Focused Assessment with Sonography in Trauma (FAST): An Overview

Traumatic injuries are one of the leading causes of death, and intraperitoneal bleeds occur in approximately 12% of blunt traumas [1]. A quick assessment of trauma and detection of intraperitoneal fluid is increasingly essential in trauma patients’ assessment. The implementation of point-of-care ultrasound (POCUS) has had a significant impact on patient management, especially in a trauma setting. POCUS is easy to use at the bedside, non-invasive and inexpensive.

The Focused Assessment with Sonography in Trauma (FAST) is an ultrasound protocol used to assess hemoperitoneum and hemopericardium [2]. The FAST protocol is sensitive and specific for detecting intraperitoneal free fluid. According to previous studies, sensitivity ranges from 75-100%, and specificity ranges from 88-100% [3]. The FAST exam is rapid and can be completed in less than 5 minutes. It also has multiple advantages, including decreased time to interventions like surgery and length of stay at the hospital [4]. The Extended FAST (eFAST) protocol, which involves examinations of each hemithorax for hemothorax and pneumothoraces, has recently been introduced by several institutions [2].

Regions Examined

The FAST exam assesses the pericardium and multiple potential spaces within the peritoneal cavity for free fluid. The patient is often assessed in the supine position.

The right flank or right upper quadrant (RUQ) view assesses the hepatorenal recess (also known as Morrison’s pouch), as well as the right paracolic gutter, the hepato-diaphragmatic area, and the caudal edge of the left liver lobe [2]. The pericardial view, also known as the subcostal or the subxiphoid, is usually assessed next. The liver is commonly used as a sonographic window of the heart to evaluate pericardium. Ultrasound can detect little pericardial fluid with sensitivity and specificity approaching 100% [5]. The pericardial view also helps to differentiate between pleural and pericardial effusions and visualize right ventricular collapse during diastole [2]. Next, the left upper quadrant (LUQ) is used to visualize the splenorenal recess, the subphrenic space and the left paracolic gutter. If the eFAST protocol is being conducted, the RUQ and LUQ views are also used to examine the left and right hemithorax. Lastly, the pelvic or the suprapubic view is used to assess for free fluid in the rectovesical pouch in males and rectouterine and vesicouterine pouches in women [2]. The bladder acts as a sonographic window for this view.


While there are no complications related to the FAST exam itself, the use of ultrasound does have some limitations, one of which is the requirement for at least 150-200 cc of intraperitoneal fluid for an ultrasound to be able to detect. This can lead to false negatives when free fluid is in fact present [6]. False positives in the FAST exam may also occur and can be due to the presence of ascites, pre-existing pleural or pericardial effusions unrelated to the trauma, ruptured ovarian cysts or ruptured ectopic pregnancies [2]. Healthcare workers should be aware that POCUS and the FAST protocol have limitations dependent on the provider’s experience and the patient’s body habitus.   

Further Reading and Free Online Course


  1. Poletti, P. A., Mirvis, S. E., Shanmuganathan, K., Takada, T., Killeen, K. L., Perlmutter, D., Hahn, J., & Mermillod, B. (2004). Blunt abdominal trauma patients: can organ injury be excluded without performing computed tomography?. The Journal of Trauma57(5), 1072–1081.
  2. Bloom, B. A., & Gibbons, R. C. (2020). Focused Assessment with Sonography for Trauma.
  3. Brenchley, J., Walker, A., Sloan, J. P., Hassan, T. B., & Venables, H. (2006). Evaluation of focussed assessment with sonography in trauma (FAST) by UK emergency physicians. Emergency Medicine Journal23(6), 446–448.
  4. Melniker, L. A., Leibner, E., McKenney, M. G., Lopez, P., Briggs, W. M., & Mancuso, C. A. (2006). Randomized controlled clinical trial of point-of-care, limited ultrasonography for trauma in the emergency department: the first sonography outcomes assessment program trial. Annals of Emergency Medicine48(3), 227–235.
  5. Mandavia, D. P., Hoffner, R. J., Mahaney, K., & Henderson, S. O. (2001). Bedside echocardiography by emergency physicians. Annals of emergency medicine38(4), 377–382.
  6. Von Kuenssberg Jehle, D., Stiller, G., & Wagner, D. (2003). Sensitivity in detecting free intraperitoneal fluid with the pelvic views of the FAST exam. The American journal of emergency medicine21(6), 476–478.
Cite this article as: Maryam Bagherzadeh, Canada, "Focused Assessment with Sonography in Trauma (FAST): An Overview," in International Emergency Medicine Education Project, September 20, 2021,, date accessed: September 30, 2022

Question Of The Day #5

question of the day
qod 5 trauma

Which of the following is the most appropriate next step in management for this patient‘s condition?

This patient has sustained blunt abdominal trauma from his seat belt. This is indicated by the linear area of ecchymoses, known as a “seat belt sign”. This is a worrisome physical exam finding that should raise a concern about a severe intra-abdominal injury. All trauma patients presenting to the emergency department should be assessed using an organized approach, including a primary survey (“ABCs”) followed by a secondary survey (more detailed physical examination). The FAST (Focused Assessment with Sonography in Trauma) examination is part of the primary survey in a trauma patient. Some sources abbreviate the primary survey in trauma as “ABCDEF”, which stands for Airway, Breathing, Circulation, Disability, Exposure, FAST exam. The primary survey attempts to identify any life-threatening diagnoses that need to be addressed in a time-sensitive manner. Examples include cardiac tamponade, tension pneumothorax, and intra-abdominal bleeding. The FAST exam includes 4 basic views: the right upper quadrant view (liver and right kidney), pelvis view (bladder), left upper quadrant view (spleen and left kidney), and cardiac/subxiphoid view (heart). An E-FAST, or extended FAST, includes the four standard FAST views plus bilateral views of the lungs to evaluate for pneumothorax. An abnormal FAST exam demonstrates the presence of free fluid on ultrasound. In the setting of trauma, free fluid is assumed to be blood. Free fluid on ultrasound appears black, or anechoic (indicated by yellow arrows in below image).

question of the day 5 trauma

The space between the liver and right kidney (“Morrison’s Pouch”) is often the first location or blood to accumulate in a patient with intra-abdominal bleeding. Trauma patients who are hemodynamically unstable with a positive FAST exam (this patient) should go to the operating room for emergent exploratory laparotomy (Choice C) to determine the source of their bleeding. Performing a CT scan of the abdomen and pelvis (Choice A) would be the correct answer if the patient was hemodynamically stable and had a positive FAST exam. Allowing this patient to leave the emergency department for a CT scan would be dangerous as this patient could rapidly decompensate. Performing a Diagnostic Peritoneal Lavage (Choice B) would be the correct answer if the patient was hemodynamically stable but had a normal FAST exam. An emergent thoracotomy (Choice D) is more typically performed in patients with penetrating trauma who have cardiac arrest shortly before presenting to the emergency department. This intervention attempts to identify and treat any reversible causes of cardiac arrest. Correct Answer: C


Butler, M. (2015). “Boring question: What is the role of the FAST exam for blunt abdominal trauma?” Canadiem.

Franzen, D. (2016). “FAST examination”. SAEM.

Cite this article as: Joseph Ciano, USA, "Question Of The Day #5," in International Emergency Medicine Education Project, July 22, 2020,, date accessed: September 30, 2022

From experts to our students! – eFAST