Table of Contents
- Case Overview
- Statement of Consent
This video-article covers pertinent information related to the focused assessment with sonography for trauma exam, which evaluates the pericardial, hepatorenal, splenorenal, and suprapubic regions for free fluid in a trauma patient. It also covers additional information regarding the extended focused assessment with sonography for trauma (EFAST) exam, which includes an additional evaluation of the pleural spaces for a pneumothorax.
The focused assessment with sonography for trauma (FAST) exam has been used since the 1970s but became prevalent in the United States in the 1990s after a landmark paper by Dr. Grace Rozycki.1 Performing an extended focused assessment with sonography for trauma (EFAST) exam has become standard practice in the initial evaluation of a trauma patient.2 Many studies have proven that an EFAST exam is a helpful tool for elucidating the presence of free intraperitoneal fluid,3,4 a pericardial effusion, and a pneumothorax.5,6 The exam has been part of the Advanced Trauma Life Support (ATLS) algorithmic approach to the treatment of trauma patients set forth by the American College of Surgeons since the late 1990s (ACS).7
To begin, all exams require a coupling gel to be applied between the probe and the patient in order to obtain the images. This is because ultrasound waves cannot penetrate air.8 Free fluid is usually completely anechoic (black in color) on imaging and has sharp and acute angular edges.8 For probe selection, either the phased array or the curvilinear probe is used for all views of the EFAST exam.2,9 These probes are low frequency/long-wavelength probes and can penetrate deep into the body.8 Regardless of which probe is chosen, it is usually best to complete the entire exam with this probe in order to save time. However, the pleural exam will require reducing the imaging depth dramatically on both probes, which in turn may lead to poorer resolution and increased difficulty identifying a pneumothorax. In this case, it may be necessary to switch to the high frequency/short wavelength linear probe in order to detect a pneumothorax.2,10,11
The subxiphoid view evaluates for free fluid in the pericardial space. Place the probe indicator towards the patient’s right side.10 Find the xiphoid process and place the probe below it at the right subcostal margin. Angle the ultrasound beams superior and towards the patient’s left shoulder directly at the heart.9,10 To optimize the picture, adjust the depth and gain.12 The left of the screen correlates with the patient’s right side, and the right side of the screen correlates with the patient’s left side. The top of the screen correlates with tissues that are directly inferior to the xiphoid process/right costal margin (i.e. liver), and the bottom of the screen correlates with those tissues that are cephalad. Look at the intersection between the liver and the right ventricle to determine if the free fluid is present.9 If there is trouble viewing the heart, attempt to increase your use of the liver to visualize the heart by sliding the probe towards the patient's right inferior costal margin, while still maintaining the same orientation noted above.2 Make sure the angle between the bottom of the probe and the anterior abdominal wall of the patient is not too acute. The probe in most cases should be completely flattened and resting on the anterior abdominal wall to be able to view the heart clearly.9 If the heart cannot be visualized via the subxiphoid view in a timely manner (30 seconds to one minute) move on to the parasternal long cardiac view.2,10
Find the 2nd/3rd intercostal space parasternally on the patient’s left side. Place the indicator towards the patient’s right shoulder and place the probe perpendicularly on the chest wall.10 Come down one interspace at a time until the cardiac activity is visualized.10 Once visualized, adjust the depth to have the descending aorta at the bottom of the image. In this view, pericardial fluid is located at the bottom of the image, which correlates to the most gravitationally dependent area of the pericardium. Remember that pericardial fluid may be present but not be causing pericardial tamponade. It is important to assess for right ventricular collapse during diastole, which is sonographic evidence of cardiac tamponade, a type of obstructive shock.2,9,13 The pericardial view on the FAST exam can detect as little as 20 cc of pericardial fluid.14 Keep in mind that the rate of accumulation, not the amount of fluid, is the determining factor for a patient going into obstructive shock.
Align the probe indicator towards the patient’s head. Find the anterior axillary, midaxillary, and posterior axillary lines. Start the exam at the midaxillary line at the level of the xiphoid process, approximately between the 8th and 11th rib spaces.2,9 Aim the probe posteriorly at the spine. Look for the interface between the kidney and liver. This is a potential space, known as Morrison’s pouch. Ultrasound may be able to detect as little as 200 ml of fluid in this space.15 If there is fluid present in the peritoneum, the liver lifts off the kidney, and anechoic (black) fluid appears at this interface.10 The kidney, liver, diaphragm, and spine are visualized in this hepatorenal view. To optimize the image, set depth and gain so that the spine is at the bottom of the image. Look also at the hemithorax for free fluid.10 The diaphragm will move inferiorly with inhalation, and because ultrasound cannot penetrate air, fewer of the vertebrae of the spine will be visible with deep inspiration. A mirror image artifact is present when it appears as though the liver is visible cephalad and caudal to the diaphragm. A mirror image artifact is normal and rules out fluid in the hemithorax.9 Lack of mirror image artifact in the lung represents pathology such as hemothorax or pleural effusion.9 A black anechoic area of fluid will show up behind the diaphragm.15 This fluid will allow visualization of the vertebrae superior to the diaphragm at the bottom of the image. This is known as a positive “spine sign”.15 In a trauma patient, this represents a hemothorax.2
One pitfall is angling the transducer too horizontally instead of aiming the ultrasound beams posteriorly, down towards the spine. The second pitfall is placing the transducer on the anterior axillary line instead of the posterior axillary line. Placing the probe on the anterior axillary line will limit the ability to visualize the intraperitoneal structures as the ultrasound beams may be scattered by bowel gas. The third pitfall is not scanning through the inferior tip of the liver. This is the first place where fluid collects, and thus the most sensitive area of the hepatorenal view to detect free fluid.2,10,16 The last pitfall is mistaking edge artifact for free fluid. There can often be a minimal black shadow that appears between the kidney and liver edges. Free fluid has to collect in the most gravitationally dependent area, which is the above mentioned inferior tip of the liver.2,10,16 One pearl is to rock your probe inferiorly to increase visualization of the inferior liver tip. After you have visualized the tip you should fan through it in order to evaluate for any traces of free fluid. A second pearl is to angle the probe indicator towards the bed and angle your probe between the patient’s ribs in order to avoid any shadows they may cast onto the screen.2
Align the probe indicator towards the patient’s head. Find the left anterior axillary, midaxillary, and posterior axillary line. Start the exam at the posterior axillary line at or slightly above the level of the xiphoid process 2,10 approximately between the 7th and 10th rib. Place your thumb on the underside of the probe, index finger on top of the probe. Reaching across the patient, firmly place the knuckles of the hand holding the probe onto the stretcher.10 This will angle the probe slightly anteriorly towards the patient's spine. Obtain a view of the left kidney, the spleen, and the left hemidiaphragm. You are looking for black, anechoic fluid between the spleen and the kidney.9,10
For image optimization, adjust depth and gain.12 Try to visualize the spleen, left kidney, vertebrae, and diaphragm in one view. It is important to remember that the spleen and left kidney are anchored by the splenorenal ligament. This means that if fluid accumulates between the spleen and left kidney, it will not separate the left kidney completely from the spleen the way the right kidney separates from the liver.10 Fluid will typically accumulate around the inferior border of the spleen and it will track superiorly towards the diaphragm.
One pitfall is the failure to place the transducer on the posterior axillary line; most novice users place the probe on the midaxillary line. The left kidney is more superior and posterior in its location when compared with the right.2,10 Another pitfall is failing to realize that the spleen/left kidney is anchored, thus obtaining an image of the interface between the two organs but not the inferior tip of the spleen.
Pearls for left upper quadrant imaging emphasize probe positioning. Once the spleen, left kidney, and diaphragm are in view, slide or rock the probe superiorly and inferiorly to optimize the view. It is important to find the above mentioned inferior tip of the spleen. Fan through the inferior spleen tip in order to find any traces of free fluid.10 Additionally, don’t forget to check for the presence of a spine sign on the patient’s left.15,17
Place the probe in the suprapubic region, just superior to the pubic symphysis, with the indicator towards the patient’s right side.2 In this transverse/axial plane with the probe perpendicular to the skin, fan the probe cephalad and caudal through the patient's pelvis).10 In a male patient, free fluid should be found behind the bladder. In female patients, free fluid is found behind the uterus anterior to the rectum within the rectouterine pouch (i.e. Pouch of Douglas).2,10,18 Remember to fan the probe superiorly and inferiorly to scan the entire pelvis.9,10 Once complete, rotate the probe 90 degrees with the indicator towards the patient’s head to obtain a sagittal/longitudinal plane.2,17 Again fan the probe, this time from right to left to scan through the entire pelvis.10 You are looking for black, anechoic fluid, which should have sharp/acute angles. For image optimization, adjust the depth so you can see the bladder, prostate (male), uterus (female), and space just deep to these organs.
One common pitfall is placing the probe infraumbilical instead of suprapubic. If the probe is too high, bowel gas interferes with imaging.2 Another pitfall is failing to realize that pelvic free fluid accumulates in different places for men and women as mentioned above. Failing to recall that free fluid is anechoic with acute angles15 and that it allows the sonographer to identify additional structures otherwise hidden by bowel gas is an additional pitfall. It is easier to visualize an image when the ultrasound waves are traveling through fluid; it is impossible to do so when they are going through gas/air.2 One pearl is to compensate for the posterior acoustic enhancement (PAE) artifact caused by the bladder with time gain compensation. PAE artificially increases the gain of any tissues that lie just beyond a fluid-filled structure (e.g., bladder). This artificial increase could cause the sonographer to miss free anechoic black fluid. Turning down the gain beyond the bladder (shifting grayscale towards the anechoic end of the spectrum) allows the sonographer to better visualize anechoic free fluid in the pelvis.
This view can be obtained using either the linear (high frequency), phased array (low frequency), or curvilinear (low frequency) probes.11 If using the phased array or curvilinear probes, be sure to decrease the depth to better visualize the pleural line. Place the probe between 2nd and 3rd intercostal spaces along the midclavicular line with the indicator towards the patient’s head.2,9,10,11 Identify two ribs, their accompanying shadows, and the pleural line between them on the screen. The pleural line represents the opposed visceral and parietal pleurae.8 Depending on the presence or absence of various sonographic artifacts (e.g., comet-tail artifacts, lung sliding, A-lines, B-lines, lung point sign), the examiner is able to diagnose a variety of lung pathologies (e.g., pneumothorax).9,11 When a patient with healthy lungs takes a breath, horizontal “sliding” along this line represents a normal movement.8,15 Often “comet tail artifacts” are also seen.11 If sliding is not visualized, a pneumothorax may be present.8,10 M mode, which represents motion over time, is a useful adjunct for visualizing lung sliding. It samples motion along one area (designated line) on the screen. The motion detected is represented on the vertical (y) axis across time, the horizontal (x) axis, on the M mode graph. In a patient with normal lung sliding on M mode, everything above the pleural line appears linear (representing absence of movement). Everything below the pleural line is grainy. This is called the “seashore sign”.9,10 If a patient has a pneumothorax, you would expect to see only horizontal lines, also known as the “barcode” or “stratosphere” sign, due to the absence of pleural movement.2,10,11 A highly specific ultrasound sign for a pneumothorax is the “lung point”, which visualizes the point where the visceral pleura (lung) begins to separate from the parietal pleura (chest wall) at the edge of a pneumothorax.2,11,19 When the examiner places the probe at the “lung point” while using M mode, you would see alternating “seashore” and “barcode” signs as the patient inhales and exhales.8 The position of the lung point depends on the size of the pneumothorax.11,19
For image optimization, adjust the depth to adequately see the pleural line. This is especially important for the phased array and curvilinear probes. Failing to do so is a common pitfall. A second pitfall is failing to use M mode to help identify the presence of either a seashore sign or a lung point.2 A third pitfall is failing to realize that absence of lung sliding or “barcode sign” with M mode when visualizing left hemothorax in an intubated patient may represent a right mainstem intubation instead of a pneumothorax.9,11,20 Try to identify a “lung point” on the left side if there is a concern for a possible pneumothorax on this side. One pearl is to scan superiorly and inferiorly between the 2nd and 4th intercostal spaces to look for a large pneumothorax.
The indications for this exam, based on the American College of Emergency Physicians' policy statement, are to rapidly evaluate the torso for evidence of traumatic free intraperitoneal fluid or pathologic air suggestive of injury in the following cavities: peritoneal, pericardial, and pleural.15,21 There are no absolute contraindications to the FAST/EFAST examination.2 However, certain instances may preclude the exam, such as severely damaged tissues/open wounds or the need for immediate operative intervention.21 Yet, even when a patient is going to the OR for emergent laparotomy, it is still acceptable to take time to evaluate for other life-threatening emergencies including tension pneumothorax or pericardial tamponade that could be treated prior to going to the operating room.
The sensitivity and specificity of the FAST and EFAST exams range broadly. For instance, one meta-analysis systematically reviewed studies on penetrating and blunt trauma and found the pooled sensitivities and specificities of the EFAST exam to be 69% and 99% for detecting pneumothorax, 91% and 94% for pericardial effusion, and 74% and 98% for intra-abdominal free fluid, respectively.5 These numbers are influenced by many factors including blunt vs penetrating abdominal trauma,9 hemodynamic status, and the area of the body being examined. Broadly speaking, the exam is more specific than it is sensitive.5 Thus, a negative FAST exam does not rule out traumatic injury.10 For example, up to 29% of patients with a negative FAST exam still have intra-abdominal injuries.22,23 It is more sensitive in blunt abdominal trauma than penetrating trauma. For blunt abdominal trauma, sensitivities generally range from 73–99% for detecting free intraperitoneal fluid.3,8,24 The specificity of the FAST exam for both blunt and penetrating abdominal trauma is 94–100%.8,25 It is more sensitive than specific when evaluating pathology in the pleural and pericardial spaces compared with the peritoneal space.26,27 EFAST is also more sensitive for detecting pneumothoraces compared with chest radiographs.2,8,11,15,28,29,30 Supine chest radiographs performed during ATLS have a range of sensitivities between 28–75% for detecting traumatic pneumothorax, compared with the EFAST exam, which has a higher sensitivity of 86–97%.31 One study found the sensitivity and specificity for detecting hemothorax in blunt thoracic trauma patients to be 92% and 100%, respectively.32 To visualize hemothoraces, supine or upright chest X-rays require up to 50–175 ml of fluid, compared with the EFAST exam, which can detect as little as 20 ml of fluid in the pleural space.33 A highly specific ultrasound finding for a pneumothorax is the lung point, which boasts a sensitivity of 59–75% and specificity of 99–100%.7,18 Ultrasound can also detect as little as 20 ml of pericardial fluid in a penetrating chest trauma patient.14 The sensitivity and specificity also vary with the skill level of the operator and the patient’s body habitus.2,15, 26, 34
A phased array (or cardiac) probe or a curvilinear (or abdominal) probe
Nothing to disclose.
The patient referred to in this video article has given their informed consent to be filmed and is aware that information and images will be published online.
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- Netherton, S., Milenkovic, V., Taylor, M., & Davis, P. J. (2019). Diagnostic accuracy of eFAST in the trauma patient: a systematic review and meta-analysis. Canadian Journal of Emergency Medicine, 21(6), 2019. https://doi.org/10.1017/cem.2019.381
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- American College of Surgeons Committee on Trauma (1997) Advanced Trauma Life Support Course for Physicians. American College of Surgeons, Chicago. https://doi.org/10.1056/NEJMra0909487
- Moore CL & Copel JA. (2011). Point-of-care ultrasonography. New England Journal of Medicine, 364, 749-757. https://doi.org/10.1056/NEJMra0909487
- Wongwaisayawan, S, Suwannanon R, Prachanukool T, Sricharoen P, Saksobhavivat N, Kaewlai R. (2015). Trauma ultrasound. Ultrasound in Medicine & Biology, 41(10), 2543-2561. https://doi.org/10.1016/j.ultrasmedbio.2015.05.009
- Williams SR, Perera P, & Gharahbaghian R. (2014). The FAST and E-FAST in 2013: Trauma ultrasonography: Overview, practical techniques, controversies, and new frontiers. Critical Care Clinics, 30(1), 119-150. https://doi.org/10.1016/j.ccc.2013.08.005
- Husain, L.F. et al. (2012). Sonographic diagnosis of pneumothorax. Journal of Emergencies, Trauma, and Shock, 5(1), 76-81. https://doi.org/10.4103/0974-2700.93116
- Jang T, Kryder G, Sineff S, Naunheim R, Aubin C, Kaji AH. (2012). The technical errors of physicians learning to perform focused assessment with sonography in trauma. Academic Emergency Medicine, 19, 98-101. https://doi.org/10.1111/j.1553-2712.2011.01242.x
- Armstrong W. F., Schilt B. F., Helper D. J., Dillon J. C., Feigenbaum H. Diastolic collapse of the right ventricle with cardiac tamponade: an echocardiographic study. Circulation. 1982;65(7):1491–1496. https://doi.org/10.1161/01.cir.65.7.1491
- Whye D, Barish R, Almquist T, Groleau G, Tso E, Browne B. Echocardiographic diagnosis of acute pericardial effusion in penetrating chest trauma. Am J Emerg Med. 1988 Jan;6(1):21-3. https://doi.org/10.1016/0735-6757(88)90198-2
- Montoya J, Stawicki SP, Evans DC, Bahner DP, Sparks S, Sharpe RP, & Cipolla J. (2015). From FAST to E-FAST: an overview of the evolution of ultrasound-based traumatic injury assessment. European Journal of Trauma and Emergency Surgery, 42, 119-126. https://doi.org/10.1007/s00068-015-0512-1
- Lobo V, Hunter-Behrend M, Cullnan E, et al. Caudal Edge of the Liver in the Right Upper Quadrant (RUQ) View Is the Most Sensitive Area for Free Fluid on the FAST Exam. West J Emerg Med. 2017;18(2):270‐280. https://doi.org/10.5811/westjem.2016.11.30435
- ACEP. (2009). EFAST--Extended Focused Assessment with Sonography for Trauma. ACEP Now. https://www.acepnow.com/article/efast-extended-focused-assessment-sonography-trauma/?singlepage=1.
- Jehle, D. V. K., Stiller, G., & Wagner, D. (2003). Sensitivity in detecting free intraperitoneal fluid with the pelvic views of the FAST exam. The American Journal of Emergency Medicine, 21(6), 476-478. https://doi.org/10.1016/s0735-6757(03)00162-1
- Lichtenstein, D., Meziere, G., Biderman, P., & Gepner, A. (2000). The “lung point”: an ultrasound sign specific to pneumothorax. Intensive Care Medicine, 26(10), 1434-40. https://doi.org/10.1007/s001340000627
- Rahmani, F., Parsian, Z., Shahsavarinia, K., Pouraghaei, M., Negargar, S., Esfanjan, R. M., & Soleimanpour, H. (2017). Diagnostic value of sonography for confirmation of endotracheal intubation in the emergency department. Anesthesiology and Pain Medicine, 7(6), e58350. https://doi.org/10.5812/aapm.58350
- ACEP. (2016). Policy Statement: Ultrasound Guidelines: Emergency, Point-of-Care and Clinical Ultrasound Guidelines in Medicine. Ann Emerg Med. 2017;69(5):e27-e54. https://doi.org/10.1016/j.annemergmed.2016.08.457
- Chiu WC, Cushing BM, Rodriguez A, Ho SM, Mirvis SE< Shanmuganathan K, & Stein M. (1997). Abdominal injuries without hemoperitoneum: A potential limitation of focused abdominal sonography for trauma (FAST). Journal of Trauma and Acute Care Surgery, 42, 617-623. https://doi.org/10.1097/00005373-199704000-00006
- Miller MT, Pasquale MD, Bromberg WJ, Wasser TE, & Cox J. (2003). Not so FAST. Journal of Trauma and Acute Care Surgery, 54, 52-59. https://doi.org/10.1097/00005373-200301000-00007
- Kumar S, Bansal VK, Muduly DK, et al. Accuracy of Focused Assessment with Sonography for Trauma (FAST) in Blunt Trauma Abdomen-A Prospective Study. Indian J Surg. 2015;77(Suppl 2):393‐397. https://doi.org/10.1007/s12262-013-0851-2
- Quinn AC & Sinert R. (2011). What is the utility of the focused assessment with sonography in trauma (FAST) exam in penetrating torso trauma? Injury, 42, 482-487. https://doi.org/10.1016/j.injury.2010.07.249
- Engles, S., Saini, N. S., & Rathore, S. (2019). Emergency focused assessment with sonography in blunt trauma abdomen. International Journal of Applied and Basic Medical Research, 9(4), 193-196. https://doi.org/10.4103/ijabmr.IJABMR_273_19
- Stengel D, Leisterer J, Ferrada P, Ekkernkamp A, Mutze S, Hoenning A. (2018). Point-of-care ultrasonography for diagnosing thoracoabdominal injuries in patients with blunt trauma. Cochrane Database of Systematic Reviews, 12(12), CD012669. https://doi.org/10.1002/14651858.CD012669.pub2
- Abdulrahman, Y., Musthafa, S., Hakim, S.Y. et al. Utility of Extended FAST in Blunt Chest Trauma: Is it the Time to be Used in the ATLS Algorithm?. World J Surg 39, 172–178 (2015). https://doi.org/10.1007/s00268-014-2781-y
- Blaivas M, Lyon M, Duggal S. (2005). A prospective comparison of supine chest radiography and bedside ultrasound for the diagnosis of traumatic pneumothorax. Academic Emergency Medicine, 12(9), 844-9. https://doi.org/10.1197/j.aem.2005.05.005
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- Leichtle, S., Lucas, J. W., Kim, W. C., & Aboutanos, M. (2019). Decreasing accuracy of the eFAST examination - Another challenge due to morbid obesity. The American Surgeon, 85(8), 923-926. PMID: 31560313.
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- Melniker, L.A. The value of focused assessment with sonography in trauma examination for the need for operative intervention in blunt torso trauma: a rebuttal to “emergency ultrasound-based algorithms for diagnosing blunt abdominal trauma (review)”, from the Cochrane Collaboration. Crit Ultrasound J 1, 73–84 (2009). https://doi.org/10.1007/s13089-009-0014-7
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Cite this articleNadim Michael Hafez, MD, Kristin Lewis, MD, MA, Daven Patel, MD, MPH, Allyson Peterson, MD. Extended focused assessment with sonography for trauma (efast) exam. J Med Insight. 2021;2021(299.6). https://doi.org/10.24296/jomi/299.6
Table of Contents
- Probe Selection
- Probe Placement and Image Acquisition
- Image Optimization
- Pitfalls and Pearls
- Probe Selection
- Probe Placement and Image Acquisition
- Image Optimization
- Pitfalls and Pearls
- Probe Selection
- Probe Placement and Image Acquisition
- Image Optimization
- Pitfalls and Pearls
- Probe Selection
- Probe Placement and Image Acquisition
- Image Optimization
- Pitfalls and Pearls
- Probe Selection
- Probe Placement and Image Acquisition
- Image Optimization
- Pitfalls and Pearls
Hi, I'm Dr. Nadim Michael Hafez of the University of Chicago, and we're here today to discuss the focused assessment with sonography in trauma as well as the extended focus assessment with sonography in trauma. Although this exam has been in use since the early to mid '70s in Europe, it became widely used in the US in the mid to late 1990s when Dr. Grace Riziki introduced it to the US with her landmark paper. Indications for the exam broadly speaking, and based on the American College of Emergency Physicians policy statements are to rapidly evaluate the torso for evidence of traumatic free fluid or pathological error suggestive of injury in the peritoneal, pericardial, and pleural cavities. Contraindications - there are no absolute contraindications to the FAST exam or EFAST exam; however, if extensive injury to a body area precludes you from ultrasounding that area that is a relative contraindication. Also, if the patient has to go for emergent laparotomy, that would also be considered a relative contraindication. However, even in the case of emergent laparotomy, you may want to take a minute to evaluate for pneumothorax, tension pneumothorax, or pericardial tamponade, which could be treated prior to the operating room. Sensitivity and specificity.A quick review of the literature will show that the sensitivity and specificity for the Fast and EFAST exams range broadly. However, this range is also influenced by the type of trauma - blunt abdominal trauma versus penetrating trauma, the hemodynamic status of the patient, as well as the area of the body being examined - either the intra-abdominal peritoneal cavity versus the thoracic cavity versus the pericardial space. Although we will not talk about specific sensitivities and specificities as related to the FAST and EFAST exam, we will discuss general trends in sensitivity and specificity. Broadly speaking, the exam is more specific than it is sensitive. It is more sensitive in blunt abdominal trauma for evaluation of the peritoneal cavity than it is for penetrating trauma. It is more sensitive and specific in evaluation for pathology when evaluating the pericardial space and the pleural space than when evaluating the peritoneal space. It is also more sensitive and specific when the patient is hemodynamically stable versus a patient that is hemodynamically unstable. Please note - as with all ultrasound examinations, the sensitivity and specificity varies dramatically based on operator skill level, as well as patient body habitus. This video will now evaluate the five components of the EFAST examination. It will do so by covering probe selection, probe placement and image acquisition, image optimization, as well as the pitfalls and pearls associated with each window. Always remember that all ultrasound examinations require a coupling gel between the probe and the patient in order to transduce the images as ultrasound waves cannot penetrate air. In all of these windows we'll be evaluating for free fluid. Free fluid is completely black and anechoic and usually has sharp and acute angles.
The first view we'll be covering is the subxiphoid or subcostal view, which evaluates for fluid in the pericardial space.
First, we'll talk about probe selection. Probe selection should either be the phased array probe or the curvilinear probe. Both of these probes are a low frequency, thus have a long wavelength that penetrate well into the body. Whichever probe you choose, you should continue the exam with the same probe.
Probe placement. First we'll find the probe indicator. We'll take the probe indicator and align it to the patient's right. Then we'll identify the patient's xiphoid process, find the subcostal margin, place the probe right below the xiphoid process in the costal margin with the indicator to the patient's right, and then we will angle our beam directly at the patient's heart. As you can see, I've outlined roughly where Tim's heart would be. And then if you look at the screen, you can see where the heart is located on the screen. Right here, you got the right ventricle, the left ventricle, and on top you have the liver.
What we're going to do is we're going to do a quick couple of adjustments here just to optimize the picture, and that will just require adjusting the depth so that we have a full view of the heart, and adjusting the gain so that everything that's in the chamber space appears anechoic and black so that we know that we can identify free anechoic black fluid. So to orient you here, this is the patient's right as our indicator's to the right, this is the patient's left, right? This is the patient's subxiphoid or subcostal margin, and this is cephalad. The heart sits with the right ventricle angled slightly anterior and towards the probe, and the left ventricle superior and posterior. So you can clearly see liver and right ventricle, and that's the area where you're looking to identify free fluid in the pericardium.
Now we'll discuss some pitfalls and pearls of the pericardial subcostal view. Pitfall number one is failure to utilize the liver to help you view the heart. The liver is the sonographic window to the body. So if you're having trouble seeing the heart, the best thing you can do is come into the subcostal margin, come over a little bit to the right, and use that liver to visualize your heart. The second most common pitfall is the angle of the probe. A lot of novice and sonographers will start out to evaluate for the subcostal pericardial view by angling the probe too inferior. What they're doing is they're creating an acute angle between the patient's skin and the probe, and what they need to do is they need to lay it down and flatten out the probe. A great way to remember this is that your mother told you never to hold a spoon like this, but in this case, you get the hold the spoon like this because what you're trying to do is you're trying to scoop the patient's heart out. So think about angling down or lying flat and then scooping the patient's heart out, and you'll get a great view of the heart. Pearls - if you're unable to identify the subxiphoid / subcostal view for evaluation of the pericardial space by the subcostal approach, consider switching to what is known as the parasternal long approach. You can do this with, again, the curvilinear probe or with the phased array probe. Both probes will be able to do this view. And what you're going to do is you're going to take the gel from the subcostal space, you're going to find the second or third intercostal space. Parasternally on the left, you're going to place your indicator towards the patient's right shoulder and you're going to place the probe perpendicular on the patient's chest. Then you're going to come down one interspace at a time until you find cardiac activity. As you can see on the screen, we have cardiac activity, so what we're going to do now is we're going to adjust the depth to optimize our image. And what we want is you want this circle down here, this black circle, which is the descending thoracic aorta, to be the last thing that we have in view, you'll see the left atrium, the mitral valve, the left ventricle, the left ventricular outflow tract, the aortic valve, the ascending aorta, and the right ventricle. In this view, free fluid, or pericardial fluid, is located at the bottom of the picture. As in this case, you can tell that this is the top of the patient, or anterior, and this is deep and posterior. So by gravity fluid would become posterior and it should layer out back here. Things to remember about this view that's very important is that even though fluid is present, that fluid may not be causing tamponade or obstructive shock, so you need to evaluate for right ventricular collapse during diastole, which is the sign that we're looking for to evaluate and find tamponade and obstructive shock.
We'll now discuss the right upper quadrant view of the EFAST examination.
Probe selection for this view could either be the curvilinear or the phased array probe. Both of these probes have low frequencies and long wavelengths, allowing them to penetrate deep into the body.
Probe placement and image acquisition. We're going to take the probe and we're going to take the indicator on the probe, and we're going to align that indicator with the patient's head. So the indicator on the probe is going to be facing towards the patient's head. We're going to identify the anterior axillary line on Tim, the posterior axillary line, and the midaxillary line. We'll start the exam in the 8th through 11th rib space, right about the level of xiphoid and the midaxillary line. So I'm going to place my probe there - a little cold gel. And then we're going to aim posteriorly at the spine. And what we're looking for is what we found on the screen. We're looking for the patient's kidney and the liver. The interface between the kidney and the liver is a potential space known as Morison's pouch. There is no actual pouch, the kidney is retroperitoneal, and the liver is intraperitoneal. So the liver, when the patient's supine, is lying on that posterior peritoneal reflection that the kidney has made from the retroperitoneum into the peritoneum. What happens is if we put fluid into his peritoneum, the liver just lifts off of the kidney. There is no attachment between the kidney and the liver in the right upper quadrant, or hepatorenal view. Some structures that we can see here are the kidney, the liver, and the diaphragm, as well as these white bumps that represent Tim's spine.
Image optimization. We'll talk about image optimization of the right upper quadrant view. In order to optimize this image, we're going to properly set our depth and gain. So what we're going to do is we're going to adjust this so that the bottom of the image is the spine, and that we're able to see diaphragm, and that we're able to see both the kidney, and that we're going to be able to see the liver as well. While evaluating the right upper quadrant for free fluid, what we're looking for is again anechoic black fluid that shows up with acute angles, and what we're looking for is we're going to look for it between the kidney and the liver. The other space that we're evaluating here is the hemithorax. Tim, take a deep breath in. As he takes a deep breath in, you can see the diaphragm move inferiorly. So just to reorient you, this is the patient's head, this is the patient's foot, this is the patient's right side, and this is down and towards the left. So as Tim takes a breath, you'll see his lungs inflate.And what happens is because air cannot penetrate - or ultrasound cannot penetrate air - go ahead and exhale. There is a loss of the picture. So go ahead - inhale - we can see less, and then when he exhales, we can see more. Right? Because we cannot image through the lung. Now, as you can tell, you have the white line of the diaphragm there, and it looks like there's gray liver above and below the diaphragm. We know there's no liver above. This is caused by something known as a mirror image artifact. This artifact is a normal artifact. All imaging of the lung is usually either the presence or the absence of an artifact. The artifact can be normal, as in this mirror image artifact, or the artifact can be abnormal and represent pathology.So we're able to see if there is trauma to the hemithorax; if there is a hemothorax, we should be able to see a black area of fluid behind the diaphragm. Because that black fluid allows us to image further into the body regardless of how deep he takes a breath, we'll be able to see the spinal bumps continue off the screen. That's called a spine sign. So a positive spine sign would represent fluid in the hemithorax - in case of trauma, a hemothorax. Go ahead and take a deep breath. And the mirror image artifact itself - go ahead and exhale - which shows liver above and below this curved white line, which is the diaphragm is normal and rules out fluid in the hemithoraces.
We'll now discuss pitfalls and pearls of the right upper quadrant view of the EFAST examination. Pitfall number one - most novice sonographers will angle the transducer too horizontally and forget to lift up and aim down and towards the spine. By aiming horizontally, they're able to see the inferior vena cava and the liver but are unable to find the border between the kidney and the liver, or Morison's pouch. Pitfall number two - most novice sonographers place the transducer on the anterior axillary line instead of the posterior axillary line. What happens then is that you have to image through bowel, as you see here, and then you get gas shadow so you're able to not see the real interface between the kidney and the liver, or Morison's pouch, because you started too high on the body. Pitfall number three is acquiring a view of Morison's pouch without scanning through the inferior tip of the liver. This is the patient's head, this is the patient's foot, this is the patient's right side, and this is down and to the left. Fluid will collect on the inferior tip around the liver's inferior tip before it collects in Morison's pouch. So if you have this view, you might be missing fluid up here. In order to get past that what you're going to do is you're going to take your hand and you're going to rock the probe down towards the patient's foot. That's basically just turning along the curvature of the probe and aiming the beams towards the patient's feet. You're going to find the inferior triangular tip of that liver and then you're going to scan through it. What you're looking for, again, is free anechoic black fluid, which would represent blood in the case of a traumatic injury.The last pitfall we'll discuss is mistaking edge artifact for free fluid. When evaluating the right upper quadrant view of Morrison's pouch, it can often be a minimal black shadow that appears between the kidney and the liver edge. This usually appears somewhere along this area. If you notice though, if I go and look at the inferior liver edge, and I fan through that liver edge, there is no fluid around there. Any fluid that is to the left on the screen, or the patient's head in this case, right? This is his head, and this his foot, but does not pool around the liver edge cannot be free fluid. By gravity, free fluid has to collect in the most gravitational dependent area, which is around this liver tip. So if you find any kind of black anechoic stripe here, but then when you go down by rocking the probe and fanning around the liver edge, if you don't see that, that cannot be free fluid. One pearl is to take your indicator on your probe and instead of just angling it to the head is to rotate it and align it with the ribs. As you can tell we're getting rib shadow from the top of the screen, but if I take the transducer indicator, and instead of just aiming it straight up, I aim it towards the actual bed, I'm able to go in between the ribs and eliminate these shadows. Pearl number two for the right upper quadrant. Once evaluating the right upper quadrant, if you have trouble finding the diaphragm, slide your transducer up and down on the patient's body until you've optimized the image and got a good mirror image artifact, or lack thereof, or positive spine sign to evaluate the hemithorax.
We'll now discuss the left upper quadrant view of the EFAST examination.
Probe selection for the left upper quadrant view of the FAST exam include the phased array probe or the curvilinear probe. Again, both probes have a low frequency, long wavelength, and thus penetrate deep into the body. Whichever probe you choose, continue the rest of the examination with the same probe.
Probe placement and image acquisition for the left upper quadrant. First, identify the patient's left anterior axillary line, midaxillary line, and posterior axillary line. In the left posterior axillary line between the 7th and 10th intercostal space, place the probe with the indicator towards the patient's head. You'll obtain an image of the left kidney and the spleen, or the splenorenal left upper quadrant view. We're looking for black anechoic fluid between the spleen and the kidney.
Image optimization for the left upper quadrant. Once you've obtained a view of the left upper quadrant, make sure to adjust both depth and gain in order to optimize the image. So what you're going to do is you're going to want to have the kidney and the spleen in view, and then hopefully be able to see the bumps of the spine and the diaphragm as well. And make sure to adjust your gain accordingly. While imaging the left upper quadrant, it's important to remember that the spleen and the left kidney are anchored by the splenorenal ligament. That means that when fluid accumulates between both the spleen and the kidney, it will not separate the spleen completely from the kidney, as it does in the right upper quadrant. In the right upper quadrant, the retroperitoneal kidney and the intraperitoneal liver are not anchored as the spleen and the kidney are here. Fluid will accumulate around the inferior border of the spleen, and it will track in this direction superiorly towards the diaphragm.
Pitfalls and pearls. Common pitfalls of the left upper quadrant include failure to place the transducer on the posterior axillary line. Most novice [sonographers] will start with the transducer too high in the midaxillary line, allowing them to visualize the spleen but not allowing them to visualize the kidney and the spleen. Another pitfall of the left upper quadrant view is that the novice sonographer fails to realize that the kidney and the spleen are anchored. They'll obtain a view such as this where you can see kidney and spleen but not see the inferior tip of the spleen. Pearls for the left upper quadrant view of the FAST exam. Probably the easiest one is probe positioning. Take your thumb, place it on the underside of the probe, and your index finger at the top. Now rotate your hand around. Place your knuckles in the stretcher of the bed and place the probe with the indicator towards the patient's head in the posterior axillary line. This aligns the probe from posterior to anterior angled towards the spine, allowing you to find the paraspinal kidney. Once you've had correct probe placement and you've found an image that resembles this image up here with kidney and spleen, go ahead and slide superior and inferior on the patient in order to optimize your view. This is a good view as it shows the inferior tip of the spleen where fluid collects first and it shows the diaphragm as well as a spine, allowing us to view the left side mirror Image, which is spleen on both sides of the diaphragm. As with the right upper quadrant, you can evaluate the left upper quadrant to see fluid in the hemithoraces, so to look for a hemothorax on the left, we would again look for the spine to continue off the screen here, instead of having the spine stop at the diaphragm, and seeing spleen on both sides of the diaphragm.
We'll now discuss the suprapubic view of the EFAST exam.
Probe selection for the suprapubic of the EFAST exam include the phased array and curvilinear probes. Both probes are low frequency, long wavelength and allow you to penetrate deep into the body.
Probe placement for the pelvic view of the FAST exam is to take the probe with the indicator towards the patient's right in the suprapubic area perpendicular to the patient's abdominal wall. You will then tilt the probe, or fan it, down into the pelvis. We'll get a view of his bladder. Tim's pelvic view shows his bladder and his prostate. You're going to first fan through the bladder and prostate in the transverse axial plane with the indicator to the patient's right. Next you'll rotate 90 degrees, putting the indicator towards the patient's head for a sagittal longitudinal view, and you will fan from left to right, or right to left, in order to gain an entire view of the pelvis. Again, you're looking for anechoic black fluid, which would have sharp acute angles.
Image optimization. Remember that once you've acquired the image, you want to make sure you adjust the image to have the proper depth. In this case, you want to be able to see bladder, prostate, and the pelvis beyond both structures. And then make sure you adjust the gain to allow you to view anechoic black urine as well as possible free anechoic black fluid.
Pitfalls and pearls. A common pitfall to the pelvic view is to start the examination in an infraumbilical location rather than a suprapubic location. This is too high and requires you to look through bowel gas, which will scatter your beams and not allow you to see the bladder and thus the pelvis. You're using the bladder as a window to view the pelvis. If you start too high, you will not be able to catch the bladder and not be able to view the pelvis. A second pitfall is to fail to remember that fluid accumulates in different areas in both a male and female pelvis. In Tim's pelvis, as we take a look, we see the bladder and then the prostate. Fluid will accumulate behind the bladder between the bladder and the prostate. In a female pelvis, you'll have the bladder, if they haven't had a hysterectomy the uterus, and then the bowel. And fluid will accumulate behind the uterus in the rectouterine pouch of Douglas. Another pitfall is to forget that fluid that we're looking for is free fluid, which is black anechoic, much like the urine, but it has sharp angles. Oftentimes, these dark spaces, which are really bowel and gas, as there's a hyperechoic area, and then a grayish, blackish shadow is mistaken for free fluid. Remember that gas lets you see less and fluid lets you see more. So if I were to fill Tim's pelvis up with fluid, I would be able to see more rather than less. It would outline all of his bowel, it would outline his bladder, his prostate, and his rectum. So I'd be able to see all of the parts more clearly. If you don't see anything, and it looks black that doesn't necessarily indicate that there's free fluid, as much as it more indicates that there's likely to be gas. Free fluid shows you more rather than less. Pearls of the pelvic view. When evaluating the pelvis, you'll notice that the area behind the bladder is brighter than the adjacent areas. This is due to an artifact known as posterior acoustic enhancement. Any fluid-filled structure shows the area behind it to be brighter because the beams that went through the fluid-filled structure come back stronger and thus are interpreted as brighter by the ultrasound machine. This is an artifact that can be compensated for by using your time gain compensation. Just turn the gain and the backfield down, and you're able to identify free fluid more easily.
We'll now discuss the pleural view of the FAST exam, which evaluates for the presence or absence of a pneumothorax. Specifically, what we're looking for is a tension pneumothorax.
Probe selection for the pleural view can either be the linear high frequency probe, the phased array probe, or the curvilinear probe. Remember that when using the phased array and curvilinear probe, you'll have to decrease the depth in order to view the pleural line. And when using the linear probe, you're going to have to switch to either the curvilinear or the phased array probe for the remainder of the exam.
Probe placement for the pleural view of the FAST exam is the 2nd to 3rd intercostal space. The indicator is placed towards the patient's head. We'll get an image of such. We'll identify your rib with its corresponding shadow. And we'll try to put two ribs on the screen and find the pleural space beneath it and see the pleural line, which is going back and forth. This is the visceral and parietal pleura as they are opposed to each other with a small amount of fluid in between that we can't see. And when Tim takes a deep breath, we can see the line going horizontally back and forth. As we would see with normal pleural sliding. What we're looking for here is either the absence of this sliding, which would indicate the possibility of air between the visceral and parietal pleura, or sliding to a certain point, which would be known as a lung point, which is the point at which the collapsed lung is entering our view, and then leaving our view every time the patient takes a breath in and out. An adjunct to using either the linear, or curvilinear, or phased array probe when evaluating the pleural spaces, is to use M mode. M mode is motion over time. It takes a sample line and displays motion in a vertical direction over time in a horizontal direction. We can see our pleural line is about 1.5 cm down. So at 1.5 cm, everything above is linear, and everything below is slightly grainy. And that has to do with the fact that you cannot image lung. You can only see the presence or absence of an artifact as we discussed. Right as Tim takes a breath, it is normal to have linear on top and grainy on the bottom. That is called the seashore sign. If Tim had a pneumothorax, what I'd expect to see is I'd expect to see a barcode sign. So everything would look kind of linear like it does at just the top of the screen.
Image optimization for the pleural view revolves mostly around either using M mode or making sure you adjust the depth on the curvilinear and phased array probes in order to clearly visualize the pleural line.
Pitfalls and pearls. Pitfall number one is failure to adjust the depth on either the curvilinear or phased array probe. If you take a look at his pleural space with a curvilinear probe, you'll notice immediately that the preset depth for a FAST exam places you at about 15 cm. The pleural line is rather small and the motion is not very visible. Decreasing the depth in order to increase visibility of the pleural line is necessary, as you would fail to recognize lung sliding otherwise. Pitfall number two on the pleural view of the EFAST examination is failure to use M mode to evaluate for a pneumothorax. Pitfall number three is failure to realize that while using the M mode to identify lung sliding in a patient that has been intubated that there may be absence of lung sliding on the left hemithorax due to a mainstem intubation. If you mainstem intubate the patient, you're only ventilating the right hemithorax, and thus there's no movement of the pleural line on the left. And that would lead you to believe that the left lung is collapsed and may make you falsely place a chest tube on the left. What you're looking for in that case is a lung point, which would be an area where you have lung sliding in only one point in the M mode. So the M mode picture would look like a barcode sign everywhere, so everything would look very linear. And then we'd have a tower or strip of beach that would come up every once in a while, when the lung that is collapsed inflates to the point of being in the M mode view and then out of the M mode view. Pearls for the pleural view of the EFAST examination are to use M mode. M mode can be very helpful in identifying pleural movement, the absence of pleural movement, a lung point, or a barcode sign. A lung point is the most sensitive and specific thing for pneumothorax as it can help on both the left and the right side in order to evaluate for a pneumothorax. The absence of lung siding on the left as previously mentioned, does not rule in a pneumothorax. Pearl number two for the pleural view is to remember to move the probe up and down on the patient. Start in the 2nd intercostal space and scan from 2nd to 4th, and back to 2nd to see if you can find a large pneumothorax.