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Focused Assessment with Sonography in Trauma (FAST)

  • Author: Timothy Jang, MD; Chief Editor: Gowthaman Gunabushanam, MD, FRCR  more...
 
Updated: Sep 22, 2015
 

Overview

Background

Blunt abdominal trauma (BAT) is a common reason for presentation to the emergency department (ED). Unfortunately, patient history and physical examination often lack the necessary sensitivity and specificity to diagnose acute traumatic pathology accurately.

Diagnostic peritoneal lavage (DPL) was historically used to determine which patients needed exploratory laparotomy, but DPL is difficult to perform in pregnant patients, cannot be used for serial assessment, and is overly sensitive, which leads to a high negative laparotomy rate.[1]

Abdominal computed tomography (CT) has better specificity than DPL for intra-abdominal injury in BAT but can be difficult to perform in hemodynamically unstable patients, is expensive, requires removing patients from the clinical arena, and may be relatively contraindicated in pregnant patients.[2]

Focused assessment with sonography for trauma (FAST), on the other hand, is an important and valuable diagnostic alternative to DPL and CT that can often facilitate a timely diagnosis for patients with BAT.[3, 4, 5]

Guidelines for FAST examination have been published by the American Institute of Ultrasound in Medicine (AIUM) and the American College of Emergency Physicians (ACEP).[6]  The primary FAST examination classically includes the subxiphoid window of the heart to denote pericardial fluid. Indications for FAST include evaluation of the torso for free fluid suggesting injury to the peritoneal, pericardial, and pleural cavities, particularly in cases of trauma. FAST examination may be used to evaluate the lungs for pneumothorax.[6, 7, 8]

The benefits of the FAST examination include the following:

  • Decreases the time to diagnosis for acute abdominal injury in BAT
  • Helps accurately diagnose hemoperitoneum
  • Helps assess the degree of hemoperitoneum in BAT
  • Is noninvasive
  • Can be integrated into the primary or secondary survey and can be performed quickly, without removing patients from the clinical arena
  • Can be repeated for serial examinations
  • Is safe in pregnant patients and children, as it requires less radiation than CT
  • Leads to fewer DPLs; in the proper clinical setting, can lead to fewer CT scans (patients admitted to the trauma service and to receive serial abdominal examinations) [9]

An extended version of the standard FAST examination (E-FAST) has been established and offers additional information. In addition to imaging of the abdomen, the E-FAST examination includes views of bilateral hemithoraces to assess for hemothorax and views of bilateral upper anterior chest walls to assess for pneumothorax.[10, 11, 12, 13, 14, 15] For the remainder of this article, the FAST examination is referred to as the E-FAST examination, as appropriate.

For additional resources and education on trauma, see the Trauma Resource Center and Pediatric Abdominal Trauma, Penetrating Abdominal Trauma, Blunt Abdominal Trauma, and Abdominal Vascular Injuries.

Indications

There are several accepted indications for the FAST examination. They include the following:

Contraindications

When emergency treatments such as intravenous (IV) fluids or transfusion of blood are indicated, performance of a FAST examination should not delay the initiation of these treatments.

Although ongoing resuscitation and a patient in extremis are not contraindications, the FAST examination can be difficult to perform in such situations.

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Technique

Overview

Focused assessment with sonography for trauma (FAST) should include views of (1) the hepatorenal recess (Morison pouch), (2) the perisplenic view, (3) the subxiphoid pericardial window, and (4) the suprapubic window (Douglas pouch). If an extended FAST (E-FAST) examination is performed, views of (1) the bilateral hemithoraces and (2) the upper anterior chest wall should also be obtained. The videos below depict demonstrations of FAST and E-FAST, respectively.

Demonstration of focused assessment with sonography for trauma (FAST). Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) cardiac extension for E-FAST. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

Blood tends to pool in dependent areas. The hepatorenal recess (Morison pouch) is the most dependent space in the supramesocolic region. The suprapubic view allows assessment of fluid in the most dependent area in the inframesocolic region. In women, this space (the rectouterine space) is known as the pouch of Douglas.

To visualize the Morison pouch, the transducer-probe should be placed in the right upper quadrant or laterally along the thoracoabdominal junction (see the images below). This placement uses the liver as an acoustic window and avoids interference from air-filled bowel. The probe should be moved toward the inferior margin of the liver to obtain improved images of the right kidney.

Probe placement for right upper quadrant laterally Probe placement for right upper quadrant laterally.
Right upper quadrant view. Right upper quadrant view.
Focused assessment with sonography for trauma (FAST) that depicts fluid in the Morison pouch. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) depicting normal right upper quadrant findings. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

In cases of acute hemoperitoneum, blood appears as an anechoic stripe in the recess (see the image below).

Free fluid in Morison pouch. Free fluid in Morison pouch.

To obtain the perisplenic view, the transducer-probe should be placed over the left flank, lateral to the spleen along the posterior axillary line (see the images below). When placed in this position, the handle of the probe should nearly touch the gurney. This placement allows the spleen to be used as an acoustic window and avoids interference from air-filled bowel. The probe should then be moved superiorly (toward the thoracoabdominal junction) and inferiorly to assess for the presence of free fluid above the spleen and along the spleen tip.

Probe placement for left upper quadrant laterally. Probe placement for left upper quadrant laterally.
Left upper quadrant view. Left upper quadrant view.

Be sure to assess the hepatodiaphragmatic and splenodiaphragmatic spaces (see the images below); blood often accumulates in these areas. A common pitfall is to scan only through the hepatorenal and splenorenal spaces.

Blood in the splenodiaphragmatic recess. Blood in the splenodiaphragmatic recess.
Focused assessment with sonography for trauma (FAST) depicting fluid in the splenorenal space. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) depicting a normal splenorenal space. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

To obtain the suprapubic view, the probe should be placed just above the pubic symphysis and directed inferiorly into the pelvis (see the images below). This view is easier to obtain when the bladder is full and before the placement of a Foley catheter. Be sure to obtain both sagittal and transverse suprapubic views.

Suprapubic probe placement. Suprapubic probe placement.
Suprapubic view. Suprapubic view.
Focused assessment with sonography for trauma (FAST) depicting fluid in the pelvis, sagittal view. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

For the subxiphoid view, the transducer-probe should be placed in the subxiphoid area and directed into the chest toward the left shoulder so as to view the diaphragm and heart (see the images below). This view can be difficult to obtain if the patient is experiencing significant abdominal pain. It often requires pressing the probe into the abdomen and angling the probe so that it is nearly parallel to the skin. In such cases, it is helpful to place the palm over the top of the probe with the thumb on the indicator.

Subxiphoid probe placement. Subxiphoid probe placement.
Subxiphoid view that demonstrates traumatic tampon Subxiphoid view that demonstrates traumatic tamponade.

If the patient is experiencing significant abdominal pain or is obese, consider switching to a parasternal long-axis view. The subxiphoid long-axis view is another view that can be used to assess for pericardial effusions. This view also allows the examiner to assess the size and collapsibility of the inferior vena cava (IVC).

If an E-FAST examination is being performed to rule out pneumothorax, place a high-frequency linear probe (8-12 MHz) with the indicator toward the patient’s head in a long-axis orientation. Place the probe high on the patient’s chest, just below the clavicles in the midclavicular line. Look for the pleural line sitting at the back of the ribs. The presence of sliding between the visceral and parietal pleura indicates the absence of a pneumothorax in the area being scanned. The absence of sliding implies the presence of a pneumothorax. See the videos below.

Extended focused assessment with sonography for trauma (E-FAST) that shows no pneumothorax. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Extended focused assessment with sonography for trauma (E-FAST) that shows pneumothorax. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.

If an E-FAST examination is being performed to rule out hemothorax, the transducer probe should be placed laterally on the lower thorax just above the diaphragm. This can be visualized by sliding the probe superiorly from the standard right and left upper quadrant views. Blood appears as an anechoic stripe in the thorax.

Additional Considerations

If rib shadowing is an obstacle, rotate the transducer-probe 30° to fit between the ribs. Consider switching to a probe with a smaller footprint (eg, a phased array probe) if such a device is available.

If the desired recesses are difficult to visualize, ask the patient to take a slow, deep breath and, if possible, to hold it. This may move the recess into view.

Be sure to fully interrogate each region by scanning through it in its entirety. A single negative view in each region does not constitute a negative E-FAST examination.

Intraperitoneal free fluid may not be hemoperitoneum. Consider ascites, urine, peritoneal dialysate, and other sources of intraperitoneal fluid. Be aware of false positives from fatty tissue, and attempt to determine precisely where visualized fluid is located. In pregnant patients, the presence of free fluid after BAT may not be physiologic, especially if there is >2mm to 4mm, and the patient has no history of ovarian hyperstimulation syndrome.[16]

Hemoperitoneum may take time to accumulate. Maintain a low threshold for repeating the E-FAST examination, especially if the patient’s vital signs or examination change. Serial E-FAST examinations increase the sensitivity with which intraperitoneal free fluid secondary to blunt abdominal trauma can be detected.

The E-FAST examination is an excellent initial imaging modality for identifying the presence of hemothorax or pneumothorax in the setting of trauma. Although it is quite specific, it is not sensitive enough to rule out all significant pathology.

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Preparation

Anesthesia

Anesthesia is generally not necessary for sonographic evaluation. Analgesics may be required for pain control secondary to the particular trauma.

Equipment

Equipment requirements are modest. The examiner will need an ultrasound machine and ultrasound-conducting gel.

Positioning

Patients should be evaluated in the supine position but may be moved to the Trendelenburg or lateral decubitus position for improved visualization of particular views if there are no contraindications (eg, spinal precautions).

Male patients should have the entire abdomen exposed for the examination. Take care with female patients to minimize the exposure of sensitive areas.

Complication Prevention

Typically, no complications are associated with this procedure. No special efforts at complication prevention are required.

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Contributor Information and Disclosures
Author

Timothy Jang, MD Associate Professor of Clinical Medicine, University of California, Los Angeles, David Geffen School of Medicine; Director of Emergency Ultrasonography, Department of Emergency Medicine, Harbor-UCLA Medical Center

Timothy Jang, MD is a member of the following medical societies: American College of Emergency Physicians, American Institute of Ultrasound in Medicine, Christian Medical and Dental Associations, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Zahir Basrai, MD Fellow in Emergency Ultrasound, Division of Emergency Medicine, Harbor-UCLA Medical Center

Disclosure: Nothing to disclose.

Specialty Editor Board

Mary L Windle, PharmD Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Chief Editor

Gowthaman Gunabushanam, MD, FRCR Assistant Professor, Department of Diagnostic Radiology, Yale University School of Medicine

Gowthaman Gunabushanam, MD, FRCR is a member of the following medical societies: American Roentgen Ray Society, Connecticut State Medical Society

Disclosure: Nothing to disclose.

Additional Contributors

James Quan-Yu Hwang, MD RDMS, RDCS, FACEP, Staff Physician, Emergency Department, Kaiser Permanente

James Quan-Yu Hwang, MD is a member of the following medical societies: American Academy of Emergency Medicine, American College of Emergency Physicians, American Institute of Ultrasound in Medicine, Society for Academic Emergency Medicine

Disclosure: Received salary from 3rd Rock Ultrasound, LLC for speaking and teaching; Received consulting fee from Schlesinger Associates for consulting; Received consulting fee from Philips Ultrasound for consulting.

Acknowledgements

Christopher Angemi, DO Clinical Instructor, University of California, Los Angeles, David Geffen School of Medicine; Emergency Ultrasound Fellow, Department of Emergency Medicine, Harbor-UCLA Medical Center; Staff Physician, Department of Emergency Medicine, Bakersfield Memorial Hospital

Christopher Angemi, DO is a member of the following medical societies: American College of Emergency Physicians, American College of Osteopathic Emergency Physicians, American Osteopathic Association, and California Medical Association

Disclosure: Nothing to disclose.

Acknowledgments

Medscape Reference thanks Meghan Kelly Herbst, MD, Emergency Ultrasound Director, Department of Emergency Medicine, Hartford Hospital, for assistance with the video contribution to this article. Medscape Reference also thanks Yale School of Medicine, Emergency Medicine for assistance with the video contribution to this article.

References
  1. Jansen JO, Logie JR. Diagnostic peritoneal lavage - an obituary. Br J Surg. 2005 May. 92(5):517-8. [Medline].

  2. Griffin XL, Pullinger R. Are diagnostic peritoneal lavage or focused abdominal sonography for trauma safe screening investigations for hemodynamically stable patients after blunt abdominal trauma? A review of the literature. J Trauma. 2007 Mar. 62(3):779-84. [Medline].

  3. Bahner D, Blaivas M, Cohen HL, Fox JC, Hoffenberg S, Kendall J, et al. AIUM practice guideline for the performance of the focused assessment with sonography for trauma (FAST) examination. J Ultrasound Med. 2008 Feb. 27(2):313-8. [Medline].

  4. Korner M, Krotz MM, Degenhart C, Pfeifer KJ, Reiser MF, Linsenmaier U. Current Role of Emergency US in Patients with Major Trauma. Radiographics. 2008 Jan-Feb. 28(1):225-42. [Medline].

  5. Isenhour JL, Marx J. Advances in abdominal trauma. Emerg Med Clin North Am. 2007 Aug. 25(3):713-33, ix. [Medline].

  6. American Institute of Ultrasound in Medicine, American College of Emergency Physicians. AIUM practice guideline for the performance of the focused assessment with sonography for trauma (FAST) examination. J Ultrasound Med. 2014 Nov. 33 (11):2047-56. [Medline].

  7. Montoya J, Stawicki SP, Evans DC, Bahner DP, Sparks S, Sharpe RP, et al. From FAST to E-FAST: an overview of the evolution of ultrasound-based traumatic injury assessment. Eur J Trauma Emerg Surg. 2015 Mar 14. [Medline].

  8. Soult MC, Weireter LJ, Britt RC, Collins JN, Novosel TJ, Reed SF, et al. Can routine trauma bay chest x-ray be bypassed with an extended focused assessment with sonography for trauma examination?. Am Surg. 2015 Apr. 81 (4):336-40. [Medline].

  9. Helling TS, Wilson J, Augustosky K. The utility of focused abdominal ultrasound in blunt abdominal trauma: a reappraisal. Am J Surg. 2007 Dec. 194(6):728-32; discussion 732-3. [Medline].

  10. Kirkpatrick AW, Sirois M, Laupland KB, Liu D, Rowan K, Ball CG, et al. Hand-held thoracic sonography for detecting post-traumatic pneumothoraces: the Extended Focused Assessment with Sonography for Trauma (EFAST). J Trauma. 2004 Aug. 57(2):288-95. [Medline].

  11. Sheng AY, Dalziel P, Liteplo AS, Fagenholz P, Noble VE. Focused Assessment with Sonography in Trauma and Abdominal Computed Tomography Utilization in Adult Trauma Patients: Trends over the Last Decade. Emerg Med Int. 2013. 2013:678380. [Medline]. [Full Text].

  12. Fuchs PA, del Junco DJ, Fox EE, Holcomb JB, Rahbar MH, Wade CA, et al. Purposeful variable selection and stratification to impute missing Focused Assessment with Sonography for Trauma data in trauma research. J Trauma Acute Care Surg. 2013 Jul. 75(1 Suppl 1):S75-81. [Medline]. [Full Text].

  13. Barbosa RR, Rowell SE, Fox EE, Holcomb JB, Bulger EM, Phelan HA, et al. Increasing time to operation is associated with decreased survival in patients with a positive FAST examination requiring emergent laparotomy. J Trauma Acute Care Surg. 2013 Jul. 75(1 Suppl 1):S48-52. [Medline]. [Full Text].

  14. Bhoi S, Sinha TP, Ramchandani R, Kurrey L, Galwankar S. To determine the accuracy of focused assessment with sonography for trauma done by nonradiologists and its comparative analysis with radiologists in emergency department of a level 1 trauma center of India. J Emerg Trauma Shock. 2013 Jan. 6(1):42-6. [Medline]. [Full Text].

  15. Kärk Nielsen S, Ewertsen C, Svendsen LB, Hillingsø JG, Nielsen MB. Focused assessment with sonography for trauma in patients with confirmed liver lesions. Scand J Surg. 2012. 101(4):287-91. [Medline].

  16. Hussain ZJ, Figueroa R, Budorick NE. How much free fluid can a pregnant patient have? Assessment of pelvic free fluid in pregnant patients without antecedent trauma. J Trauma. 2011 Jun. 70(6):1420-3. [Medline].

 
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Probe placement for right upper quadrant laterally.
Right upper quadrant view.
Free fluid in Morison pouch.
Probe placement for left upper quadrant laterally.
Left upper quadrant view.
Blood in the splenodiaphragmatic recess.
Suprapubic probe placement.
Suprapubic view.
Subxiphoid probe placement.
Subxiphoid view that demonstrates traumatic tamponade.
Focused assessment with sonography for trauma (FAST) cardiac extension for E-FAST. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Demonstration of focused assessment with sonography for trauma (FAST). Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Extended focused assessment with sonography for trauma (E-FAST) that shows no pneumothorax. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Extended focused assessment with sonography for trauma (E-FAST) that shows pneumothorax. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) that depicts fluid in the Morison pouch. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) depicting fluid in the pelvis, sagittal view. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) depicting fluid in the splenorenal space. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) depicting normal right upper quadrant findings. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
Focused assessment with sonography for trauma (FAST) depicting a normal splenorenal space. Video courtesy of Meghan Kelly Herbst, MD. Also courtesy of Yale School of Medicine, Emergency Medicine.
 
 
 
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