FAST Exam in Trauma Patients

                The Focused Assessment with Sonography for Trauma(FAST) is a useful tool in determining the need for emergent surgery in a trauma setting. The focus of the exam is to detect free fluid which will usually present as a hemopericardium, cardiac tamponade, or hemoperitoneum.  Indications for this exam include blunt trauma with suspected intraperitoneal injury, blunt trauma with shock out of proportion to injuries, penetrating thoracoabdominal trauma, and thoracoabdominal trauma in a pregnant patient. Solid organ injury detection is beyond the scope of FAST, however solid organ injury can be inferred by hemoperitoneum.

The various sensitivities and specificities for the given organ ailment utilizing the FAST exam is listed below:

Hemoperitoneum: Sn 82-98%, Sp 88-100%

Parenchymal injury: Sn 41-69%, Sp 88-100%

Hemopericardium: Sn 80-100%, Sp 96.3%

Predicting need for surgery for abdominal injury: Sn 81-90%, Sp 88-95%

 The FAST exam is performed in four anatomical regions. Of note, unclotted blood appears black on ultrasound and clotted blood appears as gray. The minimum amount of fluid detectable in a FAST scan is ~200-250cc.

Listed below are descriptions and images of both proper probe positioning and abnormal FAST exams for their given location.

1.  Perihepatic View/Morrison’s Pouch(RUQ)

Probe placement: perpendicular, mid-coronal plane, just superior to iliac crest

2. Perisplenic View (LUQ)

Probe placement: perpendicular, mid-coronal plane, just superior to iliac crest                             

 3. Subxiphoid View

Probe placement:  epigastrium, just inferior to xiphoid process, probe aimed at patient’s left shoulder

4.  Suprapubic View/Pouch of Douglas(Short Axis)

Probe placement: 2cm superior to symphysis pubis, midline of the abdomen

                        

References:

1. Bode PJ, et al. Abdominal ultrasound as a reliable indicator for conclusive laparotomy in blunt abdominal trauma. J Trauma 1993;34(1):27-31

2. Scalea TM, et al. Focused Assessment with Sonography for Trauma(FAST):results from an international consensus conference: J Trauma 1999;46(3):466-72

3. Ingeman, JE, et al. Emergency physicians use of ultrasonography in blunt abdominal trauma. Acad Emerg Med 1996;3(10):931-7

4. Rozycki GS, et al. A prospective study of surgeon-performed ultrasound as the primary adjuvant modality for injured patient assessment. J Trauma 1995;39(3):492-8

5. Images: http://www.fpnotebook.com/er/Rad/FstExm.htm

6. Images: http://www. pediatrics.uchicago.edu/chiefs/PER/documents/PedsFASTTupesis.ppt

This post provided by Dr. Bryan King.