A 24-year-old G1P0010 female with a PMHx of ovarian cyst (unknown laterality) and emergency contraceptive use 3 months prior presented with sudden onset abdominal pain (upper > lower) that awoke her from sleep four hours prior to presentation with associated nausea and mild lower back pain. The pain is 10/10, sharp, stabbing, and diffuse. Additionally, she reported trace white vaginal discharge at baseline. No acute increase. She had intermittent vaginal bleeding since contraception use over the past two months, which has now resolved. She denied fever, chills, vomiting, chest pain, shortness of breath, diarrhea, or constipation. No pertinent surgical history.
An ideal RUQ ultrasound visualizes the liver, Morrison’s pouch, superior and inferior poles of the right kidney, and diaphragm in the coronal plane. Here, we see a thickened hepatic capsule, septations, and trace ascites.
Fitz-Hugh-Curtis syndrome (FHCS) is characterized by perihepatitis in the setting of pelvic inflammatory disease (PID). It traditionally presents with right upper abdominal pain with associated nausea, vomiting, and fever in women of childbearing age. While overall considered a rare manifestation of PID, the true incidence of FHCS is poorly defined in the literature . The pathophysiology of spread is also poorly understood. It is speculated that bacteria (N. gonorrhoeae, C. trachomatis) travel to the liver via blood, lymphatics or peritoneal fluid, causing perihepatitis . Diagnosing FHCS poses a diagnostic challenge to clinicians. Traditionally, the diagnosis is made via laparoscopic exploration of the abdomen with visualization of the characteristic “violin-string” adhesions, with growing evidence also supporting the use of contrast-enhanced CT . Limited evidence exists to support the use of ultrasonography in diagnosing FHCS. One case report published in 1993 used RUQ abdominal ultrasound to identify septations (violin-string adhesions) and ascites to ultimately diagnose FHCS, later confirmed by serologic and operative evidence . Another case report from 2018 used ultrasonography to identify a thickened hepatic capsule in an 18-year-old female with RUQ pain, later confirming FHCS by CT without the need for laparotomy . While more research is needed, identification of FHCS via bedside ultrasonography in the emergency setting followed by appropriate antibiotic therapy can be an effective approach to FHCS, ideally reserving laparoscopy only for lysis of adhesions in refractory cases.
Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric lung ultrasound. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.
List indications for performing a pediatric lung point-of-care ultrasound (POCUS).
Describe the technique for performing lung POCUS.
Recognize anatomical landmarks and artifacts related to lung POCUS.
Interpret signs of a consolidation, interstitial fluid, effusion, and pneumothorax on POCUS.
Describe the limitations of lung POCUS.
Child with Cough and Fever: Case Introduction
A 6-year-old boy presents to the emergency department complaining of cough for 3 days and fever for the last day. His fever was 103°F this morning and he received ibuprofen. He has also had abdominal and back pain. He was seen at the emergency department earlier in the day where he had a chest X-ray 6 hours prior that was interpreted as negative for consolidation and bloodwork including a complete blood count and comprehensive metabolic panel that were within normal limits. He presents with persistent cough and fever and now has increased work of breathing.
On arrival, his vital signs are:
Oxygen Saturation (room air)
He is well appearing but has increased work of breathing. His lungs have decreased breath sounds and crackles over the left lung base. No wheezes are appreciated. He has mild subcostal retractions. His abdomen is soft, non-tender, and non-distended. His back is non-tender to palpation. He has normal HEENT, neck, and cardiac examinations, with the exception of tachycardia as above.
Given his presenting signs and symptoms in the setting of a recent chest X-ray that was interpreted as normal, you decide to perform a lung point-of-care ultrasound (POCUS) examination.
Lung POCUS can be performed for a wide range of cardiorespiratory complaints including cough, fever, difficulty breathing, chest pain, hypoxia, and chest trauma. It can also facilitate early diagnosis, allowing for appropriate management. Children are excellent candidates for lung POCUS as they have thinner chest walls and smaller thoracic widths than adults.
The lungs were traditionally considered poorly accessible to ultrasound, as ultrasound waves cannot penetrate air-filled structures; however, lung POCUS relies on the interpretation of patterns of artifacts to evaluate the normal, air-filled lungs.
When there is lung pathology, the consolidation or fluid allows for direct visualization of the pathology with lung POCUS and replaces the air artifacts. Fluid in a consolidation or effusion is easily visualized with ultrasound if the fluid has direct contact with the pleural surface. As lung POCUS will only visualize the lung under the probe, it is essential to completely evaluate the lungs anteriorly, laterally, and posteriorly to avoid missing pathology.
Positioning and Probe
Figure 1: Younger children can sit in their parent’s lap and give a hug for lateral and posterior lung scanning.
The patient should be in a position of comfort: supine, sitting, or in parent’s lap (Figure 1).
Warm gel helps with the child’s comfort.
Distractions such as a toy, book, or phone/tablet can also help ease anxiety.
Use a linear high frequency probe. If increased depth is needed, such as in the evaluation for effusion, a curvilinear or phased array probe may also be used.
There are different protocols to scan the lung depending on the purpose of the evaluation. For example, in pneumothorax, we focus on the anterior chest where air rises in a supine patient, and for the extended Focused Assessment with Sonography (eFAST) exam, we focus on more dependent areas where pleural fluid or blood collects. Below we discuss the complete lung exam which is often used in evaluating for pneumonia.
Figure 2: The 6-zone lung scanning protocol includes anterior, lateral, and posterior lung fields bilaterally.
A 6-zone lung ultrasound protocol is used for a complete lung examination (Figure 2):
Anterior lungs bilaterally are scanned in the mid-clavicular line from the apex to the base of the lungs and diaphragm.
Lateral lungs bilaterally are scanned in the mid-axillary line from the apex to the base of the lungs and diaphragm.
Posterior lungs bilaterally are scanned medial to the scapulae and lateral to the vertebral bodies from the apex to the base of the lungs and diaphragm.
Place the probe longitudinally, perpendicular to the ribs, with the probe marker towards the patient’s head. Identify anatomical landmarks on ultrasound (Figure 3, Video 1).
Figure 3: Normal lung with A-lines in longitudinal (left) and transverse (right) orientations
Video 1: Normal lung POCUS in longitudinal orientation
Video 2: Normal lung POCUS in transverse orientation
Normal Lung Findings
Ribs: Hyperechoic, curvilinear structure with posterior acoustic shadowing
Pleural line: Hyperechoic line immediately deep to the ribs
Lung sliding sign: Visceral and parietal pleural are juxtaposed and sliding against each other with respirations, giving the pleural line a shimmering or “ants marching on a log” appearance. For additional examples, see the PEM POCUS Endotracheal Intubation Confirmation article, specifically in Section 2 – Indirect Confirmation: Visualize Bilateral Lung Sliding.
Lungs filled with air: Visualized on POCUS as horizontal A-lines, which are a reverberation artifact of the pleural line. The pleural line is reflected as the ultrasound beams bounce back and forth between the probe and the highly reflective pleural line, and therefore the distance between A-lines is the same as the distance between the probe and the pleural line (Figure 4).
Figure 4: Reverberation artifact and A-lines. The probe sends out ultrasound waves that bounce back and forth between the highly reflective pleural line and the probe (leftmost 3 arrows). The ultrasound machine then interprets these signals as A-lines equidistant from the pleural line (rightmost 3 arrows).
Figure 7: Lung POCUS with subpleural consolidation
Video 5: Lung POCUS with subpleural consolidation
Subpleural consolidations are small hypoechoic or tissue-like structures with pleural line abnormalities and blurred margins (Figure 7 and Video 5). They measure <1 cm and are usually seen with a viral process.
Lung pathology may be missed without a complete lung POCUS scanning protocol, as you will only see pathology located directly under the probe. The lung POCUS is also operator-dependent, and it has a steep learning curve.
POCUS can’t visualize a centrally located pneumonia not extending to the pleural surface. A lung consolidation needs to extend to the pleural surface to be visualized on lung POCUS.
However, a study in adult patients showed that 99% of lung consolidations extend to the pleura . Thus, in children with smaller lung mass, most consolidations likely will be detected by lung POCUS.
Left Lower Chest
Caution is needed at the left lower chest, as the spleen and air in the stomach can be misinterpreted as consolidation (Figure 11).
Locate the diaphragm in the left lower chest to be sure you are evaluating lung above the diaphragm.
Figure 11: The spleen and the stomach with air may be misinterpreted as consolidation.
In younger children, the thymus may be misinterpreted as a consolidation.
The thymus will be adjacent to the heart, have regular echotexture, no air bronchograms, and regular borders (Figure 12).
Figure 12: Thymus (*) located adjacent to the heart
There have been multiple studies of lung POCUS identifying pneumonia in children, and several meta-analyses have been published [2-4]. Table 1 summarizes these studies, showing an overall high accuracy for lung POCUS diagnosis of pneumonia in children.
Pereda et al., Pediatrics 2015
8 studies; 765 patients
Evidence supports lung POCUS as an alternative for diagnosis of pneumonia in children.
Balk et al., Pediatr Pulmonol 2018
12 studies; 1510 patients
Lung POCUS had significantly better sensitivity than chest X-ray, which had a sensitivity of 87%.
Tsou et al., Acad Emerg Med 2019
25 studies; 3353 patients
Significant difference in accuracy between novice and advanced sonographers.
Table 1. Meta-analyses of lung POCUS for diagnosis of pneumonia in children
1. Decreased radiation and length of stay
A randomized controlled trial comparing lung POCUS to chest X-ray for diagnosis of pneumonia showed a 39% reduction in chest X-ray utilization and a decreased emergency department length of stay from 180 to 132 minutes in the patients receiving only lung POCUS with no cases of missed pneumonia .
2. Best view for pneumonia
A study looking at lung consolidation locations in children with pneumonia found that 96% of pneumonias were detected by the transverse view, compared to 86% in the longitudinal view.
The authors concluded that the transverse orientation detects more pneumonia than the longitudinal view, and that omission of either orientation or any lung zone may miss pneumonia .
3. Pneumothorax: POCUS is better
A meta-analysis of chest X-ray vs ultrasound for diagnosis of pneumothorax showed that ultrasound had a sensitivity of 88% and specificity of 99% compared to sensitivity of 52% and specificity of 100% for chest X-ray. Furthermore, lung POCUS performed specifically by non-radiologist clinicians had a sensitivity of 89% and specificity of 99% .
The patient’s chest X-ray from earlier in the day was interpreted by the pediatric radiologist as negative for consolidation or other pulmonary pathology. You performed a lung POCUS with a linear, high-frequency probe and observed the following:
Video 9: A lung POCUS of the case patient’s left lower lung (affected side)
Though this child with cough, fever, focal lung findings, and respiratory distress had a negative chest X-ray performed 6 hours earlier, your POCUS evaluation identified a left lower lobe pneumonia which helped you make your diagnosis and start the appropriate treatment.
The patient received antibiotics for pneumonia. His work of breathing increased during his emergency department visit, and he was started on high flow nasal cannula at 30 L/min with improvement in his respiratory status. He was admitted to the pediatric intensive care unit. He had a repeat chest X-ray 12 hours later that was interpreted by the pediatric radiologist as having new pleural and parenchymal changes in the left hemithorax with questionable pneumonia. He continued antibiotics, and his repeat X-ray 48 hours later showed a clear left lower lobe consolidation with pleural effusion.
Lichtenstein DA, Lascols N, Mezière G, Gepner A. Ultrasound diagnosis of alveolar consolidation in the critically ill. Intensive Care Med. 2004 Feb;30(2):276-281. PMID: 14722643
Pereda MA, Chavez MA, Hooper-Miele CC, et al. Lung ultrasound for the diagnosis of pneumonia in children: a meta-analysis. Pediatrics. 2015 Apr;135(4):714-22. PMID: 25780071
Balk DS, Lee C, Schafer J, et al. Lung ultrasound compared to chest X-ray for diagnosis of pediatric pneumonia: A meta-analysis. Pediatr Pulmonol. 2018 Aug;53(8):1130-1139. PMID: 29696826
Tsou PY, Chen KP, Wang YH, et al. Diagnostic Accuracy of Lung Ultrasound Performed by Novice Versus Advanced Sonographers for Pneumonia in Children: A Systematic Review and Meta-analysis. Acad Emerg Med. 2019 Sep;26(9):1074-1088. PMID: 31211896
Jones BP, Tay ET, Elikashvili I, et al. Feasibility and Safety of Substituting Lung Ultrasonography for Chest Radiography When Diagnosing Pneumonia in Children: A Randomized Controlled Trial. Chest. 2016 Jul;150(1):131-8. PMID: 26923626
Ever finally step away from a busy resuscitation and someone stops you for peripheral IV access? You set up everything, have the patient positioned, and then notice there is no sterile ultrasound gel. No gel? No problem. The trick is to eliminate anything of poor acoustic impedance between the ultrasound probe and the patient’s skin.
Trick of the Trade
1. Apply a transparent adhesive dressing with a thin alcohol layer on the probe
2. Use sterile saline instead of gel on the patient’s skin
Squirt normal saline flush on the patient’s skin to create a coupling medium between the probe and the patient.
Why it works:
Ultrasound procedures use a range of frequencies (1.5-20 MHz) to visualize internal structures and require a medium to replace air, which has a poor acoustic impedance for the ultrasound waves . Acoustic impedance is defined as the resistance of the propagation of ultrasound waves through tissues and is the product of the density and speed of sound in the tissue . Ultrasound gel has an acoustic impedance that is similar to soft tissue and is therefore considered the ideal medium . Because most soft tissue is comprised of water, the acoustic impedance of water, and therefore 0.9% saline, is actually pretty similar , as demonstrated by water bath techniques for ultrasounding distal extremity injuries .
We find great visual clarity for performing ultrasound-guided peripheral IVs using this trick, as shown in Figure 1.
Figure 1: Peripheral IV ultrasound using alcohol under transparent film dressing and topical saline flush – all without ultrasound gel
Afzal S, Zahid M, Rehan ZA, et al. Preparation and Evaluation of Polymer-Based Ultrasound Gel and Its Application in Ultrasonography. Gels. 2022 Jan 6;8(1):42. doi: 10.3390/gels8010042. PMID: 35049577; PMCID: PMC8774352
Suzuko S, Peter G, Philipp L. 20 – Local Anesthetics, Ed(s): Hugh C. Hemmings, Talmage D. Egan, Pharmacology and Physiology for Anesthesia (Second Edition), Elsevier, 2019, Pages 390-411, ISBN 9780323481106. DOI: 10.1016/B978-0-323-48110-6.00020-X
R. Alkins, K. Hynynen, 10.08 – Ultrasound Therapy, Editor(s): Anders Brahme, Comprehensive Biomedical Physics, Elsevier, 2014, Pages 153-168, ISBN 9780444536334. DOI 10.1016/B978-0-444-53632-7.01010-8
An 8-year-old Caucasian male with no significant past medical history presented to the pediatric emergency department (ED) with complaints of three days of abdominal pain and dysuria, accompanied by nausea, vomiting, and poor oral intake. The patient had previously presented to his pediatrician, where he was found to have microscopic hematuria and subsequently sent to the ED. Microscopic hematuria and increased abdominal pain in the ED prompted a point of care ultrasound (POCUS).
The most likely site of abnormality in this patient is the urethra. Image 1 shows massive bilateral hydronephrosis while image 2 shows hydroureter and bladder wall thickening. This presentation in a male, together with the lab findings suggestive of a UTI, should raise concerns for posterior urethral valves (PUV). PUV, a congenital obstruction of the urethra, is one of the most common causes of lower urinary tract obstruction in males. 
The next step in management for patients with probable PUV is a referral to a urologist for a voiding cystourethrogram (VCUG) and cystoscopy to assess for vesicoureteral reflux and valvular obstruction. Patients who are found to have PUV can then undergo incision and correction of the urethral valve. PUV typically presents in the newborn period in males with a poor urinary stream, urinary tract infections, and other voiding complaints and can be corrected with bladder catheterization or valvular ablation [1,2].
While rare, PUV should be considered in the differential for any pediatric patient presenting with urinary tract-related complaints, abdominal pain, and unexplained nausea or vomiting, particularly in school-aged males.
A school-aged male without an underlying diagnosis presenting to the hospital with a UTI should prompt clinicians to look for underlying predisposing conditions, such as PUV – an undertaking in which bedside ultrasound can be extremely useful.
Point of care ultrasound (POCUS) is a tool used in real time by emergency physicians to provide evidence for hydronephrosis, which can lead to the diagnosis of PUV.
Hodges SJ, Patel B, McLorie G, Atala A. Posterior urethral valves. ScientificWorldJournal. 2009 Oct 14;9:1119-26. doi: 10.1100/tsw.2009.127. PMID: 19838598; PMCID: PMC5823193.
Shields LBE, White JT, Mohamed AZ, Peppas DS, Rosenberg E. Delayed Presentation of Urethral Valves: A Diagnosis That Should Be Suspected Despite a Normal Prenatal Ultrasound. Glob Pediatr Health. 2020 Oct 15;7:2333794X20958918. doi: 10.1177/2333794X20958918. PMID: 33117862; PMCID: PMC7570289.
A 48-year-old female with a past medical history of opioid use disorder on suboxone presents with abdominal pain for one day. The patient developed sharp diffuse upper abdominal pain the evening prior to arrival that resolved. The pain recurred again today and was associated with bilious emesis. The patient notes persistent upper abdominal pain with paroxysmal exacerbation. She has a history of a hysterectomy, but no other abdominal surgeries. No history of gallstone pathology.
An echo was performed for bradycardia and a brief episode of hypoxia in the emergency department. A large, tethered mass is seen likely originating from the left atrium. This finding is most consistent with an atrial myxoma, though it can also represent a clot. The patient was ultimately diagnosed with gallstone ileus and an atrial myxoma.
Read this tutorial on the use of point of care ultrasonography (POCUS) for Pediatric Focused Assessment with Sonography for Trauma. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.
Summarize the indications and role of the FAST in the evaluation of injured children
Describe the technique for performing the pediatric FAST
Identify anatomical views and landmarks necessary for a complete pediatric FAST
Accurately interpret each pediatric FAST anatomic view and corresponding landmarks
Describe the literature on the pediatric FAST
You receive an emergency medical services (EMS) notification that they are 2 minutes out from your ED with a 3-year-old boy who fell down a flight of 10 concrete stairs. He is awake and breathing spontaneously but irritable and crying with an obvious deformity to his right arm. EMS placed him in a cervical-collar and are bringing him to your ED.
Trauma remains the leading cause of childhood death and disability in children >1 year of age . While head and thoracic trauma account for most death and disability in children, missed abdominal injuries are a common cause of mortality . Particularly in polytrauma scenarios, it can be difficult for children to locate the exact area of pain and assessing for abdominal injury can be difficult.
FAST is a rapid ultrasound examination of 4 locations (Figure 1) with the primary objective of detecting free fluid within the abdomen, pleural space, and pericardial sac. In injured adults, FAST is useful in rapidly triaging hemodynamically unstable patients to expedite operative management . Free fluid in any one view deems the FAST positive. However, for a FAST to be determined as negative, each of the landmarks in each individual view must be interrogated and evaluated for the presence of free fluid. The role of FAST in the hemodynamically stable child after blunt abdominal trauma is nuanced.
Figure 1. Location of the 4 FAST views: Right upper quadrant (A), left upper quadrant (B), pelvic (C), subxiphoid (D). Illustration by Dr. Maytal Firnberg.
The FAST can be performed in parallel with the rest of the trauma evaluation. Serial FAST exams can be repeated as needed throughout the child’s ED stay, particularly if the child has an unexplained change in clinical status. For a complete FAST, each of the views needs to be assessed and every landmark in each view must be visualized. In addition to intra-abdominal hemorrhage and pericardial effusion, point-of-care ultrasound can be used to evaluate the thorax for hemothorax and pneumothorax. When included together, this exam is referred to as the extended FAST (E-FAST).
In general, the child should be positioned supine as free fluid will pool in dependent areas (Figure 2). In children, the recto-vesicular or recto-uterine pouch is the most common place for fluid to collect depending on the patient’s sex . Fluid in the abdomen can move freely up the right pericolic gutter into the right upper quadrant. The left pericolic gutter is higher and the phrenicocolic ligament blocks the flow; consequently, fluid tends to flow to the right pericolic area over the left, regardless of injury type.
Some controversy exists about how much free fluid can be detected by the FAST, and most studies focused on adults. For pediatric patients, we are using 100 mL as it was the median quantity of fluid needed for ultrasound detection of the pelvic view .
Figure 2. Free fluid accumulates in dependent areas. In a supine patient, this is the hepato-renal pouch (right upper quadrant view), the spleno-renal pouch (left upper quadrant view), and recto-vesicular or recto-uterine pouch (pelvic view). Illustration by Dr. Maytal Firnberg.
Use a low frequency ultrasound probe: phased array probe (Figure 3) or curvilinear probe (Figure 4).
Phased array probes can generally achieve adequate penetration particularly for smaller pediatric patients and have a smaller footprint allowing for easier intercostal views.
Curvilinear probes allow for further penetration and greater depth of abdominal views and may be useful in larger children.
For the 4 scanning areas, each view must be interrogated completely, and the clinician should identify all key landmarks. The red dot on the probe correlates with the probe marker.
Right Upper Quadrant (RUQ) View
Figure 5. Place the probe in the right mid axillary line (around ribs 8-10) with the probe marker towards the head. Fan anterior and posterior and slide up or down a rib space to view the key landmarks.
Normal View and Landmarks
Figure 6. Normal RUQ ultrasound view with labeled landmarks
Diaphragm (including the subdiaphragmatic intraperitoneal space and supradiaphragmatic intrathoracic space)
Liver (including the caudal tip of the liver)
Kidney (including superior and inferior poles)
Hepatorenal Recess (Morison’s Pouch) – A potential space between the liver and kidney where free fluid can collect
Normal Ultrasound Video
Video 1. Normal RUQ ultrasound view
Left Upper Quadrant (LUQ) View
Figure 7. Place the probe in the left mid or posterior axillary line (around ribs 7-9) with the probe maker towards the head. Fan anterior and posterior and slide up or down a rib space to view the landmarks. In infants and smaller children, the midaxillary line generally provides the best view.
Normal View and Landmarks
Figure 8. Normal LUQ ultrasound view with labeled landmarks
Diaphragm (including the sub- and supradiaphragmatic areas)
Spleen (including splenic tip)
Kidney (including superior and inferior poles)
Splenorenal Recess – a potential space between the spleen and kidney where free fluid can collect
Normal Ultrasound Video
Video 2. Normal LUQ ultrasound view
Figure 9. Place the probe in the midline below the umbilicus and fan or rock the probe down towards the feet until the bladder comes into view. Fan through the entire bladder in both transverse and sagittal orientations. For the transverse and sagittal views, the probe marker should be towards the patient’s right and head, respectively.
Normal View and Landmarks
Figure 10. Normal sagittal (left) and transverse (right) views of the pelvic ultrasound with labeled bladder
Bladder (including anterior and posterior walls)
In patients with uteruses, make sure to visualize the uterus and the recto-uterine space as fluid can collect between the bladder and uterus and also behind the uterus.
Normal Ultrasound Video
Video 3. Normal pelvic ultrasound view (sagittal)
Video 4. Normal pelvic ultrasound view (transverse)
Figure 11. Place the probe under the sternum for a subxiphoid view. Point the probe towards the left shoulder and the probe marker towards the right shoulder. This view requires gentle downward pressure as you drop the angle of the probe down towards the patient. If unable to obtain this subxiphoid view, look parasternally.
Normal View and Landmarks
Figure 12. Normal pericardial subxiphoid ultrasound view with labeled landmarks
Left and right ventricles (atria may also be visible)
Normal Ultrasound Video
Video 5. Normal pericardial ultrasound view (no pericardial effusion and normal contractility)
The aim of the FAST is to identify free fluid in the abdomen, pelvis, pleural, and pericardial spaces.
Free fluid will appear anechoic (black) and will pool in dependent, unobstructed areas. On the right side, fluid in the abdomen can move freely up the pericolic gutter into the right upper quadrant. On the left, the pericolic gutter is higher and the phrenicocolic ligament may impede its flow. The RUQ view is the most sensitive view in adults while the pelvic view is the most sensitive view in children . The following are examples of free fluid identified within the various views of the FAST scan.
Figure 13. RUQ ultrasound view demonstrating free fluid in Morrison’s pouch in an unlabelled (A) and labelled (B) image
Abnormal RUQ Views
Figures 14 (left) and 15 (right). Abnormal RUQ ultrasound views with free fluid. Note that the right image demonstrates free fluid both above and below the diaphragm, meaning fluid that is in the peritoneal and pleural cavities, respectively.
Video 6. Abnormal RUQ ultrasound view with free fluid in the pleural space and Morison’s pouch
Abnormal LUQ Views
Tip: In the LUQ view, the free fluid tends to collect just under the diaphragm. Be sure to look at the diaphragm-spleen interface.
Figure 16. Abnormal LUQ view with free fluid below the diaphragm and above the spleen
Video 7. Abnormal LUQ ultrasound view with free fluid under the diaphragm
Abnormal Pelvic Views
Tip: Free fluid can collect between the bladder and colon in male patients. In female patients, fluid can collect between the bladder and uterus or between the uterus and colon.
Figure 17. Abnormal pelvic view showing free fluid between the bladder and colon
Video 8. Abnormal pelvic ultrasound on sagittal view showing free fluid
These artifacts are cast above the diaphragm in the RUQ and LUQ views.
Figure 19. The RUQ view shows liver parenchyma architecture cephalad of the diaphragm as a mirror artifact.
The spine is not typically seen cephalad to the diaphragm by ultrasound due to air artifact. If the spine is visualized above the diaphragm, this indicates the lungs are no longer filled with air, which normally causes the refraction/reflection of ultrasound waves. This occurs in instances where air is replaced by fluid, such as a pleural effusion or hemothorax, or by a dense consolidation or contusion.
Figure 20. A – The spine is not visualized cephalad to the diaphragm in a normal RUQ ultrasound view. B – A pleural effusion results in a “spine sign” where the spine can be seen extended beyond the diaphragm.
Posterior Acoustic Enhancement
Since the bladder is a fluid filled structure which transmits ultrasound waves well, the waves illuminate the posterior wall of the bladder in a phenomenon called posterior acoustic enhancement. This brightness can hide free fluid settled in the pelvis. Thus, decrease the far field gain (brightness) behind the bladder to avoid missing obscured free fluid.
Figure 21. Bladder view with posterior acoustic enhancement artifact
As blood pools, the ultrasound appearance of clotted blood may have similar echotexture to surrounding soft tissue or organs rather than appear anechoic (black) as typical free fluid.
Figure 22. Bladder view showing hypoechoic clotted blood that may be confused as soft tissue
Due to ultrasound physics and sound wave transmission between structures of different densities, edge artifacts are seen as a dark thin line tracing off the edge of this interface extending to the bottom of the screen. It can be misinterpreted as free fluid.
Figure 23. RUQ view with an edge artifact
A full stomach will appear as a rounded collection of fluid and air anterior to the spleen. It may mimic a free fluid collection. Fan posterior of the stomach to visualize the spleen and perisplenic spaces.
Figure 24. The stomach obscures the LUQ view. Note the mix of bright (air) and dark (other gastric contents) inside the stomach.
Seminal vesicles can appear as hypoechoic, contained, symmetric structures posterior to the bladder in the transverse view and can be mistaken for free fluid.
Figure 25. Bladder view showing hypoechoic seminal vesicles posterior to the bladder
The FAST evaluates for the presence free fluid only .
In trauma, the assumption is that free fluid is due to hemorrhage; however, the FAST cannot adequately distinguish between blood and other types of free fluid, such as ascites or physiologic free fluid.
It does not directly evaluate for injury to solid organs, bowel, diaphragm, or retroperitoneum.
In isolation, the FAST cannot rule out intra-abdominal injury .
The FAST can not detect tiny amounts of hemorrhage.
The scan may appear initially negative with a free fluid volume under a threshold of about 100 mL .
Repeat FAST scans may help detect an accumulation of fluid over time throughout a child’s evaluation.
Trace pelvic free fluid may be physiologic in children, thus limiting specificity .
For adults, the FAST is integral in the diagnostic evaluation after blunt and penetrating trauma . It improves outcomesby decreasing the time to surgical intervention, patient length of stay, surgical complications, CT scan, and diagnostic peritoneal lavage rates .
For children, however, the literature is less clear cut. Pediatric injury patterns commonly result in solid organ lacerations without hemoperitoneum, making the FAST a less sensitive means for detecting important intra-abdominal injury . Further, the test characteristics of the FAST have variable reliability and accuracy in children [7,10,11]. This variation contributes to uncertainty of how to use results of the FAST and decreases its impact on potentially important clinical outcomes such as rates of CT scans and ED length of stay . However…
The FAST is able to identify injuries that the physical exam can miss. When combined with the physical exam, the FAST scan has been found to have better test characteristics than the physical exam alone .
The improvement in POCUS technology, widespread pediatric-specific POCUS expertise, and a focus on clinically relevant outcomes have allowed clinicians to integrate the FAST into novel diagnostic strategies for children after blunt torso trauma .
The pediatric FAST may be used in combination with signs, symptoms, and other diagnostic testing as a screening algorithm to decrease unnecessary CTs. Investigators will need to conduct larger validation trials to confirm and clarify the algorithm.
Studies that have shaped the pediatric FAST literature landscape:
Study Type, Location (Time Frame)
Menaker et al., J Trauma Acute Care Surg 2014 
Secondary Analysis of a Prospective Observational Study
Multicenter (May 2007 to January 2010)
Median age, 11.8 yrs; interquartile range (IQR) 6.3-15.5 yrs
Evaluated the variability of clinician-performed FAST examinations and the use of abdominal CT following FAST examination in children with blunt trauma
373 (5.8%) were diagnosed with intra-abdominal injury
3,015 (46.6%) underwent abdominal CT scanning. Only 887 (13.7%) underwent FAST examination before CT scan.
Use of the FAST increased as clinician suspicion for intra-abdominal injury increased. When clinicians had a lower suspicion, they were significantly less likely to order a CT scan, if a FAST examination was performed.
Holmes et al., JAMA 2017 
Randomized Clinical Trial
University of California, Davis Medical Center (April 2012-May 2015)
Mean 9.7 yrs; SD 5.3 yrs
Studied the impact of the FAST scan on on multiple patient centered outcomes
Hemodynamically stable patients with blunt torso trauma were randomized a FAST or no FAST scan.
50 had intra-abdominal injury, including 40 patients (80%) with intraperitoneal fluid and 9 patients underwent laparotomy.
No difference in the proportion obtaining CT, missed intra-abdominal injuries, length of stay, or cost.
Kornblith et al., Acad Emerg Med 2020 
University of California, Benioff Children’s Hospital Oakland (November 2013 to July 2015)
Median age 8 yr; IQR 4-12 yr
Query of trauma database for children who met institutional trauma activation criteria and who also had a FAST performed.
50 (14%) patients were found to have an intra-abdominal injury with 13 (4%) requiring intervention.
Positive FAST and positive physical exam were found to be independent predictors of intra-abdominal injury, both with a 74% sensitivity.
When combined, FAST and physical exam (FAST-enhanced physical exam) improved sensitivity to 88% (NPV 97.3%).
Liang et al., Pediatr. Emerg Care 2021 
Systematic Review and Meta-Analysis
Multicenter (January 1966- March 2018)
Based on 8 studies, the FAST had a pooled sensitivity of 35% and specificity 96% for intra-abdomianal injury.
All 8 studies were prospective; 1 of the 8 was the 2017 Holmes paper mentioned above .
Conclusion: For a positive FAST, the post-test probability of an intra-abdominal injury was 63% meaning that those patients should get a CT to characterize injury. If the FAST is negative, you may still need a CT, because the post-test probability of intra-abdominal injury was still relatively high at 9%.
None of the studies had low enough negative likelihood ratios to obviate the need for CT.
Although a negative FAST alone does not exclude an intra-abdominal injury, it can identify low-risk patients with a reassuring physical exam and GCS 14-15.
Kornblith et al., JAMA 2022 
Expert, consensus–based Modified Delphi
International multicenter (May 2021 to June 2021)
Generated definitions for complete pediatric FAST and E-FAST studies in the context of blunt trauma
The use of FAST in pediatric trauma is an evolving area of active research. A clear consensus on the way the FAST fits into pediatric trauma protocols is yet to be determined. Studies will need to be performed to examine the benefits of serial FAST, patient factors that may influence its test characteristics, and effect on patient centered outcomes.
There are a number of strategies to incorporate the above studies into clinical care, and one example is illustrated in the algorithm below. Keep in mind that FAST should be used in conjunction with other signs and symptoms of intra-abdominal injury (vomiting, decrease breath sounds, abdominal pain, thoracic wall trauma). Also consider laboratory testing such as liver function tests and urinalysis, depending on the clinical context and consulting your surgical colleagues.
The primary survey is completed with airway, breathing, and circulation noted to be intact. As someone starts the secondary survey, you grab a phased array probe and perform a FAST . You observe the following:
Pelvis View, Sagittal
Pelvis View, Transverse
You call out ‘FAST negative’ to the documenting nurse and team leader.
The patient has radiographs performed of his chest, pelvis, neck, and right forearm. He is diagnosed with a type 3 supracondylar humeral fracture but the other radiographs are negative for fracture and pneumothorax. The rest of his evaluation is reassuring. Orthopedics is consulted and they admit him for surgery. He is discharged home the next day with pediatrician follow up.
Pediatrician Clinic Follow-Up
At her pediatrician clinic visit 1 week later, he is playful and active with his arm in a cast. He has been eating and drinking normally without any complaints of abdominal pain. He has orthopedics follow up scheduled for the following week.
Kenefake ME, Swarm M, Walthall J. Nuances in Pediatric Trauma. Emerg Med Clin North Am. 2013;31(3):627-652. doi:10.1016/j.emc.2013.04.004
Melniker LA, Leibner E, McKenney MG, Lopez P, Briggs WM, Mancuso CA. Randomized controlled clinical trial of point-of-care, limited ultrasonography for trauma in the emergency department: the first sonography outcomes assessment program trial. Ann Emerg Med. 2006;48(3):227-235. doi:10.1016/j.annemergmed.2006.01.008
Brenkert TE, Adams C, Vieira RL, Rempell RG. Peritoneal fluid localization on FAST examination in the pediatric trauma patient. Am J Emerg Med. 2017;35(10):1497-1499. doi:10.1016/j.ajem.2017.04.025
Jehle DVK, Stiller G, Wagner D. Sensitivity in Detecting Free Intraperitoneal Fluid With the Pelvic Views of the FAST Exam.
Netherton S, Milenkovic V, Taylor M, Davis PJ. Diagnostic accuracy of eFAST in the trauma patient: a systematic review and meta-analysis. CJEM. 2019;21(6):727-738. doi:10.1017/cem.2019.381
Menaker J, Blumberg S, Wisner DH, et al. Use of the focused assessment with sonography for trauma (FAST) examination and its impact on abdominal computed tomography use in hemodynamically stable children with blunt torso trauma. J Trauma Acute Care Surg. 2014;77(3):427-432. doi:10.1097/TA.0000000000000296
Berona K, Kang T, Rose E. Pelvic Free Fluid in Asymptomatic Pediatric Blunt Abdominal Trauma Patients: A Case Series and Review of the Literature. J Emerg Med. 2016;50(5):753-758. doi:10.1016/j.jemermed.2016.01.003
Holmes JF, Gladman A, Chang CH. Performance of abdominal ultrasonography in pediatric blunt trauma patients: a meta-analysis. J Pediatr Surg. 2007;42(9):1588-1594. doi:10.1016/j.jpedsurg.2007.04.023
Liang T, Roseman E, Gao M, Sinert R. The Utility of the Focused Assessment With Sonography in Trauma Examination in Pediatric Blunt Abdominal Trauma: A Systematic Review and Meta-Analysis. Pediatr Emerg Care. 2021;37(2):108-118. doi:10.1097/PEC.0000000000001755
Holmes JF, Kelley KM, Wootton-Gorges SL, et al. Effect of Abdominal Ultrasound on Clinical Care, Outcomes, and Resource Use Among Children With Blunt Torso Trauma: A Randomized Clinical Trial. JAMA. 2017;317(22):2290-2296. doi:10.1001/jama.2017.6322
Kornblith AE, Graf J, Addo N, et al. The Utility of Focused Assessment With Sonography for Trauma Enhanced Physical Examination in Children With Blunt Torso Trauma. Acad Emerg Med Off J Soc Acad Emerg Med. 2020;27(9):866-875. doi:10.1111/acem.13959
Riera A, Hayward H, Torres Silva C, Chen L. Reevaluation of FAST Sensitivity in Pediatric Blunt Abdominal Trauma Patients: Should We Redefine the Qualitative Threshold for Significant Hemoperitoneum? Pediatr Emerg Care. 2021;37(12):e1012. doi:10.1097/PEC.0000000000001877
Kornblith AE, Addo N, Plasencia M, et al. Development of a Consensus-Based Definition of Focused Assessment With Sonography for Trauma in Children. JAMA Netw Open. 2022;5(3):e222922. Published 2022 Mar 1. doi:10.1001/jamanetworkopen.2022.2922
Problem: Central venous line (CVL) placement is a key skill for emergency medicine providers. Sites for central line placement include the internal jugular vein, subclavian vein, and femoral vein. Indications include, but are not limited to fluid resuscitation, medication administration, central venous pressure monitoring, pulmonary artery catheter introduction, and transvenous pacing wire placement. Procedural complications can include catheter-associated infection and arterial puncture. Success rates for CVL placement vary based on location and provider experience [1-3]. Point-of-Care Ultrasound (POCUS) increases both success rate and patient safety when used to guide CVL placement .
Figure 1. Setup for ultrasound-capable, 3D-printed central line trainer
The ultrasound-capable, 3D-printed central line trainer was created to facilitate realistic training of POCUS-guided CVL placement, specifically utilizing the internal jugular vein. The trainer uses a ballistic gel insert that is ultrasound-capable and replaceable, as needed.
The model can be utilized by anyone needing practice and training on central line placement. This includes medical and physician assistant students, residents, and fellows. It will be particularly useful with students familiar with POCUS basics.
In our experience, 4-5 students were able to utilize the model before the wear from repeated use began to impact the imaging and structure of the model, necessitating replacement of the insert. The dilation step of the Seldinger technique can be skipped or simulated in order to prolong the life of the gel insert.
The initial head model was designed using 2 common 3D modeling software systems: Tinkercad and Meshmixer
A generic head and neck model was imported into Meshmixer. Using the available tools in Meshmixer, the head was rotated to the side and the neck was manipulated to enhance the appearance of an extended neck with close attention to the sternocleidomastoid muscle and clavicle.
The model was then imported into Tinkercad and a section of the neck was removed, inverted, and manipulated inside of a box to create a negative (mold).
Figure 2. Screenshot of head being edited in Tinkercad software
Figure 3. Screenshot of neck mold being edited in Tinkercad software
The head was printed with Polylactic acid (PLA) filament in 2 sections that were then glued together with superglue. The seam was sealed and smoothed with latex caulk. The files for both the head and the mold can be found in this Google Drive folder.
A hole was drilled from the base of the neck through the top of the head. A second hole was drilled in the base of the model.
To make a suitable tray for the ballistic gel insert, a thin plate was printed and then cut to fit the shape of the neck. Finally, that piece was glued to the bottom of the model.
The model was painted using matte spray paint.
Figure 4. Use of matte spray paint to paint the model
The mold was printed next. Two holes were drilled on either side to allow for insertion of latex tubing.
The ballistic gel was heated according to the directions on the box. The gel can be colored using dye or acrylic paint. Caution should be practiced when using acrylic paint. The heated gel can foam up, increasing the possibility of injury from burn.
While the gel was heating, the mold was prepared. The bottom was coated with a thin layer of dish soap to assist with gel release. Two sections of latex tubing, approximately 2 feet each were inserted into the mold. Modeling clay was used to fill the gaps.
Once colored and thoroughly heated, the gel was poured into the mold.
Figure 5. Preparation of the mold in which the heated gel will be poured
Figure 6. The heated, colored gel is poured into the mold
After curing, the latex tubes were removed. The gel neck model was then removed and placed into the accompanying space on the 3d printed trainer.
The latex tubing was fished back through the available holes, and filled with water. As an optional step, a 30 cc syringe was attached to one end of the thicker tube. Tube stoppers can also be printed and used in place of hemostats. Pumping the syringe plunger simulates the appearance of arterial flow on ultrasound.
Video Demonstration of Final Product
We are currently investigating how best to research this model. The model is inexpensive compared to available commercial CVL trainers. We estimate the cost at approximately $80 per model in materials. This, of course, does not include the price of a 3d printer, 18v drill, or drill bit. Two comparable models available for purchase are both listed for over $1000 [5, 6]. The build time is approximately 1 week with time spent printing, glue-drying, and ballistic gel setting. The model can be used repeatedly and the insert remade many times over.
If another model were to be designed, the top of the head could be sacrificed in favor of an elongated neck section. The top of the head provides no value and consumes 3d printing filament. Furthermore, an elongated neck may be preferable for a new learner by allowing more room to practice probe and hand placement.
Theory behind the innovation
Simulation as a means of teaching has been a firmly established practice across the landscape of medical education. The model in question is high-fidelity and offers the user a realistic experience in a low-stress environment. The model is small enough to be portable and can be used with little preparation, making it an ideal tool for just-in-time training in the emergency department.
Tools that allow the learner to practice multiple steps of a skill during one exercise are invaluable for skill development, competency-based medical education and mastery learning.
Led by series editor, Dr. Mary Haas, the IDEA series showcases examples of what programs worldwide have been doing to make residency conference more entertaining, engaging, and most of all, educational for residents. Read more publications from the series.
McGee DC, Gould MK. Preventing complications of central venous catheterization. New England Journal of Medicine. 2003;348(12):1123-1133. doi:10.1056/nejmra011883
Schummer W, Köditz JA, Schelenz C, Reinhart K, Sakka SG. Pre-procedure ultrasound increases the success and safety of central venous catheterization. British Journal of Anaesthesia. 2014;113(1):122-129. doi:10.1093/bja/aeu049
E Portalatin M, Fakhoury E, Brancato R, et al. Factors contributing to unsuccessful central line placement in the neck and chest. Surgery: Current Trends and Innovations. 2019;3(2):1-5. doi:10.24966/scti-7284/100015