Focused assessment with sonography in trauma (commonly

abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters or words taken from the full version of the word or phrase; for example, the word ''abbrevia ...

as FAST) is a rapid bedside

ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...

examination performed by surgeons, emergency physicians, and paramedics as a

screening test Screening, in medicine, is a strategy used to look for as-yet-unrecognised conditions or risk markers. This testing can be applied to individuals or to a whole population. The people tested may not exhibit any signs or symptoms of a disease, or t ...

for blood around the heart (

pericardial effusion A pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. The pericardium is a two-part membrane surrounding the heart: the outer fibrous connective membrane and an inner two-layered serous membrane. The two layers of t ...

) or abdominal organs (

hemoperitoneum Hemoperitoneum (also haemoperitoneum, sometimes also hematoperitoneum) is the presence of blood in the peritoneal cavity. The blood accumulates in the space between the inner lining of the abdominal wall and the internal abdominal organs. Hemope ...

) after

trauma Trauma most often refers to: * Major trauma, in physical medicine, severe physical injury caused by an external source * Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic i ...

. 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), peri

splenic The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

space,

pericardium The pericardium, also called pericardial sac, is a double-walled sac containing the heart and the roots of the great vessels. It has two layers, an outer layer made of strong connective tissue (fibrous pericardium), and an inner layer made o ...

, and the pelvis. 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 Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...

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 The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ...

by adding bilateral anterior thoracic

sonography Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, musc ...

to the FAST exam. This allows for the detection of a

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 i ...

with the absence of normal ‘lung-sliding’ and ‘comet-tail’ artifact (seen on the ultrasound screen). Compared with supine chest radiography, with CT or clinical course as the gold standard, bedside sonography has superior sensitivity (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, the detection of an otherwise ‘occult’ pneumothorax prior to CT scanning may hasten treatment and subsequently prevent development of a tension pneumothorax, a deadly complication if not treated immediately, and deterioration in the

radiology Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...

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

hemothorax A hemothorax (derived from hemo- lood+ thorax hest plural ''hemothoraces'') is an accumulation of blood within the pleural cavity. The symptoms of a hemothorax may include chest pain and difficulty breathing, while the clinical signs may incl ...

pleural effusion A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.6 millilitre per k ...

, 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

finding usually in an eFAST examination that can prove presence of a

. The sign is an imaging finding using a 3.5–7.5

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

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

empyema An empyema () is a collection or gathering of pus within a naturally existing anatomical cavity. For example, pleural empyema is empyema of the pleural cavity. It must be differentiated from an abscess, which is a collection of pus in a newly fo ...

, blood in pleural space (hemothorax).

Advantages

FAST is less invasive than

diagnostic peritoneal lavage Diagnostic peritoneal lavage (DPL) or diagnostic peritoneal aspiration (DPA) is a surgical diagnostic procedure to determine if there is free floating fluid (most often blood) in the abdominal cavity. Indications This procedure is performed when i ...

, involves no exposure to radiation and is cheaper compared to computed tomography, but achieves a similar accuracy. Numerous studies have shown FAST is useful in evaluating trauma patients. It also appears to make emergency department 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 The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of meso ...

. In the right upper quadrant this typically appears in Morison's Pouch (between the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

and

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

). 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 The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .

(perisplenic space). In the pelvis, blood generally pools behind the bladder (in the rectovesicular space). A positive result suggests hemoperitoneum; often CT scan will be performed if the patient is stable or a

laparotomy A laparotomy is a surgical procedure involving a surgical incision through the abdominal wall to gain access into the abdominal cavity. It is also known as a celiotomy. Origins and history The first successful laparotomy was performed without ane ...

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