Focused assessment with sonography in trauma (commonly

abbreviated An abbreviation () is a shortened form of a word or phrase, by any method including shortening, contraction, initialism (which includes acronym), or crasis. An abbreviation may be a shortened form of a word, usually ended with a trailing per ...

as FAST) is a rapid bedside

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

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

screening test In medicine, screening 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 without symptoms or signs of the disease being screened. Screening interv ...

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 tissue, connective membrane and an inner two-layered serous membrane ...

) 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. There is also the extended FAST (eFAST) which includes some additional ultrasound views to assess for pneumothorax. It may be useful prior to conducting more accurate tests such as CT in a stable trauma patient. 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 The pericardium (: pericardia), 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 inelastic connective tissue (fibrous pericardium), ...

, and the

pelvis The pelvis (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

. With this technique it is possible to identify the presence of moderate to large amounts 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, urethr ...

. FAST is poor at detecting smaller amounts of free fluid.

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 more accurate imaging or definitive care such as surgical intervention in the hemodynamically unstable patient.

Extended FAST

The eFAST allows for the examination of both

lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the backbone on either side of the heart. Their function in the respiratory syste ...

by adding bilateral anterior thoracic

sonography Medical ultrasound includes diagnostic techniques (mainly imaging) 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, muscles, joints ...

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

pneumothorax A pneumothorax is 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 dyspnea, shortness of breath. In a minority of cases, a one-way valve is ...

with the absence of normal ‘lung-sliding’ and ‘comet-tail’ artifact (seen on the ultrasound screen). Compared with supine chest radiography, bedside sonography has superior sensitivity (49–99% versus 27–75%), similar specificity (95–100%), and can be performed in under a minute, this making it well suited to settings without immediate access to more accurate investigations such as CT scanning. 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 Respiratory therapist, clinician familiarit ...

, 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 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 formed b ...

, a deadly complication if not treated immediately, and deterioration in the

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

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 inc ...

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 kilog ...

, 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), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...

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. The term is most commonly used to refer to pleural empyema, which is empyema of the pleural cavity. It is similar or the same in meaning as an a ...

, 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 (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 or ...

. However, compared with CT, FAST cannot accurately rule out life-threatening injuries and is of limited value in settings where CT is readily available. 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 (medicine), ...

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 to guide surgical interventions. 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 mesotheli ...

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

liver The liver is a major metabolic organ (anatomy), organ exclusively found in vertebrates, which performs many essential biological Function (biology), functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of var ...

and

kidney In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...

). 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 (, from Ancient Greek '' σπλήν'', splḗn) is an organ (biology), organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The spleen plays important roles in reg ...

(perisplenic space). In the

, blood generally pools behind the

bladder The bladder () is a hollow organ in humans and other vertebrates that stores urine from the kidneys. In placental mammals, urine enters the bladder via the ureters and exits via the urethra during urination. In humans, the bladder is a distens ...

(in the rectovesicular space). A positive result suggests hemoperitoneum; often

CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (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 or ...

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 ...

if unstable. In those with a negative FAST result, a search for extra-abdominal sources of bleeding may still need to be performed as FAST cannot reliably rule out bleeding or life threatening parenchymal injury. The value of FAST in situations where there is rapid access to CT or surgical intervention is limited, as a positive FAST requires either further investigation in the stable patient, or an operation in the unstable patient, and a negative FAST cannot rule out injury.

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 Diagnostic medical imaging Medical ultrasonography Traumatology