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 border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>M9 Ultrasound Machine&#160;</td>
			<td>Mindray&#160;</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.

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

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

We seek to demonstrate the use of point-of-care ultrasound or POCUS to evaluate the anatomy and pathology of the abdominal aorta. POCUS has excellent sensitivity and specificity for the evaluation of abdominal aortic aneurysm, and excellent specificity for the evaluation of abdominal aortic dissection. Some of the challenges include ensuring POCUS users have adequate training and ensuring they can identify pathology and artifacts with accuracy.This protocol is comprehensive and can be performed and interpreted by the same individual in less than five minutes. This is faster than computed tomography angiography, especially when the patient is critically ill and not stable enough to leave the critical care area for an imaging test.

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&#39;s diameter, a...

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

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.

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

Probe Selection and Machine Presets for Point-of-Care Ultrasound of the Abdominal Aorta

To perform a point of care ultrasound evaluation of the abdominal aorta, select a 2.5 to 3.5 megahertz curvilinear probe, which provides the best visualization for most adults. Alternatively, use the phased array probe of 1 to 5 megahertz, commonly called cardiac probe, which is typically used for echocardiography. Use the abdominal preset on the machine regardless of the probe used.Set the mode to B mode or two-dimensional gray scale and the depth to 20 centimeters. Adjust the depth once the aorta is visualized to keep the aorta in the midfield of the screen. Choose a lower frequency range for patients with a high body mass index to improve image acquisition.

Imaging the Abdominal Aorta in the Transverse Plane Using Point-of-Care Ultrasound

To begin scanning, position the patient's supine with the abdomen exposed. Hip flexion, if tolerated by the patient, relaxes the abdominal muscles and may improve image acquisition. Apply ultrasound gel to the transducer.Orient the transducer and the transverse plane with the indicator toward the patient's right. Ensure that the indicator position matches the one displayed on the screen. Place the transducer just distal to the patient's xiphoid process and apply light pressure to visualize the anterior aspect of the vertebra with its hyperechoic shadow casting arch.Slide the transducer coddly until the celiac trunk is visualized. The celiac trunk is short and quickly bifurcates into the hepatic artery and splenic artery, which together form the seagull sign. Capture these images for later review by clicking the button on the system that records clips.Slide the transducer coddly to view the superior mesenteric artery or SMA. Coming off the anterior aorta, SMA follows a path parallel to the aorta to course inferiorly. The splenic vein courses anterior to the SMA and the left renal vein courses between the SMA and the aorta.Measure the AP diameter of the suprarenal aorta by optimizing a live image of the aorta in this location, and then pressing the system's freeze button. Press caliper or measure and move the track ball or touch pad of the system to the outer edge of the anterior wall, the adventitia and click select. Next, move the track ball or touch pad again to the outer edge of the posterior wall and click select.Wait for the system to generate a measurement. Click the button on the system that saves still images to save this image as a still image containing the measurement. Continue scanning in a transverse plane to visualize the entirety of the aorta through the bifurcation and capture the images.When a live image of the distal aorta is optimized, measure the AP diameter of the infrarenal aorta. Press caliper or measure and move the track ball or touch pad of the system to the outer edge of the anterior wall, the adventitia and click select. Move the track ball or touch pad again to the outer edge of the posterior wall and click select.Wait for the system to generate a measurement. Save the still image as demonstrated previously. Adjust the depth as the abdominal aorta courses coddly through the abdomen becoming more superficial and tapering slightly.Continue scanning coddly through the aortic bifurcation into the left and right iliac arteries. Adjusting the depth to maintain the aorta in vertebral body in the middle of the screen. Capture images while scanning through the bifurcation.When imaging the abdominal aorta in the transverse plane, an aorta measuring greater than 3 centimeters was considered aneurysmal. Such aneurysms also showed the presence of a hematoma filling most of the lumen. The presence of an intimal flap within the lumen of the aorta indicated aortic dissection.Depending on the chronicity of the dissection, the flap was either thin and moved with the pulsations of the aorta or thickened and had an adjacent hematoma. An acute thoracic aortic dissection was found to extend through the abdominal aorta and into the right iliac artery.

Imaging the Abdominal Aorta in the Longitudinal and Coronal Plane Using Point-of-Care Ultrasound

To begin scanning, position the patient's supine with the abdomen exposed. Hip flexion, if tolerated by the patient, relaxes the abdominal muscles and may improve image acquisition. Apply ultrasound gel to the transducer.Place the transducer transversely in the proximal abdomen, and the transverse plane, with the indicator toward the patient's right. Ensure that the indicator position matches the one displayed on the screen. Starting in the subxiphoid area, scan to obtain a transverse view of the aorta.Once the transverse view of the aorta is optimized, rotate the probe clockwise with the indicator pointing towards the patient's head. Following the aorta as the image becomes longitudinal on the screen. Acquire images while scanning caudally, examining for aneurysmal dilations, and save these images for later review by clicking the button on the system that records clip.To obtain a longitudinal view of the aorta in the coronal plane, if possible, position the patient in the left lateral decubitus position for better image acquisition. Place the transducer in the coronal plane at the mid axillary line on the patient's right with the indicator pointing cranially. Scan the aorta in the coronal plane.The aorta will be visualized deep into the IVC if both vessels are imaged. The abdominal aortic pseudo thrombus was a reverberation artifact resulting from the reflection of the ultrasound beam between the anterior and posterior walls of the SMA.

1.5K Views.  University of Illinois Hospital.  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.

Imaging the Abdominal Aorta with Point-of-Care Ultrasound

Summary