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Written by Chris Thom
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Prehospital eFAST exams performed on severely injured blunt trauma patients had high specificity for injury detection, while sensitivity was low.
Are prehospital eFAST exams helpful?
This retrospective study evaluated the test characteristics of eFAST examinations performed by emergency physicians in the pre-hospital environment. Patients being transported to four hospitals in France were the study subjects. Inclusion criteria were age older than 13 years and admission to the ICU following blunt trauma. Patients were excluded if the eFAST was inconclusive or if they died before hospital admission. Four hundred and ninety-five patients who received an eFAST examination in the prehospital environment were included. The sensitivity of the prehospital eFAST for the presence of any abdominal injury on CT scan was 27% (95%CI 22-32), while the specificity was 96% (95%CI 93-98). Sensitivity for hemoperitoneum was 38% (95%CI 28-48), with specificity of 94% (95%CI 91-96). Sensitivity for pneumothorax was 23% (95%CI 17-31), with specificity of 97% (95%CI 95-99).
How will this change my practice?
Prehospital eFAST had high specificity for pneumothorax and hemoperitoneum, which is useful to prehospital providers and receiving EDs and could help determine hospital destination. Identification of pneumothorax on eFAST should make the prehospital provider more comfortable with intervention in the field when clinical status requires it. With low sensitivity, this test in the prehospital environment is only really helpful when it is positive. We don’t know much about the training and ultrasound proficiency of these prehospital ED physicians, so it is hard to know how to apply this to other ED physicians or paramedics. Prior prehospital literature does seems to reinforce that specificity is high, but sensitivity is too low to rely upon (1,2).
POCUS Pro-Tips and Clips
The eFAST exam is often considered an easier POCUS exam, but a basic level of expertise can significantly increase your accuracy. In the RUQ view, we often focus on Morrison’s pouch, but the inferior liver edge is actually the most sensitive area of the FAST exam for free fluid (3). When you’re over Morrison’s pouch, just slide inferiorly over the rib to bring the inferior liver edge into view (see below clip). For the LUQ, view the subdiaphragmatic space. This area above the spleen can often hide free fluid and will be missed if only viewing the splenorenal space. For the lung exam, you can use the low frequency probe in many cases. However, if you are having trouble determining if pleural slide is present, then switch to the high frequency linear probe. M-mode can be used as an adjunct but only improves accuracy for novice users (4).
Editor’s note: I appreciate Chris Thom for finding these clips of real patients. A seemingly negative FAST is actually positive with a simple movement of the probe. I’m learning so much from these POCUS posts! ~Clay Smith
Source
Diagnostic performance of prehospital EFAST in predicting CT scan injuries in severe trauma patients: a multicenter cohort study. Eur J Trauma Emerg Surg. 2025 Jan 9;51(1):4. doi: 10.1007/s00068-024-02693-7. PMID: 39789295
Additional References
- Lin KT, Lin ZY, Huang CC, et al. Prehospital ultrasound scanning for abdominal free fluid detection in trauma patients: a systematic review and meta-analysis. BMC Emerg Med. 2024;24(1):7. Published 2024 Jan 7.
- Partyka C, Coggins A, Bliss J, et al. A multicenter evaluation of the accuracy of prehospital eFAST by a physician-staffed helicopter emergency medical service. Emerg Radiol. 2022;29(2):299-306.
- Lobo V, Hunter-Behrend M, Cullnan E, et al. Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam. West J Emerg Med. 2017;18(2):270-280.
- Avila J, Smith B, Mead T, et al. Does the Addition of M-Mode to B-Mode Ultrasound Increase the Accuracy of Identification of Lung Sliding in Traumatic Pneumothoraces?. J Ultrasound Med. 2018;37(11):2681-2687.
