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 trauma care. Clinical Question: What is the risk for intraabdominal injuries requiring acute intervention (IAIAI) in children with one or two positive PECARN intraabdominal injury rule variables? 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 Population: Children <18 years with blunt torso trauma Excluded: Injury occurring >24 hours before ED presentation, penetrating trauma, pre-existing neurological disorder preventing reliable abdominal exam, pregnancy, transfer from another hospital with prior abdominal imaging. All patients who were negative for the original PECARN prediction rule or had more than two variables present. Intervention: Application of the PECARN intraabdominal injury prediction rule with one or two positive variables Comparison: None Outcome: Primary Outcome: Intraabdominal injury undergoing acute intervention (death caused by IAI, therapeutic laparotomy, angiographic embolization, blood transfusion, or ≥2 nights of IV fluids). Secondary Outcomes: Any intraabdominal injury (injuries to the liver, spleen, urinary tract, gastrointestinal tract, pancreas, gallbladder, adrenals, vasculature, or fascial defects).  Trial: Planned secondary analysis of a prospective multicenter observational study Authors’ Conclusions: “Few children with blunt torso trauma and one or two PECARN predictor variables present have IAIAI. Those with GCS score <14, however, are at highest risk for IAI.” Quality Checklist for Clinical Decision Rules: Did the study population include or focus on those in the emergency department? Yes Where was the study conducted (external validity)? Six emergency departments in the United States Were the patients included in the study representative of those with the problem? Yes Were all important predictor variables and outcomes explicitly specified? Yes Is this a prospective, multicenter study including a broad spectrum of patients and clinicians (Level II study)? Yes Did clinicians interpret individual predictor variables and score the clinical decision rule reliably and accurately? Unsure (not detailed clearly in the abstract) Is this an impact analysis of a previously validated clinical decision rule (Level I study)? No For a Level I study, was the impact on clinician behavior and patient-centric outcomes reported? N/A Was the follow-up sufficiently long and complete? Yes Was the effect large enough and precise enough to be clinically significant? Yes Who funded the trial? Eunice Kennedy Shriver National Institute of Child Health and Human Development Did the authors declare any conflicts of interest? No conflicts declared Results: The original study included 7,542 children with blunt torso trauma across six emergency departments. Of those children, 2,986 (39.6%, 95% CI 38.5 to 40.7) had one or two PECARN positive variables. The median age was 9.8 years and slightly over half (56%) were male. CT scans were obtained in 1236 (41%) of the patients. Key Results: Few children with one or two positive PECARN rule variables had IAI, with the highest risk in those with GCS <14. The presence of isolated abdominal pain, vomiting, or tenderness was not associated with IAI. Primary Outcome: Of the 1,639 patients who had one variable positive, 21 (1.3%, 95% CI 0.8-2) had intra-abdominal injuries undergoing acute intervention. Of the 1347 who had two variables positive, 27 (2%, 95% CI 1.3-2.9) had intra-abdominal injuries undergoing acute intervention. Secondary Outcome: Of those 2986 patients enrolled, 227 (7.6%, 95% CI 6.7-8.6) had intra-abdominal injuries. They also broke it down by each individual variable and how many patients were diagnosed with intra-abdominal injury and intra-abdominal injury undergoing acute intervention. GCS≤14 was the most important individual predictor variable for intra-abdominal injury undergoing acute intervention. Inclusion Criteria: It’s important to review the inclusion criteria from the original study because we do not think this clinical decision rule should be applied indiscriminately to every child with abdominal trauma. A large proportion of the children included in the original study had some pretty severe mechanisms of injury (32% from motor vehicle collisions, 19% were struck by a vehicle, and 13% due to fall from height. Be careful in applying this clinical decision tool to less severe mechanisms. They excluded patients who had injury that occurred over 24 hours ago. Many of us may have encountered a patient in the emergency department who complains of belly pain from a blunt abdominal injury a day ago and were perhaps seen at an urgent care facility or tried to wait it out. Although they were not part of the patient population in this study, would it be inappropriate to use this clinical decision tool on those patients? Partial Verification Bias: In this secondary analysis, only around 40% of patients included had CT scans. What about those who did not? In the original derivation study, there was one patient with a splenic laceration who returned after being discharged from the ED without imaging who underwent splenic artery embolization. It is possible that some of these patients who did not undergo CT scan still had intra-abdominal injuries that were missed. This does highlight the primary outcome that they defined as IAI undergoing acute intervention. It is arguably more patient oriented, they missed some IAI but maybe it was not clinically significant. I’ve admitted low grade splenic or liver laceration to the hospital who were observed without any intervention except a repeat hemoglobin before being sent home. Spectrum Bias: