnosing IAIs in pediatric patients poses a unique challenge. Children often present with subtle clinical findings, and the physical examination can be unreliable due to factors such as altered mental status, distracting injuries, or the child’s inability to articulate their symptoms​. Imaging modalities like computed tomography (CT) are the gold standard for diagnosis, but CT use must be balanced against the risks of ionizing radiation. Traditionally, clinicians relied heavily on their clinical gestalt, but this approach can miss injuries or lead to unnecessary imaging. The risks of CT imaging are not inconsequential. Children are more radiosensitive than adults, and for each  abdominal or pelvic scan, the lifetime risks of cancer are 1 per 500 scans, irrespective of the age at exposure. However, this is actually very small compared with the background risk of developing cancer in a lifetime, which is 1 in 3, so if your scan is clinically justified, the benefit is likely to outweigh the potential harm [1]. To improve diagnostic accuracy and minimize unnecessary CT scans, clinical decision rules (CDRs) or “tools” have been developed. One such tool, the Pediatric Emergency Care Applied Research Network (PECARN) clinical prediction rule for intra-abdominal injuries, identifies children at very low risk of clinically important IAIs, aiming to safely reduce CT utilization​ [2-3]. This rule was composed of seven variables, all of which could be collected on history and physical exam. There was no need for labs or imaging in this decision rule. These seven variables were: Evidence of abdominal wall trauma or seat belt sign GCS <14 and blunt abdominal trauma Abdominal tenderness Thoracic wall trauma Complaint of abdominal pain Decreased breath sounds Vomiting If all seven variables were negative, the child was at very low risk of having intra-abdominal injury requiring intervention and the decision rule recommended against a CT scan. Despite the benefits of existing decision rules, the question remains how best to apply these tools when only one or two PECARN criteria are positive—a clinical gray zone not well characterized in earlier validation studies. Understanding the individual performance of PECARN rule components in predicting IAI is crucial for refining decision-making in pediatric t...