Focussed Assessment with Sonography for Trauma (FAST) scan

Dr Owen Kang and Dr Ian Bickle et al.

Focussed Assessment with Sonography for Trauma (FAST) scan is a point-of-care ultrasound examination performed at the time of presentation of a trauma patient. 

It is invariably performed by a clinician, who should be formally trained, and is considered as an 'extension' of the trauma clinical assessment process, to aid rapid decision making. Some studies have shown no significant difference in diagnostic accuracy between radiologists and non-radiologists 6

The chief aim, and many would say the sole aim, is to identify intra-abdominal free fluid (assumed to be haemoperitoneum in the context of trauma) allowing for an immediate transfer to theatre, CT or other.

Many papers have been published detailing the pros and cons of this investigation 1,2. It has a reported sensitivity of ~90% (range 75-100%) and a specificity of ~95% (range 88-100%) for detecting intraperitoneal fluid 4. Sensitivity for detecting solid organ injuries is much lower. 

It has replaced diagnostic peritoneal lavage as the preferred initial method for assessment of haemoperitoneum.

The sensitivity of FAST to assess for pneumothorax is low at ~40% but may still be better than a supine chest x-ray 7.

  • patient in supine position
  • 3.5-5.0 MHz convex transducer
  • five regions may be scanned 3:

An "extended FAST or eFAST" scan may be performed 7

  • fluid-filled bowel adjacent to the liver, spleen or kidneys
  • pre-existing ascites
  • epicardial fat pad may mimic haemopericardium
  • seminal vesicles mistaking for pevlic free fluid in the young male patient

Ultrasound was first utilised for the examination of trauma patients in the 1970s in Europe 8.

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Article information

rID: 26339
Sections: Physics, Approach
Tags: cases, trauma
Synonyms or Alternate Spellings:
  • Focussed assessment with sonography for trauma (FAST)
  • Focussed assessment with sonography for trauma scan
  • FAST scan
  • Extended FAST (EFAST) scan

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Cases and figures

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    Case 1: haemoperitoneum
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