ALiEM AIR Series | Renal Module (2023)

Welcome to the AIR Renal/GU Module! After carefully reviewing all relevant posts in the past 12 months from the top 50 sites of the Digital Impact Factor [1], the ALiEM AIR Team is proud to present the highest quality online content related to related to renal / GU emergencies in the Emergency Department. 6 blog posts met our standard of online excellence and were approved for residency training by the AIR Series Board. More specifically, we identified 3 AIR and 3 Honorable Mentions. We recommend programs give 3 hours of III credit for this module.

AIR Stamp of Approval and Honorable Mentions

In an effort to truly emphasize the highest quality posts, we have 2 subsets of recommended resources. The AIR stamp of approval is awarded only to posts scoring above a strict scoring cut-off of ≥30 points (out of 35 total), based on our scoring instrument. The other subset is for “Honorable Mention” posts. These posts have been flagged by and agreed upon by AIR Board members as worthwhile, accurate, unbiased, and appropriately referenced despite an average score.

Take the AIR Renal/GU Module at ALiEMU

Interested in taking the AIR quiz for fun or asynchronous (Individualized Interactive Instruction) credit? Please go to the above link. You will need to create a free, 1-time login account.

Highlighted Quality Posts: Renal / GU

EMCritAcute Kidney InjuryJosh FarkasMarch, 16, 2023AIR
EMCrit Hepatorenal SyndromeJosh FarkasApril 3, 2023AIR
EM DocsUrine trouble: approach to pediatric UTIJoe RaveraDecember 7, 2022HM
EM DocsTesticular TorsionBrit LongAugust 8, 2023HM
EM OttawaTesticular torsionAlex ViauJuly 27, 2023HM

(AIR = Approved Instructional Resource; HM = Honorable Mention)


If you have any questions or comments on the AIR series, or this AIR module, please contact us!



  1. Lin M, Phipps M, Chan TM, et al. Digital Impact Factor: A Quality Index for Educational Blogs and Podcasts in Emergency Medicine and Critical Care. Ann Emerg Med. 2023;82(1):55-65. doi:10.1016/j.annemergmed.2023.02.011, PMID 36967275


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


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
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)

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


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…


  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. [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

SAEM Clinical Images Series: Penile Lesion with a Poor Prognosis

A 49-year-old male presented to the emergency department of an academic hospital with the chief concern of penile pain. Prior medical history is notable for end-stage renal disease on hemodialysis three times per week, but the patient has not been dialyzed in the past four days, hypertension, insulin-dependent diabetes mellitus, heart failure with reduced ejection fraction (59% two months prior), seizure disorder, prior pulmonary embolism (eight months prior), a left nephrectomy seven months ago due to a gunshot wound, bradycardia status post permanent pacemaker, duodenal ulcer, and dry gangrene of the left foot. The patient was recently admitted to the hospital eight days prior to presentation for purulent urethral discharge where he received a course of topical antibiotics and was discharged. The patient stated he had 10/10 sharp penile pain since discharge from the hospital. He followed up with all “appropriate” appointments. He noticed that his penis started becoming discolored. He then noticed the pain start and grow in intensity without radiating anywhere else except the glans. He denies any discharge or pain with urination with 2-3 small volume voids daily but denies urine trapping.

GU: There is erythema, tenderness, and discoloration of the penile gland. There is no crepitus or swelling.

The rest of the physical exam is benign.

K: 6.5

Magnesium: 2.6

BUN: 70

Creatinine: 8.7

Alkaline phosphatase: 1562 (baseline 1069-1409)

Hemoglobin: 8.9 (at baseline)

WBC: 18.7 (monocyte predominance)

Calcinosis is characterized by the presence of precipitated calcium crystals in soft tissue. The condition is divided into 5 subtypes based on etiology and severity: dystrophic, metastatic, idiopathic, iatrogenic, and calciphylaxis (1). Dystrophic calcinosis cutis is caused by local trauma to the tissue, such as by repeated intravenous access, heel sticks, or other procedures, and is present in patients with normal calcium and phosphorus levels (1). Metastatic calcinosis cutis occurs in patients with underlying disorders of calcium or phosphorus metabolism (and therefore abnormal calcium and phosphorus levels) and can also be associated with calcium deposition in blood vessels, lungs, kidneys, and intestines (1). Iatrogenic calcinosis cutis is caused by the extravasation of intravenous calcium gluconate, calcium chloride, or fluids containing phosphorus (1). Idiopathic calcinosis cutis occurs in the absence of underlying causes like metabolic disorders or tissue damage. Calciphylaxis is the most serious subtype, defined as a vasculopathy of small and medium vessels that leads to ischemic necrosis.

Calciphylaxis is also known as uremic gangrene syndrome or calcific uremic arteriolopathy and is most often seen in patients with chronic renal failure, specifically those on hemodialysis. It is associated with extreme pain, infection, and a 60% to 80% mortality rate in the setting of few and frequently ineffective therapeutic options (2,3). Because of the rich vascular network of the penis, penile calciphylaxis is rare and is often associated with a poor prognosis having an overall mortality rate of 64% and an average of 2.5 months to death (4).

Take-Home Points

  • Calciphylaxis is the presence of calcium crystals in soft tissues and is often seen in hemodialysis patients.
  • Penile calciphylaxis is a rare finding that often portends a poor prognosis with a high mortality rate.

  • Nunley JR. Calcinosis cutis.
  • Vedvyas, C., Winterfield, L. S., & Vleugels, R. A. (2012). Calciphylaxis: a systematic review of existing and emerging therapies. Journal of the American Academy of Dermatology, 67(6), e253–e260.
  • Nigwekar SU, Kroshinsky D, Nazarian RM, Goverman J, Malhotra R, Jackson VA, Kamdar MM, Steele DJ, Thadhani RI. Calciphylaxis: risk factors, diagnosis, and treatment. Am J Kidney Dis. 2015 Jul;66(1):133-46. doi: 10.1053/j.ajkd.2015.01.034. Epub 2015 May 7. PMID: 25960299; PMCID: PMC4696752.
  • Yang TY, Wang TY, Chen M, Sun FJ, Chiu AW, Chen YH. Penile Calciphylaxis in a Patient with End-stage Renal Disease: A Case Report and Review of the Literature. Open Med (Wars). 2018 May 9;13:158-163. doi: 10.1515/med-2018-0025. PMID: 29756051; PMCID: PMC5941707.

SAEM Clinical Images Series: A Rare Cause of Recurrent UTI


A 52-year-old male presents to the Emergency Department with a chief complaint of right lower abdominal pain with urinary frequency and urgency over the past week. The pain radiates from his right groin with 10/10 severity at times. He reports multiple diagnoses of urinary tract infections over the last year requiring oral antibiotics. He claims intermittent constipation, denies any trauma, and is a truck driver by trade.

Vitals: T 97.7 °C; BP 138/75; HR 75; RR 16; O2 sat 96%

General: WDWN obese male, A/O x4, in mild distress

Abdomen: Soft, nondistended, normoactive bowel sounds, no organomegaly. A 5 cm moderately tender soft tissue bulge suggestive of a direct hernia is palpated in the right inguinal area and is reduceable.

Complete blood count (CBC): Within normal limits

Complete metabolic panel (CMP): Within normal limits

Urinalysis (UA):

  • Color: Cloudy, yellow
  • Blood: Trace
  • Leukocyte esterase: Positive
  • Nitrite: Positive
  • WBCs: 15-30 hpf
  • RBCs: 3-5 hpf
  • Bacteria: Moderate

This patient’s CT scans demonstrate an inguinal herniation of the urinary bladder, which occurs in less than 4% of all inguinal hernias. The clinical finding of a soft tissue mass in the groin in the setting of recurrent urinary tract infections should include urinary bladder herniation in the differential diagnosis.

Oral or parenteral antibiotics based on clinical presentation and prevalent sensitivities should be given to address urinary tract infections. Emergent or non-emergent (if reduceable) surgical consultation, usually by a urologist, is standard. Surgical reduction and repair techniques that utilize mesh versus non-mesh have been associated with a better prognosis with less recurrence.

Take-Home Points

  • Although rare, an inguinal herniation of the urinary bladder should be considered in males over 50 years old who have a herniation on physical exam and urinary complaints.
  • Risk factors include obesity, BPH, and male sex. This condition is diagnosed in very few women.
  • Computerized tomography is the usual imaging modality to diagnose a urinary bladder herniation.
  • Patients may be asymptomatic or have symptoms that may include inguinal pain or swelling, urinary retention, and acute renal failure.
  • Manual compression of hernia to void is pathognomonic for a urinary bladder herniation.

  • Branchu B, Renard Y, Larre S, Leon P. Diagnosis and treatment of inguinal hernia of the bladder: a systematic review of the past 10 years. Turk J Urol. 2018 Sep;44(5):384-388. doi: 10.5152/tud.2018.46417. Epub 2018 Sep 1. PMID: 30487042; PMCID: PMC6134980.
  • Papatheofani V, Beaumont K, Nuessler NC. Inguinal hernia with complete urinary bladder herniation: a case report and review of the literature. J Surg Case Rep. 2020 Jan 2;2020(1):rjz321. doi: 10.1093/jscr/rjz321. PMID: 31911827; PMCID: PMC6939942.

By |2023-10-06T13:25:23-07:00Oct 6, 2023|Genitourinary, SAEM Clinical Images|

Trick of Trade: Dual Foley catheter to control massive epistaxis

Massive epistaxis is considered a medical emergency that requires immediate attention. Symptoms of massive epistaxis include sudden and heavy bleeding from the nose, difficulty breathing, dizziness, and a rapid heartbeat. If left untreated, it can lead to significant blood loss, shock, airway obstruction, and even death. We report a case of a 50-year-old man with end stage renal disease with massive nasal bleeding from the left nostril, shortness of breath, and confusion.

Initial Management

After a rapid assessment, we inserted an anterior nasal pack, soaked in epinephrine, TXA, and an antibiotic-based lubricant. However, the bleeding continued from his nares and posterior oropharynx. We thus removed the anterior packing and instead inserted a Foley catheter into the posterior nasal space and inflated the balloon. Unfortunately, the bleeding still continued. Because he presumably had uremia-induced thrombasthenia (weak platelets), he received blood transfusions and IV TXA. And still — he continued bleeding heavily.

Trick of the Trade: Dual Catheter Technique

To provide optimal surface area coverage and tamponade effect of the posterior vessels, concurrent anterior packing is usually needed [1]. You can use commercial devices that have a dual balloon setup, but we did not have that available.

dual balloon for massive epistaxis

Illustration by Dr. Abdelhameed with patient-consented photo of dual balloon technique


  1. Insert the a 14-French Foley catheter into the nares with the patient’s mouth open (balloon 1). Stop when you see the tip of the catheter dangling in the posterior oropharynx.
  2. Inflate the balloon partially with 15-20 cc of air.
  3. Gently pull the catheter anteriorly until you feel resistance such that the balloon is snuggly positioned.
  4. If the bleeding still continues, insert a second Foley catheter until you meet resistance (balloon 2). Inflate this second balloon with 15 cc of air.

For our case, this dual catheter compression technique succeeded in halting the bleed.

Interested in Other Tricks of the Trade?


  1. Goralnick E. Posterior Epistaxis Nasal Packing. Medscape. Published Dec 9, 2020

Trick of Trade: Removal of Entrapped Metal Zipper

zipper entrapment injury

A young boy is brought to the pediatric emergency screaming at the top of his lungs by his parents. His penile skin is trapped in the zipper of his jeans. On a busy shift, you want a simple way to handle zipper injuries that minimizes pain, doesn’t require resource-intensive procedural sedation, and is quick.


The 4 most common types of zippers are nylon coil zip, plastic mold zip, metal zip, and invisible zip. Most of the techniques describing solutions on zipper entrapment in the medical literature are derived from case reports and case series. All revolve around understanding zipper anatomy and obtaining adequate exposure to assess how the skin is entrapped. The penile skin often is entrapped either in the sliding mechanism (also known as the endplate) or between the teeth of the zipper.

zipper anatomy

Figure 1. Anatomy of a zipper

Penile Entrapment Injury Management Techniques in Literature

Reported techniques for releasing zippers include [1, 2]:

  • Cut the sliding mechanism (aka the endplate) using metal cutters.
  • Use a flat screwdriver placed underneath the sliding mechanism and rotate it.
  • Use mineral oil for lubrication.
  • Use lateral compression technique to relieve the tension on the trapped skin.
  • Cut the zipper and pull the teeth apart.

All these techniques are associated with variable rates of success. Some of these techniques such as using metal cutters might lead to iatrogenic injuries.

The problem is that the child’s penile skin is entrapped within a metal zipper, where many recommended methods for zipper entrapment removal won’t work.

Trick of the Trade: Removing Metal Zippers

Materials Needed

  • Lidocaine gel
  • Blade or scissors


  1. The zipper should be separated from the pants as much as possible to minimize painful stretching or pulling of the penile skin.
  2. Apply lidocaine gel on the area of entrapment for 2-3 minutes.
  3. Identify the exposed teeth closest to slider and cut off the zipper at that level (blue dots) while avoiding penile skin (Figure 2).
  4. Gently advance the zipper body forward, pulling either the tab or the body itself, to disengage it from the teeth. You may need to add more lidocaine gel or other lubrication to facilitate this sliding motion.
  5. The remaining parts of the zipper can easily be disengaged from the skin (Figure 3).

metal zipper cut trick zipper entrapment

Figure 2. Cutting off the zipper between the teeth (blue dots) and advancing the zipper body (yellow arrow)

metal zipper entrapped free

Figure 3. Freed zipper body

Interested in Other Tricks of the Trade?


  1. Leslie SW, Sajjad H, Taylor RS. Penile Zipper and Ring Injuries. [Updated 2023 Mar 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.
  2. Tasian GE, Belfer RA. Genitourinary trauma. In: Fleisher and Ludwig’s Textbook of Pediatric Emergency Medicine, 7th ed, Shaw K, Bachur RG (Eds), Lippincott Williams & Wilkins, Philadelphia 2015.

SAEM Clinical Images Series: An 8-year-old Male with Dysuria


An 8-year-old Caucasian male with no significant past medical history presented to the pediatric emergency department (ED) with complaints of three days of abdominal pain and dysuria, accompanied by nausea, vomiting, and poor oral intake. The patient had previously presented to his pediatrician, where he was found to have microscopic hematuria and subsequently sent to the ED. Microscopic hematuria and increased abdominal pain in the ED prompted a point of care ultrasound (POCUS).

GI: Soft on palpation, normal bowel sounds, tender to palpation at midline below the umbilicus.

GU: No trauma or erythema of the penis.

Remaining exam wnl.

Urinalysis (UA): Yellow; Cloudy; Ketones: 15; Protein >=300; Leukocyte esterase: large; Nitrite: positive; WBC/HPF: Packed; RBC/HPF:51-100

Urine Culture: >100,000 staphylococcus CFU/mL

The most likely site of abnormality in this patient is the urethra. Image 1 shows massive bilateral hydronephrosis while image 2 shows hydroureter and bladder wall thickening. This presentation in a male, together with the lab findings suggestive of a UTI, should raise concerns for posterior urethral valves (PUV). PUV, a congenital obstruction of the urethra, is one of the most common causes of lower urinary tract obstruction in males. [1]

The next step in management for patients with probable PUV is a referral to a urologist for a voiding cystourethrogram (VCUG) and cystoscopy to assess for vesicoureteral reflux and valvular obstruction. Patients who are found to have PUV can then undergo incision and correction of the urethral valve. PUV typically presents in the newborn period in males with a poor urinary stream, urinary tract infections, and other voiding complaints and can be corrected with bladder catheterization or valvular ablation [1,2].

Take-Home Points

  • While rare, PUV should be considered in the differential for any pediatric patient presenting with urinary tract-related complaints, abdominal pain, and unexplained nausea or vomiting, particularly in school-aged males.
  • A school-aged male without an underlying diagnosis presenting to the hospital with a UTI should prompt clinicians to look for underlying predisposing conditions, such as PUV – an undertaking in which bedside ultrasound can be extremely useful.
  • Point of care ultrasound (POCUS) is a tool used in real time by emergency physicians to provide evidence for hydronephrosis, which can lead to the diagnosis of PUV.

  • Hodges SJ, Patel B, McLorie G, Atala A. Posterior urethral valves. ScientificWorldJournal. 2009 Oct 14;9:1119-26. doi: 10.1100/tsw.2009.127. PMID: 19838598; PMCID: PMC5823193.
  • Shields LBE, White JT, Mohamed AZ, Peppas DS, Rosenberg E. Delayed Presentation of Urethral Valves: A Diagnosis That Should Be Suspected Despite a Normal Prenatal Ultrasound. Glob Pediatr Health. 2020 Oct 15;7:2333794X20958918. doi: 10.1177/2333794X20958918. PMID: 33117862; PMCID: PMC7570289.

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