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A false-positive Focused Assessment with Sonography in Trauma (FAST) in a trauma patient

Lindsay Taylor1orcid, Fred Milgrim2orcid, Matthew Riscinti2orcid, Michael Gottlieb3orcid
Clinical and Experimental Emergency Medicine 2026;13(1):110-111.
Published online: February 9, 2026

1Department of Emergency Medicine, Virginia Commonwealth University Medical Center, Richmond, VA, USA

2Department of Emergency Medicine, Denver Health and Hospital Authority, University of Colorado, Denver, CO, USA

3Department of Emergency Medicine, Rush University Medical Center, Chicago, IL, USA

Correspondence to: Lindsay Taylor Department of Emergency Medicine, Virginia Commonwealth University Medical Center, 1250 E Marshall St, Richmond, VA 23219, USA Email: lataylor18@gmail.com
• Received: January 17, 2025   • Revised: March 18, 2025   • Accepted: March 19, 2025

© 2026 The Korean Society of Emergency Medicine

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/).

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What is already known
The focused assessment with sonography in trauma (FAST) exam is highly specific in detecting hemoperitoneum during early trauma evaluations and ruptured ectopic pregnancies, facilitating emergent surgery. Free fluid found in the hepatorenal recess is the most sensitive and earliest sign of hemoperitoneum.
What is new in the current study
Post-processing imaging enhancements are now standard on many modern ultrasound machines. These enhancements can cause a false-positive anechoic stripe between the liver and kidney on the FAST examination. This artifact can be reduced by decreasing speckle reduction, increasing the dynamic range, increasing dehaze, and decreasing the gray map. While these adjustments appear to decrease this artifact, there is a tradeoff in image quality. Without implementing these changes, awareness of this artifact is critical to avoid unnecessary computed tomography imaging or surgery.
A 26-year-old man presented to the emergency department after a dirt bike accident, reporting right rib pain and shortness of breath. He was tachycardic with otherwise normal vital signs. On examination, he had equal breath sounds and tenderness to the right chest wall. After the primary survey, a Focused Assessment with Sonography in Trauma (FAST) was performed with concern for free fluid in the right upper quadrant (Fig. 1A). He was deemed stable for computed tomography (CT) imaging to investigate for injuries (Fig. 1B). In this case, CT confirmed the ultrasound finding to be an artifact.
The FAST examination is an important tool in the assessment of trauma patients and is highly specific for hemoperitoneum [1,2]. In an unstable patient with abdominal trauma, a positive finding on the FAST will often guide the decision for operative management; stable patients will undergo CT imaging. A positive FAST examination is considered when there is an anechoic stripe present between the liver and kidney. A recent study described the “lipliner sign,” an artifact creating a false anechoic stripe between the liver and kidney on the FAST caused by post-processing imaging enhancements that are now standard on many modern ultrasound machines [3]. This artifact can be reduced by adjusting the machine settings: (1) decrease speckle reduction; (2) increase the dynamic range; (3) increase dehaze; or (4) decrease the gray map. While such adjustments can decrease the appearance of this artifact, there is a tradeoff in image quality. Without such changes, awareness of this artifact is critical to avoid unnecessary CT imaging or surgery.

Ethics statement

Informed consent was waived due to the retrospective nature of this study and no personal identification is on the images provided.

Author contributions

Conceptualization: all authors; Investigation: all authors; Writing–original draft: LT, MG; Writing–review & editing: all authors. All authors read and approved the final manuscript.

Conflicts of interest

Michael Gottlieb currently receives grant funding through the US Centers for Disease Control and Prevention, Bill and Melinda Gates Foundation, Biomedical Advanced Research and Development Authority, and the Society of Directors of Research in Medical Education. He is also an editorial board member of this journal, but was not involved in the peer reviewer selection, evaluation, or decision process of this article. The authors have no other conflicts of interest to declare.

Funding

The authors received no financial support for this study.

Data availability

Data sharing is not applicable as no new data were created or analyzed in this study.

Fig. 1.
Images of the patient. (A) An artifact creating a false anechoic stripe between the liver and kidney on the Focused Assessment with Sonography in Trauma (FAST) examination (arrow), caused by post-processing imaging enhancements. (B) Normal computed tomography image, demonstrating no intra-abdominal injury or free fluid.
ceem-25-011f1.jpg
  • 1. Patel NY, Riherd JM. Focused Assessment with Sonography in Trauma: methods, accuracy, and indications. Surg Clin North Am 2011;91:195-207.
  • 2. 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;18:270-80.
  • 3. Parker MA, Hicks BG, Kaili M, et al. The lipliner sign: potential cause of a false positive Focused Assessment with Sonography in Trauma (FAST) examination. J Emerg Med 2024;67:e553-9.

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A false-positive Focused Assessment with Sonography in Trauma (FAST) in a trauma patient
Clin Exp Emerg Med. 2026;13(1):110-111.   Published online February 9, 2026
DOI: https://doi.org/10.15441/ceem.25.011
Download Citation

Download a citation file in RIS format that can be imported by all major citation management software, including EndNote, ProCite, RefWorks, and Reference Manager.
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A false-positive Focused Assessment with Sonography in Trauma (FAST) in a trauma patient
Clin Exp Emerg Med. 2026;13(1):110-111.   Published online February 9, 2026
DOI: https://doi.org/10.15441/ceem.25.011
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A false-positive Focused Assessment with Sonography in Trauma (FAST) in a trauma patient
Image
Fig. 1. Images of the patient. (A) An artifact creating a false anechoic stripe between the liver and kidney on the Focused Assessment with Sonography in Trauma (FAST) examination (arrow), caused by post-processing imaging enhancements. (B) Normal computed tomography image, demonstrating no intra-abdominal injury or free fluid.

Fig. 1.

A false-positive Focused Assessment with Sonography in Trauma (FAST) in a trauma patient
CEEM : Clinical and Experimental Emergency Medicine

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