FAST stands for Focused Assessment with Sonography for Trauma. This type of diagnostic imaging is used to look for free fluid in the chest or abdomen. It can be used for traumatic and non-traumatic medical situations. For example, if a patient is hit by a car, but also if we suspect heart failure or cancer. This type of imaging does not replace a full abdominal ultrasound, but it is extremely beneficial because it is non-invasive, low stress, it is rapid and repeatable, it guides therapy, and helps determine prognosis. It is especially useful in emergency situations and is a part of a gold standard triage of the emergency patient.