Focused assessment with sonography in trauma (commonly abbreviated as FAST) is a rapid bedside ultrasound examination performed by surgeons, emergency physicians, and paramedics as a screening test for blood around the heart ( pericardial effusion) or abdominal organs ( hemoperitoneum) after trauma. There is also the extended FAST (eFAST) which includes some additional ultrasound views to assess for pneumothorax. The four classic areas that are examined for free fluid are the perihepatic space (including Morison's pouch or the

hepatorenal recess The hepatorenal recess (subhepatic recess, pouch of Morison or Morison's pouch) is the subhepatic space that separates the liver from the right kidney. As a potential space, the recess is not normally filled with fluid. However, fluid can collect ...

), peri splenic space, pericardium, and the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

. With this technique it is possible to identify the presence of intraperitoneal or pericardial free fluid. In the context of traumatic injury, this fluid will usually be due to bleeding.

Indications

Reasons a FAST or eFAST would be performed would be: #Blunt abdominal trauma #Penetrating abdominal trauma #Blunt thoracic trauma #Penetrating thoracic trauma #Undifferentiated shock (low blood pressure)

Contraindications

Since the FAST/eFAST is performed with ultrasound, there is very little risk to the patient as ultrasounds only emit sound waves and record the echo to create a picture. The most common contraindication would be delay of definitive care such as surgical intervention in the setting of obvious trauma or resuscitative efforts in an extreme scenario.

Extended FAST

The eFAST allows for the examination of both lungs by adding bilateral anterior thoracic sonography to the FAST exam. This allows for the detection of a pneumothorax with the absence of normal ‘lung-sliding’ and ‘comet-tail’ artifact (seen on the ultrasound screen). Compared with supine

chest radiography A chest radiograph, called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in med ...

, with CT or clinical course as the gold standard, bedside sonography has superior

sensitivity Sensitivity may refer to: Science and technology Natural sciences * Sensitivity (physiology), the ability of an organism or organ to respond to external stimuli ** Sensory processing sensitivity in humans * Sensitivity and specificity, statisti ...

(49–99% versus 27–75%), similar specificity (95–100%), and can be performed in under a minute. Several recent prospective studies have validated its use in the setting of trauma resuscitation, and have also shown that ultrasound can provide an accurate estimation of pneumothorax size. Although radiography or CT scanning is generally feasible, immediate bedside detection of a pneumothorax confirms what are often ambiguous physical findings in unstable patients, and guides immediate chest decompression. In addition, in the patient undergoing

positive-pressure ventilation Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation. The mode refers to the method of inspiratory support. In general, mode selection is based on clinician familiarity and institutional pre ...

, the detection of an otherwise ‘occult’ pneumothorax prior to CT scanning may hasten treatment and subsequently prevent development of a

tension pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve is ...

, a deadly complication if not treated immediately, and deterioration in the radiology suite (in the CT scanner).

Components of the Examination

There are five components to the eFAST exam: # Right Upper Quadrant of the abdomen (Perihepatic view). Right upper quadrant is examined by working your probe down the midaxillary line starting at the right 8th rib to the 11th rib. This examines for free fluid around the kidney and liver. # Left Upper Quadrant of the abdomen (Perisplenic view). Left upper quadrant is examined by working your probe down the midaxillary line starting at the left 8th rib to the 11th rib. This examines for free fluid around the kidney and spleen. # Pelvic views (Long and transverse axis). The suprapubic view helps assess for free fluid in the pelvic cavity. # Cardiac view. The pericardial component is assessed using the subxiphoid view. # Lung views (Right and Left, Long axis). These final views help determine if a pneumothorax is present.

Findings

eFAST (extended focused assessment with sonography for trauma) allows an emergency physician or a surgeon the ability to determine whether a patient has pneumothorax, hemothorax, pleural effusion, mass/tumor, or a lodged foreign body. The exam allows for visualization of the echogenic tissue, ribs, and lung tissue. Few radiographic signs are important in any trauma and they include the ''stratosphere sign'', the ''sliding or seashore sign'', and the ''sinusoid sign.'' ''Stratosphere sign'' is a clinical medical ultrasound finding usually in an eFAST examination that can prove presence of a pneumothorax. The sign is an imaging finding using a 3.5–7.5 MHz ultrasound probe in the fourth and fifth intercostal spaces in the anterior clavicular line using the M-Mode of the machine. This finding is seen in the M-mode tracing as pleura and lung being indistinguishable as linear hyperechogenic lines and is fairly reliable for diagnosis of a pneumothorax. Even though the stratospheric sign can be an indication of pneumothorax its absence is not at all reliable to rule out pneumothorax as definitive diagnosis usually requires X-ray or CT of thorax. ''Seashore sign'' is another eFAST finding usually in the lungs in the M-mode that depicts the glandular echogenicity of the lung abutted by the linear appearance of the visceral pleura. This sign is a normal finding. In absence of a seashore sign or presence of a stratosphere sign, pneumothorax is likely. B-lines or "comet trails" are echogenic bright linear reflections beneath the pleura that are usually lost with any air between the probe and the lung tissue and therefore whose presence with seashore sign indicates absence of a pneumothorax. ''Sinusoid sign'' is another M-mode finding indicating presence of pleural effusion. Due to the cyclical movement of the lung in inspiration and expiration, the motion-time tracing (M-mode) ultrasound shows a sinusoid appearance between the fluid and the line tissue. This finding indicates a possible pleural effusion, empyema, blood in pleural space (hemothorax).

Advantages

FAST is less invasive than diagnostic peritoneal lavage, involves no exposure to radiation and is cheaper compared to

computed tomography A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

, but achieves a similar accuracy. Numerous studies have shown FAST is useful in evaluating trauma patients. It also appears to make

emergency department An emergency department (ED), also known as an accident and emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of pati ...

care faster and better. File:UOTW 18 - Ultrasound of the Week 1.webm, Negative FAST but full stomach File:UOTW 18 - Ultrasound of the Week 2.webm, Negative FAST but full stomach File:UOTW 18 - Ultrasound of the Week 3.webm, Negative FAST but full stomach

Interpretation

FAST is most useful in trauma patients who are hemodynamically unstable. A positive FAST result is defined as the appearance of a dark ("anechoic") strip in the dependent areas of the peritoneum. In the right upper quadrant this typically appears in

Morison's Pouch The hepatorenal recess (subhepatic recess, pouch of Morison or Morison's pouch) is the subhepatic space that separates the liver from the right kidney. As a potential space, the recess is not normally filled with fluid. However, fluid can collect ...

(between the liver and kidney). This location is most useful as it is the place where fluid will collect with a supine patient. In the left upper quadrant, blood may collect anywhere around the spleen (perisplenic space). In the

, blood generally pools behind the bladder (in the rectovesicular space). A positive result suggests hemoperitoneum; often

CT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

will be performed if the patient is stable or a laparotomy if unstable. In those with a negative FAST result, a search for extra-abdominal sources of bleeding may still need to be performed.

References

;Further reading *

External links

Focus On: EFAST - Extended Focused Assessment With Sonography for Trauma
American College of Emergency Physicians (ACEP)

FAST exam tutorial

from Trauma.org, includes tutorial videos.
Trauma FAST Exam - LUQ Exam

Lung ultrasound
ICU Sonography
''FOB Doc''
Capt Ray Wiss, MD. By a pioneering teacher of FAST to ER and first responders, civilian and military. {{Trauma, state=autocollapse Diagnostic emergency medicine Medical ultrasonography Traumatology