All procedures performed in this study involving human participants were in accordance with the ethical standards of the Duke University Health System institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Images included were performed on the authors themselves for normal images and as part of routine educational ultrasound scans done for teaching purposes for positive images, with preceding consent per institutional standards. Patients were included based on the following criteria: any patient with acute kidney injury, decreased urinary output, or any other reason to suspect abnormal kidney function. Exclusion criteria included patients with an open abdomen. Pain is a relative contraindication to ultrasound exams, especially when the pain is so severe that it prohibits probe placement (e.g., intraabdominal hypertension). The reagents and the equipment used are listed in the Table of Materials.
Terminology: the three planes of the body are called coronal, sagittal, and transverse 
This can be confusing because the latter term (&#34;transverse&#34;) can also be used to refer to the short axis of a single organ alongside the use of the term &#34;longitudinal&#34; to refer to the long axis of the organ. To minimize confusion, this protocol will exclusively use coronal, sagittal, and transverse to refer to planes in the human body and will use long-axis and short-axis to refer to the planes of the kidney. Further, since the bladder&#39;s dynamic shape prevents it from having a permanent long- or short-axis, the two views of the bladder will only be named based on which one of two to the plane of the body that the view aligns with: sagittal or transverse.
1. Transducer selection
<ol>
	<li>Select a low-frequency transducer: preferably, this should be the curvilinear transducer (2-5 MHz). If a curvilinear transducer is not available, a sector array (aka &#34;phased array&#34;; 1-5 MHz) can serve as a substitute. 
	NOTE: The curvilinear transducer is the best choice for visualizing the kidney through a single view because its footprint creates a large field of view, and its low-frequency piezoelectric crystals permit penetration deep enough into the body. However, the curvilinear probe can be difficult to use when looking at kidneys through the ribs.</li>
</ol>
2. Machine settings
<ol>
	<li>Set the depth so that the kidney will appear in the middle third of the ultrasound screen (the typical setting is between 16 cm and 20 cm).</li>
	<li>Set the gain such that the renal medullary pyramids appear anechoic (black), the renal sinus complex appears hyperechoic (bright), and the kidney cortex appears intermediate between these extremes.</li>
</ol>
3. Mode and presets
<ol>
	<li>Select two-dimensional (2D) mode, also called brightness mode (B-mode). This is a 2-dimensional greyscale ultrasound mode.</li>
	<li>After activating the 2D mode, select the abdominal preset.</li>
</ol>
4. Patient positioning
<ol>
	<li>For most of the exam, position the patient supine. 
	NOTE: When imaging the right kidney, it may become necessary to reposition the patient in the left lateral recumbent position for better visualization of the right kidney. When imaging the left kidney, it may become necessary to reposition the patient in the right lateral recumbent position for better visualization of the left kidney.</li>
	<li>Before scanning, expose the patient&#39;s lower chest and abdomen.</li>
	<li>Position the ultrasound machine so that the sonographer&#39;s dominant hand can hold the ultrasound probe. This allows for finer manipulation of the ultrasound probe and frees up the non-dominant hand for operating the ultrasound machine. 
	NOTE: Right-handed sonographers should position themselves with the patient on their right side and vice versa.</li>
</ol>
5. Imaging the right kidney
<ol>
	<li>Gel application
	<ol>
		<li>Apply gel to the ultrasound probe directly to maximize scanning efficiency prior to acquiring each image.</li>
	</ol>
	</li>
	<li>Coronal view
	<ol>
		<li>Place the probe on the right flank, along the mid-axillary line, 5th-7th intercostal space, indicator pointing cranially (Figure 1).</li>
		<li>Adjust the probe position (sliding up/down, angling anterior/posterior) until the right kidney is seen in its maximal longitudinal extent (see Figure 2).</li>
		<li>Fan through anteriorly to posteriorly to screen for hydronephrosis and other gross abnormalities (Video 1).</li>
		<li>Cine clip acquisition: For machines configured for retrospective image acquisition, click on acquire prior to step 5.2.4. For machines configured for prospective image acquisition, click on acquire after step 5.2.4.</li>
	</ol>
	</li>
	<li>Kidney long-axis diameter measurement
	<ol>
		<li>Center the kidney in the image, click on Freeze, and measure the height of the kidney (Figure 3).</li>
		<li>Click on Save (or the equivalent button).</li>
	</ol>
	</li>
	<li>Transverse view
	<ol>
		<li>After centering on the right kidney, rotate the probe 90 degrees clockwise until the probe marker is facing anteriorly, revealing the kidney in the transverse view (Figure 4).</li>
		<li>Adjust the probe position (sliding up/down, angling anterior/posterior) until the right kidney is seen in its maximal size in this transverse plane (Figure 5).</li>
		<li>Fan through cranially to caudally to screen for hydronephrosis and other gross abnormalities (Video 2). Repeat the step.</li>
	</ol>
	</li>
</ol>
6. Imaging the left kidney
<ol>
	<li>Repeat steps 5.1-5.3 for the left kidney.</li>
</ol>
7. Imaging the bladder
<ol>
	<li>Gel application: repeat step 5.1.1.</li>
	<li>Transverse view
	<ol>
		<li>Probe position: position the probe just cranial to the pubic symphysis with the probe indicator pointing toward patient&#39;s right side (Figure 6).</li>
		<li>Angle the ultrasound beam caudally into the pelvis until the bladder is visible in its maximal size.</li>
		<li>Image optimization
		<ol>
			<li>Adjust depth until the bladder is visible in the middle third of the screen.</li>
			<li>Adjust gain until the bladder lumen is grossly anechoic (black) and the tissue plane directly posterior to the bladder is slightly hyperechoic (bright).</li>
		</ol>
		</li>
		<li>Cine clip acquisition
		<ol>
			<li>Fan through the bladder from cranial to caudal to visualize the entire structure. Repeat step 5.2.3.</li>
		</ol>
		</li>
		<li>Transverse bladder dimension measurements
		<ol>
			<li>Center the view on the bladder&#39;s maximal dimension, click on Freeze and measure the anterior-posterior and lateral-to-medial diameters of the bladder (Figure 7, left panel).</li>
			<li>Click on Save (or the equivalent button).</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Sagittal view
	<ol>
		<li>Maintaining the transverse view, center the view on the bladder and rotate the probe 90 degrees clockwise until the probe marker is facing cranially, revealing the kidney in the sagittal plane (Figure 8).</li>
		<li>Cine clip acquisition
		<ol>
			<li>Fan through the bladder from side to side to visualize the entire structure. Repeat step 5.2.3.</li>
		</ol>
		</li>
		<li>Transverse bladder dimension measurements
		<ol>
			<li>Center the view on the bladder&#39;s maximal dimension, click on Freeze and measure the cranial-to-caudal diameter of the bladder (Figure 7, right panel).</li>
			<li>Click on Save (or the equivalent button).</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>

Advancing Bedside Care: A Multidisciplinary Guide to Kidney-Genitourinary POCUS

<ol>
	<li>Rewa, O., Bagshaw, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+kidney+injury+-+epidemiology,+outcomes+and+economics.">Acute kidney injury - epidemiology, outcomes and economics.</a> Nat Rev Nephrol. 10 (4), 193-207 (2014).</li><li>National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renal+Data+System.+2023+USRDS+annual+data+report:+Epidemiology+of+kidney+disease+in+the+United+States.">Renal Data System. 2023 USRDS annual data report: Epidemiology of kidney disease in the United States.</a> National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases. , (2023).</li><li>Susantitaphong, 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=World+incidence+of+AKI:+A+meta-analysis.">World incidence of AKI: A meta-analysis.</a> Clin J Am Soc Nephrol. 8 (9), 1482-1493 (2013).</li><li>Kellum, J. 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=Classifying+AKI+by+urine+output+versus+serum+creatinine+level.">Classifying AKI by urine output versus serum creatinine level.</a> J Am Soc Nephrol. 26 (9), 2231-2238 (2015).</li><li>Khaled Shawwa, K., 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=Heterogeneity+in+acute+kidney+injury+management+in+critically+ill+patients:+National+survey.">Heterogeneity in acute kidney injury management in critically ill patients: National survey.</a> J Nurse Pract. 19 (10), 104776 (2023).</li><li>Diaz-Gomez, J. L., Mayo, P. H., Koenig, S. J. <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+ultrasonography.">Point-of-care ultrasonography.</a> N Engl J Med. 385 (17), 1593-1602 (2021).</li><li>Koratala, A., Bhattacharya, D., Kazory, A. <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+renal+ultrasonography+for+the+busy+nephrologist:+A+pictorial+review.">Point of care renal ultrasonography for the busy nephrologist: A pictorial review.</a> World J Nephrol. 8 (3), 44-58 (2019).</li><li>Fischer, E. 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=Hospitalist-operated+compression+ultrasonography:+A+point-of-care+ultrasound+study+(hocus-pocus).">Hospitalist-operated compression ultrasonography: A point-of-care ultrasound study (hocus-pocus).</a> J Gen Intern Med. 34 (10), 2062-2067 (2019).</li><li>Sibley, S., 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+hydronephrosis+in+emergency+department+patients+with+suspected+renal+colic.">Point-of-care ultrasound for the detection of hydronephrosis in emergency department patients with suspected renal colic.</a> Ultrasound J. 12 (1), 31 (2020).</li><li>Yaxley, J., Yaxley, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obstructive+uropathy+-+acute+and+chronic+medical+management.">Obstructive uropathy - acute and chronic medical management.</a> World J Nephrol. 12 (1), 1-9 (2023).</li><li>Rahbari-Oskoui, F., O'Neill, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+and+management+of+acquired+cystic+kidney+disease+and+renal+tumors+in+ESRD+patients.">Diagnosis and management of acquired cystic kidney disease and renal tumors in ESRD patients.</a> Semin Dial. 30 (4), 373-379 (2017).</li><li>Bhutani, H., 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=A+comparison+of+ultrasound+and+magnetic+resonance+imaging+shows+that+kidney+length+predicts+chronic+kidney+disease+in+autosomal+dominant+polycystic+kidney+disease.">A comparison of ultrasound and magnetic resonance imaging shows that kidney length predicts chronic kidney disease in autosomal dominant polycystic kidney disease.</a> Kidney Int. 88 (1), 146-151 (2015).</li><li>Liu, C., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+utility+of+ultrasonographic+evaluation+in+acute+kidney+injury.">Clinical utility of ultrasonographic evaluation in acute kidney injury.</a> Transl Androl Urol. 9 (3), 1345-1355 (2020).</li><li>Wong, J., 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=Barriers+to+learning+and+using+point-of-care+ultrasound:+A+survey+of+practicing+internists+in+six+north+American+institutions.">Barriers to learning and using point-of-care ultrasound: A survey of practicing internists in six north American institutions.</a> Ultrasound J. 12 (1), 19 (2020).</li><li>Ozmen, C. 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=Ultrasound+as+a+diagnostic+tool+to+differentiate+acute+from+chronic+renal+failure.">Ultrasound as a diagnostic tool to differentiate acute from chronic renal failure.</a> Clin Nephrol. 74 (1), 46-52 (2010).</li><li>Soni, N. J., Arntfield, R., Kory, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Point-of-care ultrasound. Second edition. , 229-230 (2020).</li><li>O'Neill, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sonographic+evaluation+of+renal+failure.">Sonographic evaluation of renal failure.</a> Am J Kidney Dis. 35 (6), 1021-1038 (2000).</li><li>Koratala, A., Bhattacharya, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extra-renal+pelvis+mimicking+hydronephrosis:+A+case+for+caution.">Extra-renal pelvis mimicking hydronephrosis: A case for caution.</a> Clin Case Rep. 5 (10), 1720-1721 (2017).</li><li>Muglia, V. F., Westphalen, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bosniak+classification+for+complex+renal+cysts:+History+and+critical+analysis.">Bosniak classification for complex renal cysts: History and critical analysis.</a> Radiol Bras. 47 (6), 368-373 (2014).</li><li>Silverman, S. G., 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=Bosniak+classification+of+cystic+renal+masses,+version+2019:+An+update+proposal+and+needs+assessment.">Bosniak classification of cystic renal masses, version 2019: An update proposal and needs assessment.</a> Radiology. 292 (2), 475-488 (2019).</li><li>Burgan, C. M., Sanyal, R., Lockhart, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasound+of+renal+masses.">Ultrasound of renal masses.</a> Radiol Clin North Am. 57 (3), 585-600 (2019).</li><li>Weber, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sonography+of+benign+renal+cystic+disease.">Sonography of benign renal cystic disease.</a> Radiol Clin North Am. 44 (6), 777-786 (2006).</li><li>Pei, Y., Watnick, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diagnosis+and+screening+of+autosomal+dominant+polycystic+kidney+disease.">Diagnosis and screening of autosomal dominant polycystic kidney disease.</a> Adv Chronic Kidney Dis. 17 (2), 140-152 (2010).</li><li>Hines, J. J., Eacobacci, K., Goyal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+incidental+renal+mass-+update+on+characterization+and+management.">The incidental renal mass- update on characterization and management.</a> Radiol Clin North Am. 59 (4), 631-646 (2021).</li><li>Baldini, G., Bagry, H., Aprikian, A., Carli, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Postoperative+urinary+retention:+Anesthetic+and+perioperative+considerations.">Postoperative urinary retention: Anesthetic and perioperative considerations.</a> Anesthesiology. 110 (5), 1139-1157 (2009).</li><li>Bih, L. I., Ho, C. C., Tsai, S. J., Lai, Y. C., Chow, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bladder+shape+impact+on+the+accuracy+of+ultrasonic+estimation+of+bladder+volume.">Bladder shape impact on the accuracy of ultrasonic estimation of bladder volume.</a> Arch Phys Med Rehabil. 79 (12), 1553-1556 (1998).</li><li>Goertz, J. K., Lotterman, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Can+the+degree+of+hydronephrosis+on+ultrasound+predict+kidney+stone+size.">Can the degree of hydronephrosis on ultrasound predict kidney stone size.</a> Am J Emerg Med. 28 (7), 813-816 (2010).</li><li>Noble, V. E., Brown, D. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Renal+ultrasound.">Renal ultrasound.</a> Emerg Med Clin North Am. 22 (3), 641-659 (2004).</li><li>Onen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Grading+of+hydronephrosis:+An+ongoing+challenge.">Grading of hydronephrosis: An ongoing challenge.</a> Frontiers in Pediatrics. 8, 458 (2020).</li><li>Koratala, A., Reisinger, N. <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+training+in+nephrology:+A+leap+forward,+not+merely+a+check+mark.">Point-of-care ultrasound training in nephrology: A leap forward, not merely a check mark.</a> Kidney Med. 6 (1), 100752 (2024).</li></ol>

MAS reports receiving honoraria from Elsevier-Nephrology Secrets; serving as a member of the American Board of Internal Medicine Nephrology Board; receives honoraria from NKF for being on the executive committee for NephMadness; receives honoraria from Medscape for CKD Podcast Series; Receives honoraria for serving as communications editor for ASN Journals Portfolio (JASN, CJASN, Kidney360). YSB reports receiving honoraria from the American Society of Anesthesiologists for Editorial Board work on Point-of-Care Ultrasound and from OpenAnesthesia.org for creating educational content related to POCUS. The remaining authors have no disclosures.

AKI commonly manifests in critically ill hospitalized patients, amplifying the risk of mortality. To proficiently execute the steps outlined above and differentiate normal from pathologic findings, a comprehensive understanding of normal anatomy and ultrasonographic appearances is essential, along with precise adherence to the protocol&#39;s specific steps.
Critical anatomy/steps in the protocol 
Kidney- The kidneys are retroperitoneal organs that lie in an obliq...

Acute kidney injury (AKI), resulting from a variety of etiologies, is a frequent medical diagnosis identified in hospitalized patients. AKI precipitates an abrupt decrease in kidney function that leads to an accumulation of extracellular fluid, urea, and other nitrogenous waste products, along with the dysregulation of electrolytes. Moreover, the diagnosis of AKI portends worse short-term and long-term outcomes and is associated with the consumption of greater healthcare resources1. According to the United States Renal Data System (USRDS), among Medicare Fee-For-Service beneficiaries in 2020, the rate of hospitalization with AKI was 62 admissions per 1000 patient years2. Furthermore, a systematic review of 154 studies that adopted the Kidney Disease Improving Global Outcomes (KDIGO) AKI diagnostic criteria found that among the 3,585,911 people in these trials, primarily from North America, Northern Europe, and Eastern Asia, the incidence of AKI in different inpatient settings ranged from 20%-32%3. In the inpatient setting, AKI is commonly identified in the intensive care unit and is associated with increased mortality4. Point-of-care ultrasound (POCUS) machines are readily available in settings such as the ICU, but diagnostic kidney-GU ultrasound is often underused despite being able to quickly evaluate several etiologies of AKI5.
Compared to consultative ultrasound, in which a patient's primary provider orders a formal ultrasound to be performed by a radiology technician and read by a radiologist, diagnostic POCUS is performed and interpreted by a patient's primary provider at the point of care6. There is growing evidence that non-radiologists can effectively and accurately use diagnostic POCUS for a variety of conditions7. For instance, the 2019 Hospitalist-Operated Compression Ultrasonography: a Point-of-Care Ultrasound Study (HOCUS-POCUS) prospective cohort study compared hospitalist-performed deep vein thrombosis (DVT) compressive POCUS to consultative technician/radiologist performed vascular DVT ultrasound. The study showed similar accuracy of hospitalist-performed POCUS to technician/radiologist-performed consultative vascular ultrasound with sensitivity of 100% and specificity of 96%8. Similarly, a 2020 study found kidney-GU POCUS performed by Emergency Department providers of varied experience had moderate accuracy (specificity of 72% and sensitivity of 77%) in detecting hydronephrosis when compared to computed tomography scan9. Importantly, primary-provider performed POCUS allows for more timely diagnosis and intervention compared to technician/radiologist imaging.
Causes of AKI can be divided into pre-renal (hemodynamically mediated injury), intra-renal (glomerular or interstitial pathologies), and post-renal (urologic etiologies, most commonly obstructive uropathy). The latter, especially, can be diagnosed with POCUS. Obstructive uropathy has an annual incidence of 1.7 per 1000 people and has been estimated to account for about 10% of acute and chronic kidney disease10. From prostatic hyperplasia to nephrolithiasis, there are many causes of urinary obstruction. The main pathologic manifestation of these conditions at the level of the kidney is hydronephrosis. This is easily visualized on POCUS, and speed in diagnosis can be critical in treating acutely ill patients with kidney failure. 
Beyond AKI, POCUS remains a cost-effective and safe modality for evaluating chronic kidney disease. POCUS can be used to identify lesions indicative of renal cell carcinoma, given the ability to visualize cysts greater than or equal to 3 cm and to discriminate characteristics deemed concerning for malignancy11. POCUS allows for the rapid evaluation of autosomal dominant polycystic kidney disease (ADPKD), avoiding unnecessary scheduling of kidney biopsies and expensive lab work. Additionally, ultrasonographic measurement of kidney length was shown to prognosticate risk of progression in early ADPKD when compared to the gold standard magnetic resonance-based, height-adjusted total kidney volume measurement (htTKV)12. 
While computed tomography scans have an advantage in detecting neoplasms, stones, and calcifications, there has been no proven benefit of computed tomography over ultrasonography in the diagnosis of AKI etiologies13. Furthermore, some patients may be too sick to move out of their rooms, precluding transport to the CT scanner or even the radiology suite for a technician/radiologist to perform the consultative ultrasound. In these cases, POCUS provides a safe and reliable diagnostic alternative. Despite this, diagnostic kidney-GU POCUS remains an underused tool, likely due to a lack of training among frontline clinicians14. To address this knowledge gap, this narrative review brings together the expertise of multiple specialties (hospital medicine, critical care, anesthesiology, and nephrology) to propose an evidence-based kidney-GU POCUS image acquisition protocol, including indications/contraindications, patient positioning, transducer selection, acquisition sequence, and exam limitations. Finally, we describe foundational concepts in kidney-GU ultrasound image interpretation, including key abnormal findings that every bedside clinician performing this modality should know.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Curvilinear Transducer</td>
			<td>Philips</td>
			<td>C5-2 USB</td>
			<td>2-5 MHz, also called the abdominal probe</td>
		</tr>
		<tr>
			<td>Curvilinear Transducer</td>
			<td>SonoSite</td>
			<td>C5-1</td>
			<td>1-5 MHz, also called the abdominal probe</td>
		</tr>
		<tr>
			<td>Edge 1 ultrasound machine</td>
			<td>SonoSite</td>
			<td></td>
			<td>Used to obtain a subset of the Figures and Videos</td>
		</tr>
		<tr>
			<td>Phased-Array Transducer</td>
			<td>Philips</td>
			<td></td>
			<td>1-5 MHz, also called the cardiac probe</td>
		</tr>
		<tr>
			<td>Phased-Array Transducer</td>
			<td>SonoSite</td>
			<td>P5-1</td>
			<td>1-5 MHz, also called the cardiac probe</td>
		</tr>
		<tr>
			<td>Ultrasound system</td>
			<td>Philips</td>
			<td>Affiniti30</td>
			<td>Used to obtain a subset of the Figures and Videos</td>
		</tr>
	</tbody>
</table>

point-of-care kidney and genitourinary ultrasound in adults: image acquisition

A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with diagnostic imaging. Common imaging modalities include either computed tomography or diagnostic ultrasound. Traditionally, ultrasound of the kidney-genitourinary system has required consultative teams consisting of a sonographer performing image acquisition and a radiologist performing image interpretation. However, diagnostic point-of-care ultrasound (POCUS) has recently emerged as a useful tool to troubleshoot acute kidney injury at the bedside. Studies have shown that non-radiologists can be trained to perform diagnostic POCUS of the kidneys and bladder with high accuracy for a set number of important conditions. Currently, diagnostic POCUS of the kidney-genitourinary system remains underused in actual clinical practice. This is likely because image acquisition for this organ system is unfamiliar to most clinicians in specialties that encounter acute kidney injury, including primary care, emergency medicine, intensive care, anesthesiology, nephrology, and urology. To address this multi-specialty educational gap, this narrative review was developed by a multi-disciplinary group to provide a specialty-agnostic framework for kidney-genitourinary POCUS image acquisition: indications/contraindications, patient positioning, transducer selection, acquisition sequence, and exam limitations. Finally, we describe foundational concepts in kidney-genitourinary ultrasound image interpretation, including key abnormal findings that every bedside clinician performing this modality should know.

Sonographically normal exam
Normal kidney ultrasound 
The echogenicity of the kidney capsule and limited anatomic variability (except for the occasional pelvic kidney or the even more rare horseshoe kidney) allow for easy identification of the kidneys with bedside POCUS. The kidneys will have a typical bean-shaped appearance, measuring on average 9-13 cm, though size varies with patient height and weight (Figure 2, Vi...

Author Spotlight: Developing a Bedside Protocol for Kidney and Genitourinary Ultrasonography

Point-of-care ultrasound (POCUS) of the renal and genitourinary (renal-GU) system can help to screen for certain causes of kidney dysfunction. However, despite its clinical utility, renal-GU POCUS remains underutilized due to a lack of training among clinicians. To address this gap, this article describes renal-GU image acquisition and interpretation.

Point-of-Care Kidney and Genitourinary Ultrasound in Adults: Image Acquisition

A range of conditions involving the kidneys and urinary bladder can cause organ-threatening complications that are preventable if diagnosed promptly with ...

point-care-kidney-genitourinary-ultrasound-adults-image

Research

Education

JoVE Journal

JoVE Core

Anatomy and Physiology

Medicine

Unit 1

The Urinary System

SCIENTISTS IN ACTION

846 Views.  Duke University School of Medicine. Point-of-care ultrasound (POCUS) of the renal and genitourinary (renal-GU) system can help to screen for certain causes of kidney dysfunction. However, despite its clinical utility, renal-GU POCUS remains underutilized due to a lack of training among clinicians. To address this gap, this article describes renal-GU image acquisition and interpretation.

Video: Author Spotlight: Developing a Bedside Protocol for Kidney and Genitourinary Ultrasonography

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 ...

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 ...

Troubleshooting FoCUS Image Acquisition: Patient Positioning, Transducer Manipulation, and Image Optimization

Focused cardiac ultrasound (FoCUS) is a limited, clinician-performed application of echocardiography to add real-time information to patient care. These bedside exams are problem oriented, rapidly and repeatedly performed, and largely qualitative in nature. Competency in FoCUS includes mastery of the stereotactic and psychomotor skills required for transducer manipulation and image acquisition. Competency also requires the ability to optimize the setup, troubleshoot image acquisition, and understand the sonographic limitations because of complex clinical environments and patient pathology. This article presents concepts for successful, high-quality two-dimensional (B-mode) image acquisition in FoCUS.
Concepts of high-quality image acquisition can be applied to all established sonographic windows of the FoCUS exam: the parasternal long-axis (PLAX), parasternal short-axis (PSAX), apical four chamber (A4C), subcostal fourchamber (SC4C), and the inferior vena cava (IVC). The apical five-chamber (A5C) and subcostal short-axis (SCSA) views are mentioned, but are not discussed in-depth. A pragmatic figure illustrating the movements of the phased array transducer is also provided to serve as a cognitive aid during FoCUS image acquisition.

Here, we present a protocol to allow providers to perform focused cardiac ultrasound (FoCUS) in the clinical environment. We describe methods of transducer manipulation, review common pitfalls of transducer movements, and suggest tips to optimize phased array transducer use.

Focused cardiac ultrasound (FoCUS) is a limited, clinician-performed application of echocardiography to add real-time information to patient care. These ...

Point-of-Care Lung Ultrasound in Adults: Image Acquisition

Consultative ultrasound performed by radiologists has traditionally not been used for imaging the lungs, as the lungs&#39; air-filled nature normally prevents direct visualization of the lung parenchyma. When showing the lung parenchyma, ultrasound typically generates a number of non-anatomic artifacts. However, over the past several decades, these artifacts have been studied by diagnostic point-of-care ultrasound (POCUS) practitioners, who have identified findings that have value in narrowing the differential diagnoses of cardiopulmonary dysfunction. For instance, in patients presenting with dyspnea, lung POCUS is superior to chest radiography (CXR) for the diagnosis of pneumothorax, pulmonary edema, lung consolidations, and pleural effusions. Despite its known diagnostic value, the utilization of lung POCUS in clinical medicine remains variable, in part because training in this modality across hospitals remains inconsistent. To address this educational gap, this narrative review describes lung POCUS image acquisition in adults, including patient positioning, transducer selection, probe placement, acquisition sequence, and image optimization.

Point-of-care ultrasound (POCUS) of the lungs provides quick answers in rapidly changing clinical scenarios. We present an efficient and informative protocol for image acquisition for use in acute care settings.

Consultative ultrasound performed by radiologists has traditionally not been used for imaging the lungs, as the lungs&#39; air-filled nature normally ...

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 ...

A Modified Sonographic Algorithm for Image Acquisition in Life-Threatening Emergencies in the Critically Ill Newborn

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h equipment availability. In 2018, the sonographic algorithm for life-threatening emergencies (SAFE) protocol was published, which allows the assessment of neonates with sudden decompensation to identify abnormal contractility, tamponade, pneumothorax, and pleural effusion. In the study unit (with a consulting neonatal hemodynamics and POCUS service), the algorithm was adapted by including consolidated core steps to support at-risk newborns, aiding clinicians in managing cardiac arrest, and adding views to verify correct intubation. This paper presents a protocol that can be applied in the NICU and the delivery room (DR) in relation to three scenarios: cardiac arrest, hemodynamic deterioration, or respiratory decompensation. 
This protocol can be performed with a state-of-the-art ultrasound machine or an affordable handheld device; the image acquisition protocol is carefully detailed. This method was designed to be learned as a general competence to obtain the timely diagnosis of life-threatening scenarios; the method aims to save time but does not represent a substitute for comprehensive and standardized hemodynamic and radiological analyses by a multidisciplinary team, which might not universally be on call but needs to be involved in the process. From January 2019 to July 2022, in our center, 1,045 hemodynamic consultation/POCUS consults were performed with 25 patients requiring the modified SAFE protocol (2.3%), and a total of 19 procedures were performed. In five cases, trained fellows on call resolved life-threatening situations. Clinical examples are provided that show the importance of including this technique in the care of critical newborns.

Here, we present a protocol that can be applied in the neonatal intensive care unit and the delivery room in relation to three scenarios: cardiac arrest, hemodynamic deterioration, or respiratory decompensation. This protocol can be performed with a state-of-the-art ultrasound machine or an affordable handheld device; an image acquisition protocol is carefully detailed.

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h ...

Optic Nerve Sheath Point of Care Ultrasound: Image Acquisition

The goal of this protocol is to develop a standardized method for acquiring images of the optic nerve sheath and measuring the optic nerve sheath diameter (ONSD). Diagnostic ultrasound of the ONSD to detect intracranial hypertension has traditionally faced many problems because of methodologic discrepancies. Due to inconsistencies in the measuring techniques, the potential for ONSD to become a non-invasive bedside monitoring tool for ICP has been hampered. However, establishing a transparent, consistent methodology for measuring the ONSD would support its use as a valid and reliable method of identifying intracranial hypertension. This is important as it has both high sensitivity and specificity in acute care settings. This narrative review describes ONSD POCUS image acquisition, including patient positioning, transducer selection, probe placement, the acquisition sequence, and image optimization. Further, visual aids are provided to assist in real-time during image acquisition. This method should be considered for patients for whom there are concerns regarding intracranial hypertension but who do not have an intracranial monitor in place.

Point-of-care ultrasound (POCUS) of the optic nerve sheath diameter (ONSD) has been shown to be useful in identifying patients with increased intracranial pressure (ICP). However, the non-standardized technique for this POCUS has hampered its use. We present a standardized image acquisition protocol for use in the acute care setting.

The goal of this protocol is to develop a standardized method for acquiring images of the optic nerve sheath and measuring the optic nerve sheath diameter ...

Imaging the Abdominal Aorta with Point-of-Care Ultrasound

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

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 ...

Gastric Ultrasound Technique for Mitigating Peri-Procedural Aspiration Risk

Gastric Point of Care Ultrasound in Adults: Image Acquisition and Interpretation

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical inquiries related to gastric content. One emerging concern pertains to patients about to undergo sedation and/or endotracheal intubation: the elevated risk of aspiration from the patient&#39;s stomach contents. Aspiration of gastric contents into the lungs poses a serious and potentially life-threatening complication. This occurs more frequently when the stomach is considered &#34;full&#34; and can be affected by the techniques employed for airway management, making it potentially preventable. To mitigate the risk of peri-procedural aspiration, two distinct medical specialties (anesthesiology and critical care medicine) have independently developed techniques to utilize ultrasonography for identifying patients requiring &#34;full stomach&#34; precautions. Due to these separate specialties, the work of each group remains relatively unfamiliar outside its respective field. This article presents descriptions of both techniques for gastric ultrasound. Furthermore, it explains how these approaches can complement each other when one of them falls short. Regarding image acquisition, the article covers the following topics: indications and contraindications, selection of the appropriate probe, patient positioning, and troubleshooting. The article also delves into image interpretation, complete with example images. Additionally, it demonstrates how one of the two techniques can be employed to estimate gastric fluid volume. Lastly, the article briefly discusses medical decision-making based on the findings of this examination.

Author Spotlight: Point-of-Care Ultrasound for Gastric Content Assessment and Risk Stratification in Perioperative Care 

This protocol introduces two methods for image acquisition in gastric ultrasonography. Additionally, tips are provided for interpreting this information to assist in medical decision-making.

Over the past two decades, diagnostic point-of-care ultrasound (POCUS) has emerged as a rapid and non-invasive bedside tool for addressing clinical ...

Ultrasound in Evaluating Diaphragm Dysfunction and Monitoring Treatment

Measuring Diaphragm Thickness and Function Using Point-of-Care Ultrasound

The diaphragm is the main component of the respiratory muscle pump. Diaphragm dysfunction can cause dyspnea and exercise intolerance, and predisposes affected individuals to respiratory failure. In mechanically ventilated patients, the diaphragm is susceptible to atrophy and dysfunction through disuse and other mechanisms. This contributes to failure to wean and poor long-term clinical outcomes. Point-of-care ultrasound provides a valid and reproducible method for evaluating diaphragm thickness and contractile activity (thickening fraction during inspiration) that can be readily employed by clinicians and researchers alike. This article presents best practices for measuring diaphragm thickness and quantifying diaphragm thickening during tidal breathing or maximal inspiration. Once mastered, this technique can be used to diagnose and prognosticate diaphragm dysfunction, and guide and monitor response to treatment over time in both healthy individuals and acute or chronically ill patients.

Author Spotlight: Unraveling the Impact of Mechanical Ventilation on Diaphragm Function and Patient Outcomes 

Diaphragm thickness and function can be assessed in healthy individuals and critically ill patients using point-of-care ultrasound. This technique offers an accurate, reproducible, feasible, and well-tolerated method for evaluating diaphragm structure and function.

The diaphragm is the main component of the respiratory muscle pump. Diaphragm dysfunction can cause dyspnea and exercise intolerance, and predisposes ...