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PEM POCUS Series: Pediatric Renal and Bladder Ultrasound

PEM POCUS fascia iliaca block

Read this tutorial on the use of point of care ultrasonography (POCUS) for pediatric renal and bladder ultrasonography. Then test your skills on the ALiEMU course page to receive your PEM POCUS badge worth 2 hours of ALiEMU course credit.

Module Goals

  1. List the indications for performing a pediatric renal/bladder point-of-care ultrasound (POCUS)
  2. Describe the technique for performing renal/bladder POCUS
  3. Identify hydronephrosis and its appearance at different severities
  4. List the limitations of renal/bladder POCUS
  5. Advanced: Recognize direct and other indirect signs of nephrolithiasis as well as gross renal/bladder structural anomalies such as cysts and masses

Case Introduction: Child with abdominal pain

Serena is a 9-year-old girl who comes into the emergency department complaining of one day of left flank and left lower quadrant pain (LLQ). The pain is intermittent, sharp, severe, and associated with 2 episodes of nonbloody, nonbilious emesis. Her mother denies any fevers, upper respiratory symptoms, sore throat, or diarrhea. She adds that her daughter has complained of 2-3 episodes of dysuria and gross hematuria over the last few days.

On arrival, her vital signs are:

Vital SignFinding
Temperature99 F
Heart Rate115 bpm
Blood Pressure97/50
Respiratory Rate19
Oxygen Saturation (room air)100%

You find her lying on the gurney, uncomfortable appearing, and intermittently crying. She has a normal HEENT, neck, cardiac, respiratory, and back examination. She has no flank tenderness, but she does cry out with palpation of the LLQ and suprapubic areas.

Given her pain with a history of intermittent hematuria and dysuria, you perform a renal and bladder point of care ultrasound (POCUS) examination.

Pediatric Renal and Bladder POCUS

  • Hematuria
  • Flank pain
  • Abdominal distension or palpable mass
  • Anuria, oliguria, or urinary retention
  • Concern for nephrolithiasis
  • Bladder volume assessment prior to urinary catheterization

Probe choice [1]

  • Typically based on the size of the child (Figure 1)
  • If unsure, perform test scans and choose the probe that most effectively provides the desired views and level of detail
ultrasound probe transducers

Figure 1. Ultrasound probes from left to right: linear (nenoates), phased array (infants/younger children), and curvilinear (older children/adolescents)

Pro tips for performing renal/bladder POCUS on a child [1]

  • Addressing potential anxiety leads to a more efficient and comfortable examination.
  • Explain to the parent (and child if old enough), the areas you need to examine.
  • Set up distractions such as toys or videos on a tablet or smartphone
  • When appropriate, demonstrate the probe(s) to the child and apply some ultrasound gel to the back of their hand so they understand it will not be painful.
  • Pre-warmed ultrasound gel is helpful when available.
  • Examine the patient in a position that maximizes comfort and minimizes anxiety.
    • Lay the patient supine when possible. They can lay on the stretcher, or in the parent’s lap if it calms them (Figure 2, left). This is also an optimal position in which the parent can hold a tablet or smart device above the patient’s face as a distractor.
    • If supine positioning is unsuccessful, the patient can be placed upright in their parent’s lap facing away from the sonographer (Figure 2, right). In this position, the parent can hug and hold the patient if needed.
pediatric ultrasound positioning

Figure 2: Patient positioning options: Left (supine) – Patient playing with the distractors during bladder POCUS; Right (upright) – Toddler facing away from sonographer during renal POCUS. Note: Blue dot represents the probe indicator.

Right Kidney (Longitudinal View)

  • Begin in the mid-axillary line around the 10th or 11th intercostal space with the probe marker pointed toward the patient’s head and identify the renal structures (Figure 3).
  • While maintaining probe contact on the skin, tilt it perpendicular to its long axis in each direction (also known as fanning) to assess the entire kidney (Video 1).
Longitudinal view ultrasound right kidney

Figure 3. Longitudinal view of the right kidney: Left – Probe placement in right mid-axillary line; Right – Unlabeled and labeled ultrasound view

Video 1. Longitudinal view of the right kidney

Right Kidney (Transverse View)

  • From the longitudinal view, rotate the probe 90 degrees and fan the probe to assess the entire kidney in the transverse plane (Video 2).
  • Identify the medullary pyramids, calyces, renal cortex, and renal pelvis (Figure 4).
Video 2. Transverse view of the right kidney
right kidney ultrasound transverse view

Figure 4. Transverse ultrasound view of the right kidney with anatomical labels

Left Kidney (Longitudinal View)

  • Place the probe in the left posterior axillary line (the left kidney is slightly more superior and posterior than the right) around the 8th to 10th intercostal space (Figure 5).
  • As performed on the right kidney, identify the relevant structures and fully assess the left kidney by fanning through (Video 3).
left kidney longitudinal ultrasound probe position

Figure 5. Longitudinal view of the left kidney with probe placement in posterior axillary line

Video 3. Longitudinal view of the left kidney

Left Kidney (Transverse View)

  • From the left longitudinal view, rotate the probe 90 degrees. Identify the relevant structures and fully assess the left kidney by fanning through (Video 4).
Video 4. Transverse view of the left kidney

Bladder (Transverse View)

  • With the indicator towards the patient’s right, place the probe on the patient’s midline just above the pubic symphysis and fan the probe downward into the pelvis (Figure 6). The pelvis, the bladder, uterus, prostate, and rectum can be seen in this view (Figure 7).
    • Pro Tip: The bladder is always directly behind the pubic symphysis, so if you cannot locate it, the probe may be too superior. 2
  • Fan through the entire bladder from superior to inferior borders (Video 5).

Figure 6. Probe positioning for transverse view of the bladder

Figure 7. Transvere ultrasound views of the bladder: Left – Uterus identified posteriorly in girl; Right – Prostate identified posteriorly in boy (Images courtesy of Dinh et al.)

Video 5. Transverse view of the bladder

Bladder (Longitudinal/Sagittal View)

  • From the transverse view, rotate the probe 90 degrees clockwise so the indicator is now pointing to the patient’s head.
  • Identify the bladder, bowel gas, uterus or prostate, and rectum (Figure 8). Then fan to scan from one lateral border of the bladder to the other (Video 6).
bladder longitudinal sagittal view

Figure 8. Sagittal view of bladder: Left – Uterus identified posteriorly in girl; Right – Prostate identified posteriorly in boy (Images courtesy of Dinh et al.)

Video 6. Sagittal view of bladder

Formula

Figure 9. Bladder volume calculation per dimension

The bladder’s shape may appear more rounded when it is full or distended. Bladder volume may be assessed prior to urinary catheterization to avoid an unsuccessful catheterization. Many ultrasound machines also have software which can calculate estimated bladder volume based on the above measurements.

Manual Measurement (Figure 10)

  • In the transverse view, measure the width and depth.
  • In the sagittal view, measure the height from the apex to the base.

Figure 10. Bladder measurement example: Left – Transverse view with width (4.35 cm) and depth (3.65 cm); Right – Sagittal view with height (3.53 cm). Estimated volume = 39.2 mL

Estimated Bladder Capacity by Age

  • [Age of the child (yr) x 30] + 30 = bladder capacity in mL
  • In a toilet-trained child, a post-void volume of ≤20 mL is normal [1].

The scope of POCUS focuses on the detection of hydronephrosis which would necessitate further workup. Hydronephrosis may be secondary to various obstructive etiologies such as nephrolithiasis, masses, or anatomical anomalies.

Severity Grading

Hydronephrosis severity grading begins with dilation at the renal pelvis (grade 1 or pelviectasis), which can be present in normal individuals who have not urinated in some time. The greater the degree of hydronephrosis, the more the dilation extends outwards into the calyces and the renal cortex (Figures 11-15 and Videos 7-9).

Figure 11. Hydronephrosis grading scale (courtesy of Dinh et al.)

Hydronephrosis: Hydroureter

Figure 12. Hydroureter on ultrasound of the right kidney

Hydronephrosis: Mild

Figure 13. Mild hydronephrosis on ultrasound with only pelviectasis, or dilation of the renal pelvis (Image courtesy of Dr. Jim Tsung)

Video 7. Renal ultrasound showing pelviectasis

Hydronephrosis: Moderate

Figure 14. Moderate hydronephrosis showing dilation extending into the major/minor calyces (Image courtesy of POCUS atlas)

Video 8. Moderate hydronephrosis (full video from Figure 14)

Hydronephrosis: Severe

Figure 15. Severe hydronephrosis with dilation causing cortical thinning (Image courtesy of POCUS Atlas)

Video 9. Severe hydronephrosis with “bear claw” sign (full video from Figure 15)

Direct Visualization

Stones may be located anywhere along the urogenital tract. If directly visible, stones will appear as hyperechoic structures and may have acoustic shadowing (Figure 16).

Figure 16. Left – Hyperechoic renal stone with acoustic shadowing and associated moderate hydronephrosis; Right – Bladder stone with acoustic shadowing (images courtesy of Dr. James Tsung)

Video 11. Renal stone with acoustic shadowing and moderate hydronephrosis

Indirect Visualization

Direct visualization will not always be possible since stones are most commonly located in the ureters and may be obscured by bowel gas. Indirect signs of stones include hydronephrosis, twinkling artifact, and absence of ureteral jet [1, 4].

Twinkling artifact is a color Doppler finding that can help identify a stone that may not be directly visible in B-mode. It is generated from turbulent flow around a rough-edged structure (i.e, a stone). Color Doppler interrogation will produce a multi-colored high high-intensity structure behind the stone (Figure 17). The turbulent flow depicted can be seen even if the causative hyperechoic stone is not visible [1, 3].

Figure 17. Twinkling artifact in a patient with a right ureterovesciular junction stone (Image courtesy of Dr. James Tsung)

Video 12. Twinkling artifact from a renal stone

Caution

The scope of renal POCUS is primarily for identifying hydronephrosis, as supported by the literature (see below). However, incidental abnormalities may be noted, such as a renal cyst. Additional work-up is recommended per clinician judgment.

Renal cysts are thin-walled, smooth, localized, and anechoic areas that are round or oval in shape. They can occur as solitary lesions or multiple lesions often in the periphery of the kidney (Figures 18-19). They should not be confused with dilated medullary pyramids from hydronephrosis, which appear as branching and “interlinked” hypoechoic areas resembling a cauliflower. Cysts will have a more spherical shape and will not “communicate” with one another [5].

Figure 19. Single renal cyst without (left) and with (right) color Doppler flow to differentiate from vasculature (Images courtesy of Dr. Jeffrey Tutman)

Figure 20. Multiple renal cysts without (left) and with (right) color Doppler flow differentiating from vasculature  (Images courtesy of Dr. Jeffrey Tutman)

Caution

The scope of renal POCUS is primarily for identifying hydronephrosis, as supported by the literature (see below). However, incidental abnormalities may be noted, such as a masses. Additional work-up is recommended per clinician judgment.

Hyperechoic and heterogeneous lesions that distort or do not conform to typical renal architecture are concerning for renal masses. Wilms tumor is the most common renal malignancy in children with peak incidence between ages 1 and 5 years old. On ultrasound, it appears as an echogenic intrarenal mass that may have cystic areas from hemorrhage and necrosis (Figure 21) [4].

Figure 21. Wilms tumor in the right kidney without (left) and with (right) color Doppler flow (Images courtesy of Dr. Jeffrey Tutman)

Other potential neoplasms within or adjacent to the genitourinary system include but are not limited to neuroblastoma, rhabdoid tumor, rhabdomyosarcoma, renal cell carcinoma, and clear cell carcinoma [4, 6]. The most common malignant bladder mass is rhabdomyosarcoma, and the genitourinary tract is the second most common tumor site. It is usually large, nodular, well-defined, homogeneous, and slightly hypoechoic (Figure 13) [6].

Figure 22. Bladder rhabdomyosarcoma tumor without (left) and with (right) color Doppler flow (Images courtesy of Dr. Jeffrey Tutman)

  • Always scan both kidneys for comparison
  • Scan the bladder when evaluating the kidneys
  • Rib shadowing – attempt to maneuver around rib shadows by reangling the probe or moving up or down a rib space.
  • Bladder dimension calculations may be inaccurate if the calipers are not placed in the right orientations.
  • Large ovarian cysts may be mistaken for the bladder.
  • Because renal stones can be difficult to visualize directly, look for secondary signs such as hydronephrosis.
  • Because renal vasculature may be mistaken for hydronephrosis, use color Doppler to differentiate.
  • Renal cysts can be confused for hydronephrosis, and both warrant further imaging by Radiology.

Bladder volume estimation

Measuring bladder volume via POCUS in pediatric patients has been studied, demonstrating a benefit on Emergency Department workflow and length of stay (Table 1). For example, POCUS can confirm urine in the bladder, prior to catheterization in infants [7-8].

Author, Title, Journal, Publication YearStudy Type, Location, Time FrameN, AgesSummary
Milling et al., Use of ultrasonography to identify infants for whom urinary catheterization will be unsuccessful because of insufficient urine volume: validation of the urinary bladder index. Ann Emer Med, 2005 [7]Prospective, blinded, observational study performed in the pediatric ED, 3 month periodN=44, < 2 years of age
  • Created a bladder urinary index by multiplying the AP and transverse bladder diameters.
  • Determined the smallest bladder index that would result in successful urinary catheterization, which was defined as yielding at least 2 mL of urine.
  • The index achieved 100% sensitivity and 97% specificity.
Chen et al., Utility of bedside bladder ultrasound before urethral catheterization in young children. Pediatrics, 2005 [8]Prospective 2 -hase study, performed in the pediatric ED, 6 month periodN=136 for observation phase

N=112 for intervention phase

Ages 0-24 months

  • Observation Phase: The success rate of the first urethral catheterization attempt was calculated without preemptive bladder ultrasound
  • Intervention Phase: Bladder POCUS was performed, and catheterization was withheld until sufficient urine was present.
  • Successful catheterization rate during the observation phase was 72% overall, compared to 96% in the intervention phase.
Dessie et al., Point-of-Care Ultrasound Assessment of Bladder Fullness for Female Patients Awaiting Radiology-Performed Transabdominal Pelvic Ultrasound in a Pediatric Emergency Department: A Randomized Controlled Trial. Ann Emerg Med, 2018 [9]Randomized controlled trial, performed in a pediatric ED, 12 month periodN=120

8-18 years

  • To assess bladder fullness prior to transabdominal pelvic ultrasound, patients were randomized to subjective numerical scale versus bladder POCUS in addition to numerical scale.
  • Those in the bladder ultrasound arm completed their pelvic ultrasounds 51 minutes faster than the control group.
  • Success rate of pelvic ultrasound was 100% vs 84.7% in the control group.
Table 1. Pediatric bladder POCUS studies

Pediatric Hydronephrosis and Nephrolithiasis

Although adult studies (Table 2) have shown moderate diagnostic accuracy of POCUS in detecting hydronephrosis and nephrolithiasis, there is a dearth of POCUS-based renal studies in the pediatric literature . This has led to controversy whether to perform a renal ultrasound versus CT, even when the Radiology department performs the ultrasound.

  • Only 2 case series and 1 case report for POCUS-identified nephrolithiasis in children (Table 3)
  • No studies have aimed to determine sensitivity and specificity of POCUS for hydronephrosis in children in the context of renal colic.
Author, Title, Journal, Publication YearStudy Type, Location, Time FrameN, AgesSummary
Pathan et al., Emergency Physician Interpretation of Point-of-care Ultrasound for Identifying and Grading of Hydronephrosis in Renal Colic Compared With Consensus Interpretation by Emergency Radiologists, Acad Emerg Med, 2018 [10]Secondary analysis of images, obtained 2014-2015 from a large volume ED.N=651, Adults
  • Secondary analysis of ED physician POCUS images diagnosing hydronephrosis
  • Images were re-interpreted by radiologists to determine accuracy.
  • Sensitivity=85.7%, specificity=65.9%
  • CT was used as a reference standard when possible, yielding sensitivity=81.1% and specificity=59.4%.
Wong et al., The Accuracy and Prognostic Value of Point-of-care Ultrasound for Nephrolithiasis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med, 2018 [11]Systematic review & Meta-analysis, Multicenter, 2005 Through April 2016N=1,773, Adults
  • POCUS has modest diagnostic accuracy in adults for nephrolithiasis.
  • Moderate or greater hydronephrosis was highly specific for stones.
  • Detection of any hydronephrosis was suggestive of a stone >5 mm in size.
Kim et al., Usefulness of Protocolized Point-of-Care Ultrasonography for Patients with Acute Renal Colic Who Visited Emergency Department: A Randomized Controlled Study. Medicina, 2019 [12]Prospective randomized control trial in a tertiary care ED, March 2019-July 2019N=164, Adults
  • Evaluated POCUS protocol in managing patients with renal colic in the ED.
  • Patients were assigned to CT vs ultrasound group.
  • Length of stay was 62 min shorter and medical cost was lower in the ultrasound group with no difference in complications within 30 days.
Sibley et al., Point-of-care ultrasound for the detection of hydronephrosis in emergency department patients with suspected renal colic. Ultrasound J, 2020 [13]Prospective observational study in 2 Canadian academic EDs, April 2011 – July 2013N=413, Adults
  • Patients presenting with renal colic had an ED-performed POCUS.
  • The patients also had a CT or an ultrasound by Radiology as a reference standard.
  • For detecting hydronephrosis via POCUS, sensitivity=77.1% and specificity=71.8%.
Table 2. Adult POCUS studies on hydronephrosis and nephrolithiasis
Author, Title, Journal, Publication YearStudy Type, Location, Time FrameN, AgesSummary
Chandra et al., Point-of-care ultrasound in pediatric urolithiasis: an ED case series. Am J Emerg Med. 2015 [14]Case series in a pediatric ED, over a 2-year periodN=8

5-17 years

  • 8 cases of nephrolithiasis were identified with POCUS in patients presenting with renal colic.
  • All patients had confirmatory imaging in radiology.
  • Stones of 2 patients were visualized directly; others were identified by hydronephrosis, twinkling artifact, unilateral absence of ureteral jet, and/or a bladder bulge
Ng et al., Avoiding Computed Tomography Scans By Using Point-Of-Care Ultrasound When Evaluating Suspected Pediatric Renal Colic. Ultrasound in EM, 2015 [15]Retrospective case series in a pediatric ED, time frame not specifiedN=5

3-21 years

  • Hydronephrosis, ureteral jets, twinkling artifact, and the visualization of urinary tract stones were identified in patients with renal colic.
  • CT was avoided in all 5 patients.
Gillon et al., Diagnosis of Posterior Urethral Valves in an Infant Using Point-of-Care Ultrasound. Ped Emerg Care, 2021 [16]Case report in a tertiary pediatric ED, date not specified1, infant
  • Case report of 7-week old boy diagnosed with posterior urethral valves when the ED POCUS identified signs of bladder outlet obstruction. This included a thickened and distended bladder with bilateral hydroureter, severe bilateral hydronephrosis, and small perinephric fluid collections consistent with calyceal rupture.
Table 3. Pediatric POCUS studies on hydronephrosis and nephrolithiasis

Case POCUS

Using the curvilinear probe, you perform a POCUS on the bladder and both kidneys (Video 12).

Video 12. Bilateral renal ultrasound demonstrating twinkling artifact in the bladder and left-sided moderate hydronephrosis, indicative of a distal left ureteral stone (Video courtesy of Dr. Jim Tsung)

Case Resolution

Labs showed a slight leukocytosis with a serum WBC of 13 x109/L but no left shift and a normal creatinine. Urinalysis was positive for blood, RBC’s, and crystals but negative for glucose, ketones, leukocyte esterase, nitrites, WBC’s, squamous cells, and bacteria. The pain and vomiting were well-controlled with ketorolac and ondansetron, respectively. Urology was consulted and recommended medical management. The patient was discharged on tamsulosin and given urine-straining instructions.

Pediatrician Clinic Follow-Up

At her pediatrician clinic visit 2 weeks later, the patient had passed the stone and was asymptomatic.

Learn More…

References

  1. Paliwalla M, Park K. A practical guide to urinary tract ultrasound in a child: Pearls and pitfalls. Ultrasound. 2014 Nov;22(4):213-22. doi: 10.1177/1742271X14549795. Epub 2014 Nov 10. PMID: 27433222; PMCID: PMC4760558.
  2. Deschamps J, Dinh V, Ahn J, et al. Renal Ultrasound Made Easy: Step-By-Step Guide. POCUS101.com. [cited 2023 July 4].
  3. Sethi SK, Raina R, Koratala A, Rad AH, Vadhera A, Badeli H. Point-of-care ultrasound in pediatric nephrology. Pediatr Nephrol. 2023 Jun;38(6):1733-1751. doi: 10.1007/s00467-022-05729-5. Epub 2022 Sep 26. PMID: 36161524; PMCID: PMC9510186.
  4. Milla, Sarah; Lee, Edward; Buonomo, Carlo; Bramson, Robert T. Ultrasound Evaluation of Pediatric Abdominal Masses, Ultrasound Clinics, Volume 2, Issue 3, 2007, Pages 541-559.
  5. Koratala A, Alquadan KF. Parapelvic cysts mimicking hydronephrosis. Clin Case Rep. 2018 Feb 21;6(4):760-761. doi: 10.1002/ccr3.1431. PMID: 29636957; PMCID: PMC5889270.
  6. Shelmerdine SC, Lorenzo AJ, Gupta AA, Chavhan GB. Pearls and Pitfalls in Diagnosing Pediatric Urinary Bladder Masses. Radiographics. 2017 Oct;37(6):1872-1891. doi: 10.1148/rg.2017170031. PMID: 29019749.
  7. Milling TJ Jr, Van Amerongen R, Melville L, et al. Use of ultrasonography to identify infants for whom urinary catheterization will be unsuccessful because of insufficient urine volume: validation of the urinary bladder index. Ann Emerg Med. 2005;45(5):510-513. doi:10.1016/j.annemergmed.2004.11.010
  8. Chen L, Hsiao AL, Moore CL, Dziura JD, Santucci KA. Utility of bedside bladder ultrasound before urethral catheterization in young children. Pediatrics. 2005 Jan;115(1):108-11. doi: 10.1542/peds.2004-0738. PMID: 15629989.
  9. Dessie A, Steele D, Liu AR, Amanullah S, Constantine E. Point-of-Care Ultrasound Assessment of Bladder Fullness for Female Patients Awaiting Radiology-Performed Transabdominal Pelvic Ultrasound in a Pediatric Emergency Department: A Randomized Controlled Trial. Ann Emerg Med. 2018 Nov;72(5):571-580. doi: 10.1016/j.annemergmed.2018.04.010. Epub 2018 Jul 3. PMID: 29980460.
  10. Pathan SA, Mitra B, Mirza S, Momin U, Ahmed Z, Andraous LG, Shukla D, Shariff MY, Makki MM, George TT, Khan SS, Thomas SH, Cameron PA. Emergency Physician Interpretation of Point-of-care Ultrasound for Identifying and Grading of Hydronephrosis in Renal Colic Compared With Consensus Interpretation by Emergency Radiologists. Acad Emerg Med. 2018 Oct;25(10):1129-1137. doi: 10.1111/acem.13432. Epub 2018 May 28. PMID: 29663580.
  11. Wong C, Teitge B, Ross M, Young P, Robertson HL, Lang E. The Accuracy and Prognostic Value of Point-of-care Ultrasound for Nephrolithiasis in the Emergency Department: A Systematic Review and Meta-analysis. Acad Emerg Med. 2018 Jun;25(6):684-698. doi: 10.1111/acem.13388. Epub 2018 Mar 25. PMID: 29427476.
  12. Kim SG, Jo IJ, Kim T, et al. Usefulness of Protocolized Point-of-Care Ultrasonography for Patients with Acute Renal Colic Who Visited Emergency Department: A Randomized Controlled Study. Medicina (Kaunas). 2019 Oct 28;55(11):717. doi: 10.3390/medicina55110717. PMID: 31661942; PMCID: PMC6915595.
  13. Sibley S, Roth N, Scott C, et al. Point-of-care ultrasound for the detection of hydronephrosis in emergency department patients with suspected renal colic. Ultrasound J. 2020 Jun 8;12(1):31. doi: 10.1186/s13089-020-00178-3. PMID: 32507905; PMCID: PMC7276462.
  14. Chandra A, Zerzan J, Arroyo A, Levine M, Dickman E, Tessaro M. Point-of-care ultrasound in pediatric urolithiasis: an ED case series. Am J Emerg Med. 2015 Oct;33(10):1531-4. doi: 10.1016/j.ajem.2015.05.048. Epub 2015 Jun 23. PMID: 26321169.
  15. Ng C, Tsung JW. Avoiding Computed Tomography Scans By Using Point-Of-Care Ultrasound When Evaluating Suspected Pediatric Renal Colic. J Emerg Med. 2015 Aug;49(2):165-71. doi: 10.1016/j.jemermed.2015.01.017. Epub 2015 Apr 29. PMID: 25934378.
  16. Gillon JT, Cohen SG. Diagnosis of Posterior Urethral Valves in an Infant Using Point-of-Care Ultrasound. Pediatr Emerg Care. 2021 Aug 1;37(8):435-436. doi: 10.1097/PEC.0000000000002393. PMID: 34397679
By |2026-05-21T10:06:43-07:00Mar 7, 2024|Expert Peer Reviewed (Clinical), Genitourinary, Pediatrics, PEM POCUS, Renal|
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High sensitivity cardiac troponins for ED chest pain evaluation (2022 ACC pathway)

How do we best use high-sensitivity cardiac troponin (hs-cTn) to risk stratify patients with symptoms concerning for an acute myocardial infarction (AMI)? The 2022 American College of Cardiology (ACC) pathway provides timely guidance [1]. We help you translate this to your clinical practice, by illustrating with a case. Time to know your hs-cTn better.

Take-to-work points

  • When interpreting the hs-cTn, you can use either of the following pathways to optimize both accuracy and patient throughput:
    • European Society of Cardiology (ESC) 2020 0/1 hour or 0/2 hour pathway
    • High-Sensitivity Troponin in the Evaluation of Patients With Acute Coronary Syndrome (High-STEACS)
  • These clinical decision pathways utilizing hs-cTn are complicated to calculate on your own.
    • Encourage your ED to set up an algorithm that you can follow based on your laboratory’s assay.
    • Otherwise, apply a simplified approach. When patients present with <6 hours of symptoms, they are low risk if the 0- and 3-hour troponin levels are less than the 99th percentile upper reference limit (URL).
  • Low-risk patients do not routinely require stress testing in the ED.
  • Intermediate-risk patients may be further stratified based on recent stress testing or coronary angiogram findings plus a modified HEART or Emergency Department Assessment of Chest Pain (EDACS) score.

Applying the 2022 ACC guideline

Before delving into the specifics of the hs-cTn pathways, start with the ECG. The ACC 2022 pathway has a section dedicated to ECGs in ischemia [1], and FOAMcast has a great visual summary.

The 2022 ACC pathway [1] endorses clinical decision pathways that:

  • Use hs-cTn AND
  • Enable rapid rule-out using very low hs-cTn values (far below the 99th percentile) on arrival, or a very small change (delta) between 2 hs-cTn values.

Examples of such pathways include [2]:

  • The ESC 0/1 hour pathway, where hs-cTn is obtained on arrival, and if needed, 1 hour later.
  • The ESC 0/2 hour pathway, where hs-cTn is obtained on arrival, and if needed, 2 hours later.
  • The High STEACS pathway, where hs-cTn is obtained on arrival, and if needed, 3 hours later.

These clinical decision pathways take advantage of the diagnostic power of the delta hs-cTn value, resulting in higher sensitivity for AMI (99%) [3], more patients being able to be ruled-out for AMI [4], and more patients being discharged home with a shorter ED length of stay [5]. This contrasts traditional risk-stratification approaches, which compare hs-cTn values solely to the 99th percentile upper reference limit.

  • Note: Using the pathways and using a single hs-cTn result are not mutually exclusive concepts. Clinical decision pathways DO allow us to rule out AMI with a single hs-cTn value in some instances. An example is if the patient has a very low value (e.g., below limit of detection) AND the chest pain onset is >3 hours ago AND the ECG is non-ischemic.

Let’s apply the ESC 2020 0/1 hour pathway [2], with some modifications based on the 2022 ACC guidelines [1]:

high sensitivity cardiac troponin hs-cTn risk stratification

Figure 1. Stratification of patients for AMI based on high sensitivity troponin testing and the ESC 0/1 hour pathway (second hs-cTn drawn 1 hour after the initial hs-cTn test)

Notice how numbers are replaced with values A, B, C, D and E. That’s because these values are assay specific. You (or someone in your department) needs to know which assay your ED has, and use the appropriate values for that assay. Examples of cutoffs:

Figure 2: Assay-based cutoffs for different high sensitivity cardiac troponin tests from the 2022 ACC guideline [1] (Limit of quantification, LoQ)

One concept that cuts across all assays is the limit of quantification (LoQ). That’s the lowest hs-cTn value that can be reliably reported as a number for that assay. In the risk stratification pathway (figure 1), value E is often the LoQ, or an optimized threshold slightly above the LoQ.

Case #1

A 52-year-old woman presents with vague heaviness over the left side of the chest that does not radiate elsewhere. She does not recall clearly how it started, and it has been persistent for 5 hours. Its intensity does not change with walking or changes in posture. There are no associated symptoms such as diaphoresis, breathlessness, vomiting, fever, cough, or leg swelling.

She has hypertension and hyperlipidemia treated with lifestyle modification. She does not smoke. There is no family history of heart disease. She has no other recent illnesses or travel history.

On examination, her vital signs are normal. Heart sounds are dual with no murmurs and breath sounds are equal bilaterally. Pulses are well felt in all four limbs. There is no lower limb swelling or tenderness.

A 12-lead electrocardiogram (ECG) and chest x-ray (CXR) are unremarkable. The hs-cTn level on arrival is below the limit of quantification (LoQ).

Because the patient’s chest pain started >3 hours ago and she has a non-ischemic ECG, the initial hs-cTn is below LoQ already stratifies her as a LOW-RISK patient for AMI by the pathway. She does not need a repeat hs-cTn test. Caveat: Patients with known coronary artery disease might still have considerable risk for AMI even with this constellation of findings, requiring clinical judgment beyond this pathway [6].

Also do not forget that you still need to address other important potential causes of chest pain:

  • Aortic dissection appears unlikely, given the lack of suggestive features on history or physical examination. The onset was gradual with no radiation to the back or abdomen, and no features of distal ischemia such as neurological or pulse deficits. The CXR did not show any abnormalities consistent with a dissection.
  • Pulmonary embolism (PE) appears unlikely. She would be low risk by gestalt or structured scoring systems (Wells or revised Geneva), and a negative D-dimer would essentially rule out pulmonary embolism here. Note that the PE rule-out criteria do not help in this case, because she is >50 years old.

Thankfully, most patients will be low risk after walking through the above. What’s the disposition and follow-up plan for them? In short, less is more. As long as your clinical judgment concurs with a low-risk stratification, you should send the patient home with chest pain advice, return precautions, and recommendations to follow-up with their primary care provider within 30 days for optimal management of cardiovascular risk factors. You do not have to routinely order stress testing from the ED! This is endorsed in the 2022 ACC pathway [1] and the 2021 AHA chest pain guidelines [7].

The high-risk category

High-risk category hs-cTn values in the ESC 2020 0/1 hour pathway or high STEACS pathway come in 2 types:

  • A high absolute value
  • A high delta between two hs-cTn samples, which is suggestive of the rise or fall seen in AMI

Those values are assay- and pathway-specific, so you’ll need to find out more about your local assay. These in the high-risk category are usually admitted to the hospital to assess for AMI as well as other causes of troponin elevation.

What if you have a patient with intermediate findings?

Case #2

A 66-year-old man with hypertension, hyperlipidemia, diabetes mellitus, and chronic renal failure presents with poorly localized central chest discomfort while trying to sleep. It started 2 hours ago. The discomfort has a burning character, though he has never been diagnosed with reflux before.

His vital signs and physical exam are unremarkable other than an arteriovenous fistula on his left arm for hemodialysis. His ECG shows left ventricular hypertrophy.

The first hs-cTn results in the intermediate range on your assay-specific cutoff for the ESC 2020 pathway or high-STEACS pathway.

The first step is to repeat hs-cTn testing in 3-6 hours. Those with a significant change in hs-cTn (e.g., ≥ value D in the ESC 2020 pathway) will be diagnosed with acute myocardial infarction or acute myocardial injury (e.g., as seen in heart failure, arrhythmias, or sepsis).

How about those with no significant change? The ACC now endorses that these intermediate-risk patients can be considered for discharge with rapid follow-up, if 1 of these 4 criteria are met:

  1. Invasive or CT coronary angiogram <2 years ago without coronary plaque
  2. Stress test <1 year ago without ischemia
  3. Modified HEART score (where troponin is excluded) ≤3 [MDCalc] or EDACS<16 [MDCalc]
  4. Chronic elevations in hs-cTn similar to previously measured levels

Patients who do not meet these criteria above should get some form of additional evaluation such as non-invasive testing, such as a CT coronary angiogram, myocardial perfusion imaging, or stress echocardiography. If not, consider cardiology consultation or admission, or at least a shared decision-making with the patient for an expedited outpatient workup with the understanding that this group has a 30-day rate of death or MI ranging from 5% to 22% [1, 8, 9].

You repeat a hs-cTn 3 hours later and it remains unchanged. The patient has no previous stress testing or coronary angiogram, and he is not low risk by HEART or EDACS scoring.

You thus consult the cardiologist, who recommends to admit the patient to the hospital for further observation and evaluation.

Conclusion

  • Use the European Society of Cardiology (ESC) 2020 0/1 hour or 0/2 hour protocol, or the high-STEACS pathway when interpreting hs-cTn. They optimize both accuracy and patient throughput.
  • These clinical decision pathways utilizing hs-cTn are complicated to calculate on your own. Encourage your ED to set up an algorithm that you can follow based on your laboratory’s assay.
  • Otherwise, apply a simplified approach. When patients present with <6 hours of symptoms, they are low risk if the 0- and 3-hour troponin levels are less than the 99th percentile upper reference limit.
  • Low-risk patients do not routinely require stress testing in the ED.
  • Intermediate-risk patients may be further stratified based on recent stress testing, coronary angiogram findings, modified HEART score, EDACS score, or similar previous chronic hs-cTn elevations.

References

  1. Writing Committee, Kontos MC, de Lemos JA, et al. 2022 ACC Expert Consensus Decision Pathway on the Evaluation and Disposition of Acute Chest Pain in the Emergency Department: A Report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol. 2022;80(20):1925-1960. doi:10.1016/j.jacc.2022.08.750
  2. Collet JP, Thiele H, Barbato E, et al. 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation [published correction appears in Eur Heart J. 2021 May 14;42(19):1908] [published correction appears in Eur Heart J. 2021 May 14;42(19):1925] [published correction appears in Eur Heart J. 2021 May 13;:]. Eur Heart J. 2021;42(14):1289-1367. doi:10.1093/eurheartj/ehaa575
  3. Burgos LM, Trivi M, Costabel JP. Performance of the European Society of Cardiology 0/1-hour algorithm in the diagnosis of myocardial infarction with high-sensitivity cardiac troponin: Systematic review and meta-analysis [published online ahead of print, 2020 Jun 29]. Eur Heart J Acute Cardiovasc Care. 2020;2048872620935399. doi:10.1177/2048872620935399
  4. Badertscher P, Boeddinghaus J, Twerenbold R, et al. Direct Comparison of the 0/1h and 0/3h Algorithms for Early Rule-Out of Acute Myocardial Infarction. Circulation. 2018;137(23):2536-2538. doi:10.1161/CIRCULATIONAHA.118.034260
  5. Chew DP, Lambrakis K, Blyth A, et al. A Randomized Trial of a 1-Hour Troponin T Protocol in Suspected Acute Coronary Syndromes: The Rapid Assessment of Possible Acute Coronary Syndrome in the Emergency Department With High-Sensitivity Troponin T Study (RAPID-TnT) [published correction appears in Circulation. 2021 Jun 22;143(25):e1118]. Circulation. 2019;140(19):1543-1556. doi:10.1161/CIRCULATIONAHA.119.042891
  6. Ashburn NP, Snavely AC, O’Neill JC, et al. Performance of the European Society of Cardiology 0/1-Hour Algorithm With High-Sensitivity Cardiac Troponin T Among Patients With Known Coronary Artery Disease. JAMA Cardiol. 2023;8(4):347-356. doi:10.1001/jamacardio.2023.0031
  7. Gulati M, Levy PD, Mukherjee D, et al. 2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines [published correction appears in Circulation. 2021 Nov 30;144(22):e455]. Circulation. 2021;144(22):e368-e454. doi:10.1161/CIR.0000000000001029
  8. Mueller C, Giannitsis E, Christ M, et al. Multicenter Evaluation of a 0-Hour/1-Hour Algorithm in the Diagnosis of Myocardial Infarction With High-Sensitivity Cardiac Troponin T. Ann Emerg Med. 2016;68(1):76-87.e4. doi:10.1016/j.annemergmed.2015.11.013
  9. Twerenbold R, Neumann JT, Sörensen NA, et al. Prospective Validation of the 0/1-h Algorithm for Early Diagnosis of Myocardial Infarction. J Am Coll Cardiol. 2018;72(6):620-632. doi:10.1016/j.jacc.2018.05.040

Featured image adapted from Adobe Firefly

By |2024-02-08T22:47:41-08:00Feb 9, 2024|Cardiovascular, Expert Peer Reviewed (Clinical)|
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