Figure 7B is used with permission from the collection of Dr. Abhilash Koratala.

All ultrasounds in this protocol were performed on human subjects and were conducted following the ethical standards of the University of Illinois Hospital and the Declaration of Helsinki and its revisions. The imaging was performed on the authors themselves and patients in the emergency department as part of routine education and clinical care with preceding verbal consent as is the standard for the institution. Images collected illustrate both normal anatomy and physiology as well as abnormal findings collected at the University of Illinois Hospital. Images used to illustrate scanning techniques were performed on members of the writing team. All ultrasound images are free of any identifying information. The subsequent protocol was designed using sources from peer-reviewed journals and book chapters10,15,16,17,18,19. For this review, the protocol will focus on obtaining US images of adults.
1. Safety
NOTE: POCUS studies can be performed with non-sterile gloves, either nitrile or latex, depending on patient allergies. Additional safety measures may be taken based on clinical context and institutional policies.
<ol>
	<li>Examine the ultrasound system for cleanliness prior to use and clean the machine and probes in the appropriate manner after use. The cleaning material and process are dictated by the ultrasound unit manufacturer and institutional standards.</li>
</ol>
2. Selection of probe
<ol>
	<li>For most adults, the abdominal aorta is best visualized with a 2.5-3.5 MHz curvilinear probe, which has a large footprint and a wide field of view with a convex beam shape. This probe will generally provide excellent resolution and measurement capabilities.</li>
	<li>Alternatively, use the phased array probe (1-5 mHz), typically used for echocardiography and often informally referred to as the cardiac probe. 
	&#8203;NOTE: The phased array probe can be useful especially when attempting to visualize the proximal abdominal aorta as it exits through the diaphragmatic hiatus. This is especially true if the space just inferior to the xyphoid process is too narrow to accommodate the wider curvilinear probe. The phased array probe has a rectangular footprint and a triangular beam shape with a narrower field of view than the curvilinear probe but should be adequate to achieve the imaging goals.</li>
</ol>
3. Machine presets
<ol>
	<li>Use the abdominal preset on the machine regardless of the probe used.</li>
	<li>Set the mode to B mode or 2-dimensional grayscale.</li>
	<li>Set the depth to 20 cm. 
	NOTE: This is typically adequate to visualize the vertebral body which is an important landmark for the aorta.</li>
	<li>Adjust the depth once the aorta is visualized to keep the aorta in the midfield of the screen.</li>
	<li>Consider using harmonic imaging to provide better visualization if imaging is challenging due to excessive bowel gas. 
	NOTE: Harmonics uses the resonance characteristics of tissue and creates a higher-resolution image with fewer artifacts.</li>
	<li>Choose a lower frequency range for patients with a high body mass index to improve image acquisition.</li>
</ol>
4. Scanning technique
<ol>
	<li>Apply ultrasound gel to the transducer.</li>
	<li>Position the patient supine with the abdomen exposed. Hip flexion, if tolerated by the patient, will relax the abdominal muscles and may improve image acquisition. 
	NOTE: Bowel gas can impede image acquisition. To improve image acquisition in the presence of bowel gas, the operator can apply firm, continuous pressure, known as graded compression, to the scanning area for a few minutes, displacing the bowel gas. Evaluation of the aorta in the coronal plane can also avoid bowel gas encountered in the transverse plane (see step 4.3.5).</li>
	<li>For a thorough evaluation of the abdominal aorta, obtain the images listed below.
	<ol>
		<li>Obtain images of the proximal aorta in the transverse plane.
		<ol>
			<li>Orient the transducer in the transverse plane with the indicator toward the patient&#39;s right. Ensure that the indicator position matches the indicator on the screen (Figure 1A).</li>
			<li>Place the transducer just distal to the patient&#39;s xiphoid process and apply light pressure to visualize the anterior aspect of the vertebra with its hyperechoic shadow-casting arch (Figure 1B). 
			NOTE: The liver will appear in the upper left corner of the screen and acts as an acoustic window. The aorta will appear just above the vertebral body as an anechoic circle on the right side of the screen, corresponding to the patient&#39;s left. The inferior vena cava (IVC) is on the left side of the screen, corresponding to the patient&#39;s right. The IVC has a thinner wall than the aorta and is often collapsible even with light pressure.</li>
			<li>Slide the transducer caudally until the celiac trunk is visualized. The celiac trunk is short and quickly bifurcates into the hepatic artery and splenic artery. When the two arteries are visualized together, this is called the seagull sign (Figure 2).</li>
			<li>Capture these images for later review by clicking the button on the system that records clips.</li>
			<li>Slide the transducer caudally to encounter the superior mesenteric artery (SMA), which comes off the anterior aorta and very quickly courses inferiorly, typically following a parallel path with the aorta. The splenic vein courses anterior to the SMA and the left renal vein courses between the SMA and the aorta (Figure 3).</li>
			<li>Capture these images for later review by clicking the button on the system that records clips.</li>
			<li>Measure the AP diameter of the suprarenal aorta by optimizing a live image of the aorta in this location and then pressing the system&#39;s freeze button.</li>
			<li>Press caliper or measure and move the track ball or touchpad of the system to the outer edge of the anterior wall, the adventitia, and click select.</li>
			<li>Move the trackball or touchpad again to the outer edge of the posterior wall and click Select. Wait for the system to generate a measurement (Figure 4).</li>
			<li>Save this image as a still image containing the measurement by clicking the button on the system that saves still images . 
			NOTE: The upper limit of normal of the AP diameter of the aorta is 3.0 cm. Any measurement &#62;3 cm is considered aneurysmal15,16,20,21.</li>
		</ol>
		</li>
		<li>Image the distal aorta in the transverse plane. 
		NOTE: The distal aorta comprises two-thirds of the abdominal aorta and begins just distal of the renal arteries. The majority of AAAs occur in this distal segment.
		<ol>
			<li>As with the proximal aorta, continue scanning in a transverse plane visualizing the entirety of the aorta through the bifurcation.</li>
			<li>Capture these images for later review by clicking the button on the system that records clips.</li>
			<li>When a live image of the distal aorta is optimized, measure the AP diameter of the infrarenal aorta.</li>
			<li>Press caliper or measure and move the trackball or touchpad of the system to the outer edge of the anterior wall, the adventitia, and click select.</li>
			<li>Move the trackball or touchpad again to the outer edge of the posterior wall and click Select. Wait for the system to generate a measurement.</li>
			<li>Save this image as a still image containing the measurement by clicking the button on the system that saves still images. 
			NOTE: It is prudent to obtain at least two measurements of the distal aorta given its greater length and increased likelihood of having aneurysmal dilations.</li>
			<li>Adjust the depth as the abdominal aorta courses caudally through the abdomen, since it becomes more superficial and tapers slightly.</li>
		</ol>
		</li>
		<li>Obtain a video clip of the aortic bifurcation into the left and right iliac arteries (Video 1-see Supplemental File 1: Supplemental Figure S1).
		<ol>
			<li>Continue scanning caudally, adjusting the depth as necessary to maintain the aorta and vertebral body in the middle of the screen.</li>
			<li>Scan through the aortic bifurcation into the left and right iliac arteries.</li>
			<li>Capture images while scanning through the bifurcation.</li>
		</ol>
		</li>
		<li>Obtain images and video clips of the aorta in the longitudinal plane.
		<ol>
			<li>Place the probe in the proximal abdomen, starting again in the subxiphoid area.</li>
			<li>It is often easier to begin in the transverse plane with the indicator toward the patient&#39;s right. Once the transverse view of the aorta is optimized, rotate the probe clockwise, following the aorta as the image becomes longitudinal on the screen and the indicator is pointing toward the patient&#39;s head (Figure 5A).</li>
			<li>Acquire images while scanning caudally examining for aneurysmal dilatations.</li>
			<li>Capture these images for later review by clicking the button on the system that records clips. 
			NOTE: The celiac trunk and SMA are easily visible projecting from the anterior aorta in long axis view (Figure 5B). It is advisable NOT to measure the diameter of the aorta in the longitudinal axis. If the US beam intersects the aorta tangentially, as opposed to in its midline, the measurement will be falsely smaller than if it were through the maximal AP diameter (Figure 6).</li>
		</ol>
		</li>
		<li>Optional: Obtain a longitudinal view of the aorta in the coronal plane. This view is useful if obtaining views in the transverse or longitudinal planes is difficult.
		<ol>
			<li>Begin with the transducer in the coronal plane at the midaxillary line on the patient&#39;s right with the indicator pointing cranially (Figure 7A).</li>
			<li>If the patient is able, position them in the left lateral decubitus position for better image acquisition.</li>
			<li>Scan the aorta in a coronal plane. The aorta will be visualized deep to the IVC if both vessels are imaged (Figure 7B).</li>
			<li>Capture these images for later review by clicking the button on the system that records clips.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

Imaging the Abdominal Aorta with Point-of-Care Ultrasound

<ol>
	<li>Hashim, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+utility+of+point+of+care+ultrasonography+(POCUS).">The utility of point of care ultrasonography (POCUS).</a> Annals of Medicine and Surgery. 71, 102982 (2021).</li><li>Ramgobin, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=POCUS+in+internal+medicine+curriculum:+quest+for+the+Holy+Grail+of+modern+medicine.">POCUS in internal medicine curriculum: quest for the Holy Grail of modern medicine.</a> Journal of Community Hospital Internal Medicine. 12 (5), 36-42 (2012).</li><li>Anjum, A., von Allmen, R., Greenhalgh, R., Powell, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Explaining+the+decrease+in+mortality+from+abdominal+aortic+aneurysm+rupture.">Explaining the decrease in mortality from abdominal aortic aneurysm rupture.</a> The British Journal of Surgery. 99 (5), 637-645 (2012).</li><li>Reimerink, J., van der Laan, M. J., Koelemay, M. J., Balm, R., Legemate, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+review+and+meta-analysis+of+population-based+mortality+from+ruptured+abdominal+aortic+aneurysm.">Systematic review and meta-analysis of population-based mortality from ruptured abdominal aortic aneurysm.</a> The British Journal of Surgery. 100 (11), 1405-1413 (2013).</li><li>DeMartino, R. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Population-based+assessment+of+the+incidence+of+aortic+dissection,+intramural+hematoma,+and+penetrating+ulcer,+and+its+associated+mortality+from+1995+to+2015.">Population-based assessment of the incidence of aortic dissection, intramural hematoma, and penetrating ulcer, and its associated mortality from 1995 to 2015.</a> Circulation: Cardiovascular Quality and Outcomes. 11 (8), e004689 (2018).</li><li>Ivosic, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+isolated+dissection+of+the+abdominal+aorta.">Spontaneous isolated dissection of the abdominal aorta.</a> Collegium Antropologicum. 37 (4), 1361-1363 (2013).</li><li>M&#243;zes, G., Gloviczki, P., Park, W. M., Schultz, H. L., Andrews, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+dissection+of+the+infrarenal+abdominal+aorta.">Spontaneous dissection of the infrarenal abdominal aorta.</a> Seminars in Vascular Surgery. 15 (2), 128-136 (2002).</li><li>Tang, E. L., Chong, C. S., Narayanan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolated+abdominal+aortic+dissection.">Isolated abdominal aortic dissection.</a> British Medical Journal Case Reports. 2014, bcr2013203097 (2014).</li><li>Farber, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spontaneous+infrarenal+abdominal+aortic+dissection+presenting+as+claudication:+case+report+and+review+of+the+literature.">Spontaneous infrarenal abdominal aortic dissection presenting as claudication: case report and review of the literature.</a> Annals of Vascular Surgery. 18 (1), 4-10 (2004).</li><li>Reardon, R., Clinton, M., Young, J., Nogueira, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aortic+emergencies.">Aortic emergencies.</a> Ma and Mateer's Emergency Ultrasound. , 235-252 (2021).</li><li>Gibbons, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Point-of-care+ultrasound+for+the+detection+of+aortic+dissections+in+the+emergency+department.">Point-of-care ultrasound for the detection of aortic dissections in the emergency department.</a> Annals of Emergency Medicine. 70 (4), S143 (2017).</li><li>Rubano, E., Mehta, N., Caputo, W., Paladino, L., Sinert, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+review:+emergency+department+bedside+ultrasonography+for+diagnosing+suspected+abdominal+aortic+aneurysm.">Systematic review: emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm.</a> Academic Emergency Medicine. 20 (2), 128-138 (2013).</li><li>Earl-Royal, E., Nguyen, P. D., Alvarez, A., Gharahbaghian, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+type+B+aortic+dissection+in+the+emergency+department+with+point-of-care+ultrasound.">Detection of type B aortic dissection in the emergency department with point-of-care ultrasound.</a> Clinical Practice and Cases in Emergency Medicine. 3 (3), 202-207 (2019).</li><li>Fojtik, J. P., Costantino, T. G., Dean, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+diagnosis+of+aortic+dissection+by+emergency+medicine+ultrasound.">The diagnosis of aortic dissection by emergency medicine ultrasound.</a> Journal of Emergency Medicine. 32 (2), 191-196 (2007).</li><li>Fadel, B. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound+imaging+of+the+abdominal+aorta:+a+comprehensive+review.">Ultrasound imaging of the abdominal aorta: a comprehensive review.</a> Journal of the American Society of Echocardiography. 34 (11), 1119-1136 (2021).</li><li>Dean, A., Cosby, K. S., Kendall, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Practical guide to emergency ultrasound. , (2014).</li><li>Erbel, R., Aboyans, V., Boileau, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2014+ESC+Guidelines+on+the+diagnosis+and+treatment+of+aortic+diseases:+Document+covering+acute+and+chronic+aortic+diseases+of+the+thoracic+and+abdominal+aorta+of+the+adult.+The+Task+Force+for+the+Diagnosis+and+Treatment+of+Aortic+Diseases+of+the+European+Society+of+Cardiology+(ESC).">2014 ESC Guidelines on the diagnosis and treatment of aortic diseases: Document covering acute and chronic aortic diseases of the thoracic and abdominal aorta of the adult. The Task Force for the Diagnosis and Treatment of Aortic Diseases of the European Society of Cardiology (ESC).</a> European Heart Journal. 35 (41), 2873-2926 (2014).</li><li>G&#252;rtelschmid, M., Bj&#246;rck, M., Wanhainen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+three+ultrasound+methods+of+measuring+the+diameter+of+the+abdominal+aorta.">Comparison of three ultrasound methods of measuring the diameter of the abdominal aorta.</a> The British Journal of Surgery. 101 (6), 633-636 (2014).</li><li>Barkin, A., Rosen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound+detection+of+abdominal+aortic+aneurysm.">Ultrasound detection of abdominal aortic aneurysm.</a> Emergency Medicine Clinics of North America. 22 (3), 675-682 (2004).</li><li>Jaakkola, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interobserver+variability+in+measuring+the+dimensions+of+the+abdominal+aorta:+comparison+of+ultrasound+and+computed+tomography.">Interobserver variability in measuring the dimensions of the abdominal aorta: comparison of ultrasound and computed tomography.</a> European Journal of Vascular and Endovascular Surgery. 12 (2), 230-237 (1996).</li><li>Costantino, T. G., Bruno, E. C., Handly, N., Dean, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accuracy+of+emergency+medicine+ultrasound+in+the+evaluation+of+abdominal+aortic+aneurysm.">Accuracy of emergency medicine ultrasound in the evaluation of abdominal aortic aneurysm.</a> Journal of Emergency Medicine. 29 (4), 455-460 (2005).</li><li>Reed, K. C., Curtis, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aortic+emergencies+Part+II:+abdominal+aneurysms+and+aortic+trauma.">Aortic emergencies Part II: abdominal aneurysms and aortic trauma.</a> Emergency Medicine Practice. 8 (3), 1-24 (2006).</li><li>American College of Emergency Physicians. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Ultrasound guidelines: emergency, point-of-care, and clinical ultrasound guidelines in medicine. , (2023).</li><li>Kent, K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+practice.+Abdominal+aortic+aneurysms.">Clinical practice. Abdominal aortic aneurysms.</a> New England Journal of Medicine. 371 (22), 2101-2108 (2014).</li><li>Dobrocky, T., Stranzinger, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pseudothrombus+of+the+aorta:+a+common+mirror+artifact+in+pediatric+patients.">Pseudothrombus of the aorta: a common mirror artifact in pediatric patients.</a> Journal of Diagnostic Medical Sonography. 29 (5), 195-198 (2013).</li><li>Hadzik, R., Bombi&#324;ski, P., Brzewski, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Double+aorta+artifact+in+sonography+-+a+diagnostic+challenge.">Double aorta artifact in sonography - a diagnostic challenge.</a> Journal of Ultrasound. 17 (68), 36-40 (2017).</li><li>Plummer, D., Clinton, J., Matthew, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emergency+department+ultrasound+improves+time+to+diagnosis+and+survival+in+ruptured+abdominal+aortic+aneurysm+[abstract].">Emergency department ultrasound improves time to diagnosis and survival in ruptured abdominal aortic aneurysm [abstract].</a> Academic Emergency Medicine. 5 (5), 417 (1998).</li><li>Tayal, V. S., Graf, C. D., Gibbs, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospective+study+of+accuracy+and+outcome+of+emergency+ultrasound+for+abdominal+aortic+aneurysm+over+two+years.">Prospective study of accuracy and outcome of emergency ultrasound for abdominal aortic aneurysm over two years.</a> Academic Emergency Medicine. 10 (8), 867-871 (2003).</li><li>Kuhn, M., Bonnin, R. L., Davey, M. J., Rowland, J. L., Langlois, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emergency+department+ultrasound+scanning+for+abdominal+aortic+aneurysm:+accessible,+accurate,+and+advantageous.">Emergency department ultrasound scanning for abdominal aortic aneurysm: accessible, accurate, and advantageous.</a> Annals of Emergency Medicine. 36 (3), 219-223 (2000).</li><li>Cazes, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Emergency+ultrasound:+a+prospective+study+on+sufficient+adequate+training+for+military+doctors.">Emergency ultrasound: a prospective study on sufficient adequate training for military doctors.</a> Diagnostic and Interventional Imaging. 94 (11), 1109-1115 (2013).</li><li>Bonnafy, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliability+of+the+measurement+of+the+abdominal+aortic+diameter+by+novice+operators+using+a+pocket-sized+ultrasound+system.">Reliability of the measurement of the abdominal aortic diameter by novice operators using a pocket-sized ultrasound system.</a> Archives of Cardiovascular Diseases. 106 (12), 644-650 (2013).</li><li>Baliga, R. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+imaging+in+aortic+dissection+and+related+syndromes.">The role of imaging in aortic dissection and related syndromes.</a> Journal of the American College of Cardiology: Cardiovascular Imaging. 7 (4), 406-424 (2014).</li><li>Lewiss, R. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CORD-AEUS:+consensus+document+for+the+emergency+ultrasound+milestone+project.">CORD-AEUS: consensus document for the emergency ultrasound milestone project.</a> Academic Emergency Medicine. 20 (7), 740-745 (2013).</li></ol>

The authors have no conflicts of interest to declare.

Timely diagnosis of AAA and aortic dissection is key in the treatment of these high-morbidity conditions. POCUS used in the diagnosis of AAA leads to improved outcomes and significantly decreases the time to diagnosis and operative intervention when compared with traditional imaging27. POCUS has high sensitivity and specificity for AAA and high specificity for aortic dissection12,13,19,<sup cla...

Point-of-care ultrasound (POCUS) has increased in use over the last several years and is being increasingly incorporated into various residency training programs1,2. POCUS has great utility in critical care areas such as the emergency department and the intensive care unit, specifically to aid in the rapid diagnosis of life-threatening intraabdominal emergencies such as acute aortic dissection, as well as abdominal aortic aneurysms, especially those at risk for rupture and those that have ruptured into the peritoneum.
AAA rupture and acute aortic dissection are associated with high mortality. The mortality of ruptured aortic aneurysms ranges from 67% to 94%3,4. The mortality associated with type A aortic dissection increases at a rate of 1% per hour after acute dissection and the mortality of type B aortic dissection ranges from 10% to 25% at 30 days5. Abdominal aortic dissection in isolation is rare and accounts for only 0.2% to 4% of all aortic dissections6,7,8,9,10. Since most abdominal aortic dissections occur as an extension of thoracic aortic dissections, evaluation of the abdominal aorta for evidence of dissection may aid in the diagnosis of thoracic aortic dissection11.
Computed tomography with angiography (CTA) is the gold standard for imaging pathology associated with the abdominal aorta; however, it has several drawbacks. It may be time-consuming, especially in an unstable patient, and requires a technician to perform and a radiologist or vascular surgeon to interpret the images. CTA uses ionizing radiation and requires the use of intravenous contrast dye for optimal detection of pathology. Furthermore, the performance of CTA requires potentially unstable patients to leave the critical care area. In contrast, POCUS is non-invasive, cost-effective, and lacks the ionizing radiation and contrast dye that CT requires. It can also be performed and interpreted by the same individual in real time and does not require the patient to leave the monitored area.
A systematic review of emergency department POCUS for diagnosing AAA by Rubano et al. revealed a sensitivity of 99% and specificity of 98%, with a positive likelihood ratio of 99 and a negative likelihood ratio of 0.0112. This pooled analysis evaluated the test characteristics over a varied group of operators, including resident and attending physicians with a wide range of training in POCUS.
The test characteristics for the POCUS evaluation of abdominal aortic dissection are different from those of AAA and may vary depending on the origin of the dissection. Sonographic findings of an intimal flap separating the true and false lumens have a sensitivity of 67%-79% and a specificity of 99%-100% for aortic dissection13,14. As most aortic dissections found in the abdomen are an extension of a thoracic aortic dissection, additional POCUS applications of the heart and lungs to evaluate for pericardial effusion, aortic root dilatation, and left pleural effusion may be performed, but will not be the focus of this paper13.
Finally, it is important to note that the United States Preventative Services task force provides a Grade B recommendation for a one-time ultrasound screening for AAA in men aged 65-75 who have ever smoked. This is particularly relevant to the primary care setting.
This review will describe a step-by-step protocol for the performance of POCUS in the bedside evaluation of the abdominal aorta, specifically to evaluate for AAA and abdominal aortic dissection. This protocol assumes a basic knowledge of diagnostic ultrasound, including physics, instrumentation, as well as medical knowledge of anatomy and pathologic states of the abdominal aorta and major branching arteries. Readers are advised to refer to other sources for prerequisite knowledge.

<table><tbody><tr><td>M9 Ultrasound Machine&amp;nbsp;</td><td>Mindray&amp;nbsp;</td><td>n/a</td><td>Used to obtain all adequate and inadequate images/clips</td></tr></tbody></table>

an approach to point-of-care ultrasound evaluation of the abdominal aorta

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography (CT) is the current gold standard to image the abdominal aorta, the process of obtaining a CT may be time-consuming, requires the use of intravenous contrast dye, and involves exposure to ionizing radiation. Point-of-care Ultrasound (POCUS) can be performed at the bedside and has excellent sensitivity and specificity for the diagnosis of abdominal aortic aneurysm and excellent specificity for the diagnosis of abdominal aortic dissection. Additionally, POCUS is non-invasive, cost-effective, lacks ionizing radiation, requires no intravenous contrast dye, and can be performed without taking the patient from a critical care area. Screening for abdominal aortic aneurysm (AAA) can be done in primary care settings as well. 
This article will review the approach to POCUS of the abdominal aorta to evaluate such critical pathology. In this paper, we will review the sonographic anatomy of the abdominal aorta as well as the choice of the ultrasound probe, description of POCUS image acquisition, and some pearls and pitfalls of using POCUS to aid in the diagnosis of potentially life-threatening abdominal aortic pathology.

Adequate exam 
One of the biggest challenges in obtaining accurate results from an abdominal aortic ultrasound is the lack of consensus about measurement. As noted in protocol step 4.3.1.10, any diameter of the abdominal aorta greater than 3 cm is considered aneurysmal15,16,22,23. There is, however, great variation in the methods used to measure the aorta's diameter, and no ...

Watch this Scientific Journal Video about An Approach to Point-Of-Care Ultrasound Evaluation of the Abdominal Aorta at JoVE.com

Author Spotlight: Using Point-of-Care Ultrasound for Comprehensive Evaluation of the Abdominal Aorta

This protocol reviews the steps to image the abdominal aorta with point-of-care ultrasound. We discuss image acquisition, troubleshooting imaging pitfalls and artifacts, and the recognition of life-threatening abdominal aortic pathology.

An Approach to Point-Of-Care Ultrasound Evaluation of the Abdominal Aorta

Disorders of the abdominal aorta, including aneurysms and dissection, have potentially high rates of morbidity and mortality. While computed tomography ...

an-approach-to-point-care-ultrasound-evaluation-abdominal

Research

JoVE Journal

Medicine

2.2K Views.  University of Illinois Hospital. We proberen het gebruik van point-of-care echografie of POCUS aan te tonen om de anatomie en pathologie van de abdominale aorta te evalueren. POCUS heeft een uitstekende sensitiviteit en specificiteit voor de evaluatie van abdominaal aorta-aneurysma en een uitstekende specificiteit voor de evaluatie van abdominale aortadissectie. Enkele van de uitdagingen zijn ervoor te zorgen dat POCUS-gebruikers voldoende training krijgen en ervoor te zorgen dat ze pathologie en artefacten nauwkeurig kunnen...

Video: Auteur in de schijnwerpers: point-of-care-echografie gebruiken voor uitgebreide evaluatie van de abdominale aorta

Balloon-based Injury to Induce Myointimal Hyperplasia in the Mouse Abdominal Aorta

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine balloon denudation model, which is comparable with established vessel injury models in large animals. The aorta denudation model with balloon catheters mimics the clinical setting and leads to comparable pathobiological and physiological changes. Briefly, after performing a horizontal incision in the aorta abdominalis, a balloon catheter will be inserted into the vessel, inflated, and introduced retrogradely. Inflation of the balloon will lead to intima injury and overdistension of the vessel. After removing the catheter, the aortic incision will be closed with single stiches. The model shown in this article is reproducible, easy to perform, and can be established quickly and reliably. It is especially suitable for evaluating expensive experimental therapeutic agents, which can be applied in an economical fashion. By using different knockout-mouse strains, the impact of different genes on MH development can be assessed.

This article demonstrates a murine model to study the development of myointimal hyperplasia (MH) after aortic balloon injury.

The use of animal models is essential for a better understanding of MH, one major cause for arterial stenosis.In this article, we demonstrate a murine ...

Measurement of Pulse Propagation Velocity, Distensibility and Strain in an Abdominal Aortic Aneurysm Mouse Model

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the abdominal aorta that exceeds the maximal intraluminal diameter (MILD) by 1.5 times of its original size. Clinical and experimental studies have shown that small aneurysms may rupture, while a subpopulation of large aneurysms may remain stable. Thus, in addition to the measurement of intraluminal diameter of the aorta, knowledge of structural traits of the vessel wall may provide important information to assess the stability of the AAA. Aortic stiffening has recently emerged as a reliable tool to determine early changes in the vascular wall. Pulse propagation velocity (PPV) along with the distensibility and radial strain are highly useful ultrasound-based methods relevant for assessing aortic stiffness. The primary purpose of this protocol is to provide a comprehensive technique for the use of ultrasound imaging system to acquire images and analyze the structural and functional properties of the aorta as determined by MILD, PPV, distensibility and radial strain.

This manuscript describes a detailed protocol for using high frequency ultrasound imaging to measure luminal diameter, pulse propagation velocity, distensibility and radial strain on a mouse model of abdominal aortic aneurysm.

An abdominal aortic aneurysm (AAA) is defined as a localized dilation of the abdominal aorta that exceeds the maximal intraluminal diameter (MILD) by 1.5 ...

Immunology and Infection

Protocol and Guidelines for Point-of-Care Lung Ultrasound in Diagnosing Neonatal Pulmonary Diseases Based on International Expert Consensus

Ultrasound is a safe bedside imaging tool that obviates the use of ionizing radiation diagnostic procedures. Due to its convenience, the lung ultrasound has received increasing attention from neonatal physicians. Nevertheless, clear reference standards and guideline limits are needed for accurate application of this diagnostic modality. This document aims to summarize expert opinions and to provide precise guidance to help facilitate the use of the lung ultrasound in the diagnosis of neonatal lung diseases.

Lung ultrasound is a noninvasive and valuable tool for bedside evaluation of neonatal lung diseases. However, a relative lack of reference standards, protocols and guidelines may limit its application. Here, we aim to develop a standardized neonatal lung ultrasound diagnostic protocol to be used in clinical decision-making.

Ultrasound is a safe bedside imaging tool that obviates the use of ionizing radiation diagnostic procedures. Due to its convenience, the lung ultrasound ...

Ultrasound Imaging of the Thoracic and Abdominal Aorta in Mice to Determine Aneurysm Dimensions

Contemporary high-resolution ultrasound instruments have sufficient resolution to facilitate the measurement of mouse aortas. These instruments have been widely used to measure aortic dimensions in mouse models of aortic aneurysms. Aortic aneurysms are defined as permanent dilations of the aorta, which occur most frequently in the ascending and abdominal regions. Sequential measurements of aortic dimensions by ultrasound are the principal approach for assessing the development and progression of aortic aneurysms in vivo. Although many reported studies used ultrasound imaging to measure aortic diameters as a primary endpoint, there are confounding factors, such as probe position and cardiac cycle, that may impact the accuracy of data acquisition, analysis, and interpretation. The purpose of this protocol is to provide a practical guide on the use of ultrasound to measure the aortic diameter in a reliable and reproducible manner. This protocol introduces the preparation of mice and instruments, the acquisition of appropriate ultrasound images, and data analysis.

Ultrasound imaging has become a common modality to determine the luminal dimensions of thoracic and abdominal aortic aneurysms in mice. This protocol describes the procedure to acquire reliable and reproducible two-dimensional ultrasound images of the ascending and abdominal aorta in mice.

Contemporary high-resolution ultrasound instruments have sufficient resolution to facilitate the measurement of mouse aortas. These instruments have been ...

Evaluation of a Point-of-Care Testing Analyzer for Measuring Peripheral Blood Leukocytes

White blood cell (WBC) is an important indicator of inflammation in the body, and it can help distinguish between bacterial and viral infections. At present, most primary medical institutions in China have a poor percentage of adoption of blood-testing technology, and a hematology detection system with a high price to performance ratio and easy operation is urgently needed in primary healthcare centers. This paper introduces the principle and operation procedures of a point-of-care testing (POCT) card-based leukocyte analyzer (evaluated system), which was used to detect WBC indexes such as neutrophils, lymphocytes, and intermediate group cells (including eosinophils, basophils, and monocytes) in whole blood. The results from the evaluated system were compared to those from two commercial automatic hematology analyzers (reference system). The correlation and consistency between the evaluated system and the commercial reference systems were analyzed. The results showed that WBC count and number of granulocytes detected by the evaluated and reference systems showed a strong positive correlation (rs = 0.972 and 0.973, respectively), while the number of lymphocytes showed a relatively low correlation (rs = 0.851). A Bland-Altman plot showed that the major difference between the values detected by the evaluated system and the reference systems is within 95% limits of agreement (LoA), indicating that the two systems are in good agreement. In conclusion, the evaluated system has an excellent correlation, robust consistency, and a reliable comparison with the results of the widely used automatic hematology analyzers. It is ideal for WBC detection in primary medical institutions where a full-automatic five-category hematology analyzer is unavailable, especially during the COVID-19 normalized prevention and control period.

A protocol to measure peripheral blood leukocytes using a POCT card-based leukocyte analyzer is presented here. Same blood samples were tested by two automated hematology analyzers to evaluate the consistency and accuracy of the results. The results showed that the evaluated analyzer had a good correlation with the reference system.

White blood cell (WBC) is an important indicator of inflammation in the body, and it can help distinguish between bacterial and viral infections. At ...

Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening sequelae. While whole leg compression ultrasound with color and spectral Doppler is commonly performed in radiology and vascular labs, point-of-care ultrasound (POCUS) is becoming more common in the acute care setting. Providers appropriately trained in focused POCUS can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. This paper describes a simplified yet validated approach to POCUS by describing a three-zone protocol for lower extremity DVT POCUS image acquisition. The protocol explains the steps in obtaining vascular images at six compression points in the lower extremity. Beginning at the level of the proximal thigh and moving distally to the popliteal space, the protocol guides the user through each of the compression points in a stepwise manner: from the common femoral vein to the femoral and deep femoral vein bifurcation, and, finally, to the popliteal vein. Further, a visual aid is provided that may assist providers during real-time image acquisition. The goal in presenting this protocol is to help make proximal lower extremity DVT exams more accessible and efficient for POCUS users at the patient&#39;s bedside.

Traditionally, lower extremity deep venous thrombosis (DVT) is diagnosed by radiology-performed venous duplex ultrasound. Providers appropriately trained in focused point-of-care ultrasound (POCUS) can perform a rapid bedside examination with high sensitivity and specificity in critically ill patients. We describe the scanning technique for focused POCUS DVT lower extremity examination.

Acute lower extremity deep venous thrombosis (DVT) is a serious vascular disorder that requires accurate and early diagnosis to prevent life-threatening ...

Point-of-Care Ultrasound: A Review of Ultrasound Parameters for Predicting Difficult Airways

Airway management remains a crucial part of perioperative care. The conventional approach to assessing potentially difficult airways emphasizes the LEMON method, which looks for and evaluates the Mallampati classification, signs of obstruction, and neck mobility. Clinical findings help predict a higher likelihood of difficult tracheal intubation, but no clinical result reliably excludes difficult intubation. Ultrasound as an adjunct to clinical examination can provide the clinician with a dynamic anatomical airway assessment, which is impossible with clinical examination alone. In the hands of anesthesiologists, ultrasound is becoming more popular in the perioperative period. This method is particularly applicable for identifying proper endotracheal tube positioning in specific patient populations, such as those who are morbidly obese and patients with head and neck cancer or trauma. The focus is on identifying the normal anatomy, correctly positioning the endotracheal tube, and refining the parameters that predict difficult intubation. Several ultrasound measurements are clinical indicators of difficult direct laryngoscopy in the literature. A meta-analysis revealed that the distance from the skin to the epiglottis (DSE) is most associated with a difficult laryngoscopy. An ultrasound of the airway could be applied in routine practice as an adjunct to the clinical examination. A full stomach, rapid sequence intubation, gross visual anatomical abnormalities, and restricted neck flexibility prevent using ultrasound to assess the airway. The airway evaluation is performed with a linear array transducer of 12-4 MHz, with the patient in the supine position, with no pillow, and with the head and neck in a neutral position. The central axis of the neck is where the ultrasound parameters are measured. These image acquisitions guide the standard ultrasound examination of the airway.

A point-of-care ultrasound (POCUS) is a simple, non-invasive, and portable tool that enables dynamic airway assessment. Several studies have attempted to determine the role of ultrasound parameters as an adjunct to clinical examination in predicting difficult laryngoscopies.

Airway management remains a crucial part of perioperative care. The conventional approach to assessing potentially difficult airways emphasizes the LEMON ...

Ultrasound Assessment of Aortic and Carotid Artery Intima-media Thickness in Children and Adolescents

Carotid intima-media thickness (IMT), measured using high-resolution B-mode ultrasonography, is a widely utilized surrogate marker of subclinical atherosclerosis, the pathophysiological process underlying most clinical cardiovascular disease events. Atherosclerosis is a gradual disease that originates early in life, thus, there has been increased interest in measuring carotid IMT in childhood and adolescence to assess structural change in the arterial vasculature in response to adverse exposures. However, the timing of atherosclerosis varies across the vascular tree. Primordial atherosclerotic lesions are present in the abdominal aorta as early as infancy, compared to mid-adolescence for the common carotid. Measurement of IMT at either site is susceptible to several technical challenges that need to be considered, especially in younger children. In this paper, we provide a detailed stepwise method for high-quality assessment of IMT of the abdominal aorta and common carotid artery in the young. We also provide insight into the appropriateness of either site when exploring the associations between early-life exposures and later-life cardiovascular disease.

The present article describes the methodological considerations for the noninvasive assessment of abdominal aortic and carotid intima-media thickness using B-mode ultrasonography. This technique is commonly used in the developmental origins of health and disease research as a surrogate for early arterial changes.

Carotid intima-media thickness (IMT), measured using high-resolution B-mode ultrasonography, is a widely utilized surrogate marker of subclinical ...

Using Point of Care Ultrasound to Augment Acquisition of Physical Exam Skills: Veins and Arteries

Source: Joseph H. Donroe, Rachel Liu; Yale School of Medicine, USA
Vascular diseases make up most cases of emergency hospitalization and carry a high mortality risk. Point-of-care ultrasound or POCUS enables accurate diagnosis of these diseases and shortens the time between detection of the cause and selection of appropriate treatment strategies, thus, reducing the patient mortality rate. POCUS offers a safe, low-cost, and less invasive bedside tool for examining arteries and veins, besides its many other applications.
For learners, the anatomical difference between arteries and veins can also be better understood with the help of POCUS. Arteries are thicker walled and pulsatile; veins are thinner walled, may have valves, and collapse when compressed.
Arteries may be difficult to palpate if they are deeper, have reduced blood flow, or a practitioner does not know the anatomic landmarks or is inexperienced. During an examination, while palpation enables an understanding of the intensity, symmetry, and rhythm of blood flow, POCUS can provide exact information on the underlying anatomy and location of the blood vessels. For example, the dorsalis pedis is a major artery that runs over the dorsal foot. It can become impalpable if the flow is obstructed. In such a condition, POCUS can help to detect the absence of blood flow.&#160;
Consider the internal jugular vein or IJV, which drains venous blood from the brain and superficial veins of the face and finally delivers the blood to the right atrium of the heart. Visualization of the internal jugular vein under ultrasound can improve inspection for jugular venous distension.
Among the arteries, the aorta is the main artery that carries oxygenated blood from the heart and branches off to deliver blood to the rest of the body. The portion of the aorta that passes through the abdomen, from the diaphragm to the umbilical area, is known as the abdominal aorta. The abdominal aorta is examined using POCUS to diagnose life-threatening conditions such as abdominal aortic aneurysm&#8212; a swelling in the aorta, or aortic dissection&#8212; a tear in the artery.&#160;
The conceptual knowledge of the vascular system combined with the technical skills of using palpation and ultrasound can help make life-saving diagnoses during physical examination.
In this video, we will demonstrate how to use POCUS to facilitate learning the examination of veins and arteries.

Source: Joseph H. Donroe, Rachel Liu; Yale School of Medicine, USA
Vascular diseases make up most cases of emergency hospitalization and carry a high ...

Education

JoVE Science Education

Clinical Skills

Physical Examinations IV

High-frequency Ultrasound Imaging of the Abdominal Aorta

Source: Amelia R. Adelsperger, Evan H. Phillips, and <a href="https://www.jove.com/author/Craig+J._Goergen">Craig J. Goergen</a>, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
High-frequency ultrasound systems are used to acquire high resolution images. Here, the use of a state-of-the-art system will be demonstrated to image the morphology and hemodynamics of small pulsatile arteries and veins found in mice and rats. Ultrasound is a relatively inexpensive, portable, and versatile method for the noninvasive assessment of vessels in humans as well as large and small animals. These are several key advantages that ultraound offers compared to other techniques, such as computed tomography (CT), magnetic resonance imaging (MRI), and near-infrared fluorescence tomography (NIRF). CT requires ionizing radiation and MRI can be prohibitively expensive and even impractical in some scenarios. NIRF, on the other hand, is limited by the penetration depth of light required to excite the fluorescent contrast agents.
Ultrasound has limitations in terms of imaging depth; however, this may be overcome by sacrificing resolution and using a lower frequency transducer. Abdominal gas and excess body weight can severely diminish image quality. In the first case, the propagation of sound waves is limited, while in the latter case, they are attenuated by overlying tissues, such as fat and connective tissue. As a result, no contrast or faint contrast may be observed. Finally, ultrasound is a highly user-dependent technique, requiring the sonographer to be familiar with anatomy and to be able to work around issues, such as the appearance of imaging artifacts or acoustic interference.

High-frequency Ultrasound Imaging and Image Acquisition

Source: Amelia R. Adelsperger, Evan H. Phillips, and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, 
...

An Approach to Point-Of-Care Ultrasound Evaluation of the Abdominal Aorta

Samenvatting

Meer video's verkennen

Hoofdstukken in deze video