Residency · Residency · Diagnostic Radiology

Non-Accidental Trauma: Imaging Findings and Reporting Obligations

Introduction

Non-accidental trauma (NAT), also termed child abuse, is a critical diagnosis that radiologists must recognize. Imaging findings are often the first evidence of abuse, and the radiologist has a legal and ethical obligation to report suspected cases. A thorough understanding of highly specific fracture patterns, intracranial injury, and visceral trauma is essential.

Epidemiology and Clinical Context

NAT is most common in children under 2 years of age. Risk factors include prematurity, disability, young or single parents, substance abuse, and socioeconomic stress. The history provided is often inconsistent with the severity or pattern of injury, and multiple injuries at different stages of healing are a hallmark finding. Delay in seeking medical care is a concerning feature.

Skeletal Survey

Protocol

The skeletal survey is the standard imaging evaluation for suspected NAT in children under 2 years. A complete series includes at least 20 views covering the entire skeleton: AP views of all extremities (humeri, forearms, femurs, tibiae and fibulae), hands, and feet, plus AP and lateral views of the axial skeleton (skull, spine, chest, pelvis). A follow-up skeletal survey at 2 weeks increases detection of occult fractures by 10-25%. A babygram (single whole-body image) is inadequate and should never replace a complete skeletal survey.

Highly Specific Fractures for NAT

Classic metaphyseal lesions (CMLs), also called corner fractures or bucket-handle fractures, occur at the metaphysis due to shearing forces and are highly specific for abuse. Posterior rib fractures result from squeezing the chest during shaking and are also highly specific. Scapular fractures are rare in accidental trauma and require significant force. Spinous process fractures indicate direct blows or forceful hyperflexion, and sternal fractures are uncommon in accidental pediatric trauma.

Moderately Specific Fractures

Moderately specific findings include multiple fractures at different stages of healing, bilateral fractures in a non-ambulatory child, complex skull fractures (bilateral, crossing sutures, diastatic), vertebral body fractures or subluxations, and epiphyseal separations and digital fractures in infants.

Intracranial Injury

Abusive Head Trauma (Shaken Baby Syndrome)

Subdural hematomas (SDH) are the most common intracranial finding in NAT. SDH of varying ages (mixed density on CT) suggests repeated episodes of trauma. Interhemispheric SDH along the falx is highly suspicious for NAT. Subarachnoid hemorrhage may accompany subdural collections, and retinal hemorrhages are present in 85% of cases and are best documented by ophthalmology.

Parenchymal Injury

Diffuse axonal injury (DAI) results from shearing forces during rotational acceleration-deceleration. Hypoxic-ischemic injury may occur due to apnea during shaking episodes. CT shows diffuse cerebral edema with loss of gray-white differentiation. MRI with diffusion-weighted imaging (DWI) is more sensitive for early ischemic changes and DAI, and SWI (susceptibility-weighted imaging) detects microhemorrhages not visible on CT.

Visceral Injury

Abdominal injuries in NAT carry the highest mortality rate. Characteristic findings include duodenal hematoma or perforation from a direct blow to the abdomen, pancreatic injury including transection or pseudocyst formation, hepatic and splenic lacerations or subcapsular hematomas, and hollow viscus perforation with free intraperitoneal fluid or pneumoperitoneum. CT with IV contrast is the modality of choice for evaluating visceral injuries.

Differential Diagnosis and Mimics

Several conditions can mimic NAT findings and must be considered. Osteogenesis imperfecta presents with multiple fractures along with osteopenia, blue sclerae, and wormian bones. Rickets causes metaphyseal fraying and cupping that should not be confused with CMLs. Menkes disease, a copper metabolism disorder, causes metaphyseal spurs and subdural hematomas. Birth trauma can cause clavicle and humeral fractures that heal within 2-3 weeks. Normal variants such as physiologic periosteal reaction in infants (symmetric, smooth, along the diaphysis) should also be recognized.

Reporting Obligations

Legal Requirements

All 50 US states mandate reporting of suspected child abuse by healthcare providers. Radiologists are mandatory reporters, and suspicion alone is sufficient grounds for reporting. Reports should be made to Child Protective Services (CPS) and/or law enforcement. Failure to report carries legal penalties including fines and potential criminal charges, while good faith reporters are protected from liability by law.

Documentation Best Practices

Radiologists should use objective, descriptive language in the radiology report and clearly state that findings are "concerning for" or "suspicious for non-accidental trauma." Definitive statements about the perpetrator or intent should be avoided. Documentation should include communication with the referring clinician and the time of notification. A follow-up skeletal survey at 2 weeks and an ophthalmologic examination should be recommended.

Clinical Pearls

Classic metaphyseal lesions and posterior rib fractures are the most specific skeletal findings for NAT. Multiple fractures at different stages of healing in a child under 2 should raise immediate concern. A follow-up skeletal survey at 2 weeks detects additional fractures in up to 25% of cases. Radiologists are mandatory reporters, and a good faith report based on imaging suspicion is both legally required and legally protected.

References

1. ACR Appropriateness Criteria: Suspected Physical Abuse in Children. J Am Coll Radiol. 2017;14(5S):S338-S349.
2. Classic Metaphyseal Lesion in Infants: A Systematic Review. Pediatr Radiol. 2018;48(11):1543-1555.
3. Abusive Head Trauma in Infants and Children. Radiographics. 2019;39(4):1064-1084.
4. The Role of Imaging in Child Abuse. Radiology. 2020;295(3):517-530.

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