Ultrasound - FAST
Trauma with risk of thoracic or abdominal injury
Suspected free abdominal fluid (ascites or ruptured ectopic pregnancy)
Contraindications (absolute in bold)
Airway management or resuscitation required
Indication for emergent laparotomy (e.g. shock with stab wound to abdomen)
Operative intervention (laparotomy or thoracotomy)
Consent is not required if the patient lacks capacity or is unable to consent
Brief verbal discussion is recommended if the situation allows
Less complex non-emergency procedure with low risk of complications
Failure to visualise structures (bowel gas, excess tissue, pain)
Failure of image interpretation (false negative or positive)
PPE: non-sterile gloves
Ultrasound machine and gel
Linear ultrasound probe (lung)
Curvilinear ultrasound probe (abdomen)
Ultrasound depth 5cm for anterior lung, 20cm for pericardium and abdomen
Lung: probe longitudinally at the midclavicular line, and using RUQ and LUQ views slid 1-2 rib spaces towards the head
RUQ: Probe vertical between ribs 8-11 at mid-axillary line (marker to patient’s head) with anticlockwise rotation
LUQ: Probe vertical between ribs 6-9 at left posterior axillary line (marker to patient’s head) with clockwise rotation
Suprapubic: probe 2cm superior to symphysis pubis in two planes (marker to patient’s right and head)
Subxiphoid: probe inferior to xiphoid directed towards patient’s left shoulder (marker to patient’s right)
Lung view: identify lung slide in more than three sites and look for haemothorax in axilla
RUQ view: identify anechoic fluid in Morrison’s pouch and around tip of liver
LUQ view: identify anechoic fluid in splenorenal recess and around tip of spleen
Suprapubic view (two planes): identify anechoic fluid in recto-vesicular space (males) or pouch of Douglas (females)
Subxiphoid view: identify anechoic strip of fluid in pericardial space
Clean ultrasound gel from patient
Initiate further management if required
Start scanning in the area most likely to yield results (RUQ in blunt trauma, lung and heart in chest trauma)
The liver is a useful acoustic window for both the subxiphoid and RUQ views
A 1cm stripe of anechoic stripe in Morrison’s pouch correlates to approximately 1 litre of fluid
FAST can be performed in less than three minutes and can reliably detect 200ml in the peritoneum. The utility of a FAST depends on the patient population. It almost 100% sensitive in hypotensive blunt trauma patients, meaning that a well-performed scan demonstrating no free fluid rules out the need for immediate emergency laparotomy.
Sensitivity falls in normotensive patients as some clinically significant injuries are not demonstrated by ultrasound (e.g. diaphragm tears, pancreatic lesions, bowel perforations), and other injuries may not have bled enough to be detectable (e.g. early mesenteric injury) on an initial scan. Serial ultrasound improves sensitivity and can detect haemorrhage accumulating over time.
If significant injury is suspected and the FAST examination is negative, the haemodynamically stable patient requires further imaging (usually CT).
This guideline has been reviewed and approved by the following expert groups:
Emergency Care Institute
Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.
Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges’ clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.
Dunn RJ, Borland M, O’Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.
Manoj P, et al (2019): In: UpToDate. Waltham (MA): UpToDate.: Emergency ultrasound in adults with abdominal and thoracic trauma
Emergency ultrasound imaging criteria compendium. Ann Emerg Med. 2016;68(1):e11-e48. doi:10.1016/j.annemergmed.2016.04.028
Dawson M, Mallin M. Introduction to bedside ultrasound: volume 1. New York NY: Apple Books; 2013.
Dawson M, Mallin M. Introduction to bedside ultrasound: volume 2. New York NY: Apple Books; 2013.