Related Experiment Video
Updated: Jun 19, 2026
Focused Assessment with Sonography for Trauma (FAST) Exam: Image Acquisition
Published on: September 22, 2023
The double-line sign: a false positive finding on the Focused Assessment with Sonography for Trauma (FAST)
Paul R Sierzenski1, Joel M Schofer, Michael J Bauman
1Section of Emergency Ultrasound, Department of Emergency Medicine, Christiana Care Health System, Newark, Delaware, USA.
Background:
Emergency physicians commonly perform Focused Assessment with Sonography for Trauma (FAST) examinations to evaluate for free intraperitoneal fluid. Many ultrasound findings can be misinterpreted as free fluid, resulting in false-positive FAST examinations.
Objectives:
To describe a previously unreported ultrasound finding that can be misinterpreted as free intraperitoneal fluid.
Case Report:
A 32-year-old man was stabbed in the left upper abdomen. A FAST examination was performed and a right perinephric fat pad was interpreted as showing free fluid in Morison's pouch. After transfer to a trauma center, a repeat FAST examination revealed no signs of intraperitoneal free fluid. Wound exploration showed no signs of penetration into the peritoneal cavity.
Conclusions:
When performing a FAST examination, a wedge-shaped hypoechoic area in Morison's pouch that is bounded on both sides by echogenic lines (the "FAST Double-Line Sign") is likely to represent perinephric fat and may result in a false-positive FAST examination.
More Related Videos
08:22The Application of Point-of-Care Ultrasonography (POCUS) in the Management of Acute Respiratory Distress Syndrome (ARDS) in the Intensive Care Unit
Published on: December 12, 2025
06:50Troubleshooting FoCUS Image Acquisition: Patient Positioning, Transducer Manipulation, and Image Optimization
Published on: March 3, 2023
Related Concept Videos
01:17Ultrasonography
During an ultrasonography procedure, a handheld device called a...
01:25Ultrasound II: Endoscopic Ultrasound and FibroScan
Endoscopic Ultrasound (EUS):