The eFAST exam is done in real time B-mode imaging. With the patient in the supine position at [16] the level of the examiner’s waist, scan from the patient’s right. This will allow the provider’s right hand to manipulate the probe while the left adjusts gain and depth to optimize image acquisition. For transverse images, position the probe with the indicator toward the patient’s right. For sagittal views, the indicator points in the direction of the patient’s head.

RUQ: Place the curvilinear probe along the posterior to the mid-axillary line between the 8 and 11 rib spaces to establish a coronal view of the interface between the liver and right kidney, known as Morrison’s pouch. Sweep anteriorly and posteriorly to evaluate the entirety of this space. Slide the probe caudally to evaluate the liver tip and the right paracolic gutter. Move the probe cephalad to visualize the diaphragm and inferior hemithorax, utilizing the liver as an acoustic window. Rib shadowing may obscure imaging. Mitigate this complication by rotating the probe to an oblique position. Additionally, if the patient is alert and cooperative, have the patient inhale deeply and hold. This will displace intraabdominal contents inferiorly below the ribs, allowing for a more complete visualization of the dependent recesses.

Pericardium: Position the probe just below the xiphoid process in the transverse orientation. Increase the depth in order to view the entire pericardium. Use the liver as an acoustic window to enhance your image. Typically, a shallow probe angle of less than 15 degrees is necessary to see the entire cardiac silhouette. An overhand grip is ideal to achieve this angle of approach. Patient body habitus can limit the subxiphoid window. Have the patient inhale deeply or try parasternal windows to assess for pathologic pericardial fluid.

LUQ: Typically, the left upper quadrant dependent recesses are more posterior and cephalad since the spleen is generally smaller than the liver. Begin with the transducer along posterior axillary line between the 6 and 9 rib spaces in the sagittal orientation. Fan anteriorly and posteriorly to survey the splenorenal and perisplenic spaces. Move cephalad to view the subphrenic space and the left inferior hemithorax. Slide caudally to image the left paracolic gutter.

Suprapubic: Locate the pubic symphysis and place the transversely oriented probe immediately cephalad to it. A full bladder is preferable, however if the bladder is decompressed aim the probe caudally. Increase the depth to visualize posterior to the bladder where free fluid collects. Sweep caudally and cephalad to obtain complete views of the rectovesical space in men and the rectouterine and vesico-uterine pouches in women. These pouches are the most dependent recesses of the intraperitoneal cavity.  In order to achieve greater sensitivity, rotate the probe 90 degrees clockwise into the sagittal orientation to best assess the pouch of Douglas and vesico-uterine pouch in women.

Anterior Thoracic: With the patient supine, position the probe in the longitudinal orientation along the midclavicular line at the third to fourth intercostal space (with an upright patient the first or second intercostal space is more sensitive). This is the most anterior portion of the thoracic cavity where free air accumulates as a pneumothorax. Normally, the visceral and parietal pleurae move against one another, creating a sliding artifact known as the “ants marching” sign. Absence of this movement is indicative of disruption between the serosal membranes by the presence of air. The presence of comet tail artifacts and B-lines indicate the absence of a pneumothorax, though. [17]

If B-mode imaging is equivocal for lung sliding, change to M-mode. The resulting grayscale heterogenous image will have a distinct interface at the level of the pleurae. Normal lung sliding creates a grainy artifact below the pleural line known as the “sandy beach” or “seashore” sign. In the setting of a pneumothorax, the resulting homogenous image lacks this grainy artifact, which is known as the “barcode” or “stratosphere” sign. Likewise, the presence of a lung-point sign is virtually pathognomonic of a pneumothorax. Numerous studies have demonstrated that ultrasound is far more sensitive than plain radiography and physical exam for diagnosing pneumothoraces with specificities of 99% [18] [16]. 

There are no known complications from the eFAST exam. However, ultrasound has several limitations. It is only 85% sensitive requiring the presence of more than 150 cc to 200 cc of intra-peritoneal fluid to detect [19]. Serial FAST exams can help prevent false-negative studies [7]. Other false negatives include patients with delayed presentations whose hemorrhage has clotted causing a mixed echogenicity rather than the anechoic or black appearance of fresh blood or fluid. False positives include ascites, peritoneal dialysate, ruptured ovarian cysts, and ruptured ectopic pregnancies. Additionally, ultrasound cannot distinguish between blood and urine in severe pelvic trauma and cannot evaluate retroperitoneal hemorrhages.

Most importantly, the point of care ultrasound image acquisition and interpretation is limited by the provider’s experience; the patient’s body habitus; and the presence of bowel gas, pneumoperitoneum, or pneumomediastinum. Serial eFAST exams and advanced imaging are warranted in these situations based on the patient’s hemodynamic status.

Ultrasound has revolutionized the care of traumatic injuries. Numerous studies, albeit mostly observational, have demonstrated that the eFAST protocol is a clinically significant adjunct in the evaluation and treatment of trauma patients. The EAST (Eastern Association for the Surgery of Trauma) guidelines, Western Trauma Association, and ATLS recommend the eFAST as the standard of care in trauma resuscitation protocols. The eFAST has been shown to decrease time to operative intervention; patient length of stay; cost; and the rates of complications, CTs, and DPLs performed [1]. As with any imaging modality though, recognize and understand its limitations.

The management of trauma patients is usually with an interprofessional team including trauma nurses. While FAST is useful in trauma patients, it has limitations. Clinicians should be aware that the point of care ultrasound image acquisition and interpretation is limited by the provider’s experience; the patient’s body habitus; and the presence of bowel gas, pneumoperitoneum, or pneumomediastinum. Serial eFAST exams and advanced imaging are warranted in these situations based on the patient’s hemodynamic status. A radiologist should be consulted if one is not able to interpret the images; unfortunately this may not always be possible in the middle of the night.[20][21]