Focused Assessment with Sonography for Trauma (FAST) Exam: Image Acquisition

Over the past twenty years, the Focused Assessment with Sonography for Trauma (FAST) exam has transformed the care of patients presenting with a combination of trauma (blunt or penetrating) and hypotension. In these hemodynamically unstable trauma patients, the FAST exam permits rapid and noninvasive screening for free pericardial or peritoneal fluid, the latter of which implicates intra-abdominal injury as a likely contributor to the hypotension and justifies emergent abdominal surgical exploration. Further, the abdominal portion of the FAST exam can also be used outside of the trauma setting to screen for free peritoneal fluid in patients who become hemodynamically unstable in any context, including after procedures that may inadvertently injure abdominal organs. These "non-trauma" situations of hemodynamic instability are often triaged by providers from specialties other than emergency medicine or trauma surgery who are not familiar with the FAST exam. Therefore, there is a need to promulgate knowledge about the FAST exam to all clinicians caring for critically ill patients. Toward this end, this article describes FAST exam image acquisition: patient positioning, transducer selection, image optimization, and exam limitations. Since the free fluid is likely to be found in specific anatomic locations that are unique for each canonical FAST exam view, this work centers on the unique image acquisition considerations for each window: subcostal, right upper quadrant, left upper quadrant, and pelvis.