Clinical indications for CT angiography in lower extremity trauma

Abstract

Background: Missed vascular injuries in lower extremity trauma may lead to a preventable lower extremity amputation. CT angiography (CTA) is an accurate and expedient, but costly and potentially harmful, test for vascular injury in lower extremity trauma. Specific physical examination findings and injury patterns may be predictive of detection of a vascular injury by CTA and could guide CTA use in lower extremity trauma. Methods: This was a retrospective review of consecutive trauma patients at an academic level 1 trauma center who underwent CTA of a lower extremity from January 2006 through December 2012. The positive predictive values of injury pattern and physical examination signs for CTA detection of a vascular injury and vascular intervention, adherence to published guidelines for CTA use, and CTA-related adverse events were assessed. Results: Diagnostic CTA studies demonstrated a vascular injury in 55.6%. A vascular intervention followed in 13.9%, while 5.6% of studies led to a contrast-related adverse event. The positive predictive value of a CTA affecting treatment was significantly higher in the presence of high-risk injuries and hard examination findings than in the presence of low-risk injuries and soft examination findings (84.6%, 95% CI [54.6–98.1%] vs. 16.7%, 95% CI [3.6–41.1%]). Palpable pulses and ankle brachial index (ABI)>0.9 led to observational management without complications, regardless of CTA findings or other signs of vascular injury. Conclusions: The utility of CTA is improved by assessing the pretest positive predictive value of vascular injury from injury pattern and physical examination. The Eastern Association for the Surgery of Trauma guidelines may miss some vascular injuries in patients with high-risk injuries and normal ABI. CTA is not indicated in lower extremity trauma when physical examination and injury pattern do not suggest a vascular injury.