Rib shadows can be overcome by angling probe between rib spaces
Depth should be optimized
Attempt visualization of proximal ureter
Labels are always very helpful
Diagnosis and Disposition
Septic Stone
Based on POCUS findings CT Stone Hunt Obtained
Left hydroureteronephrosis
Two obstructing Stones in Proximal Ureter
Measuring 8 and 4mm
Urology Consulted
Lvl 2 to OR for Ureteral Stent Placement
Hydronephrosis Grading
MILD - Dilation of Renal Pelvis
MODERATE - Dilation of Pelvis+Major Calyces
SEVERE - Dilation of Pelvis+Major Calyces +/- Cortical Thinning based on Chronicity
Recommend use of simplified grading system Mild-Moderate-Severe
No single consensus system exists, numerous exist
Most recognized is SFU grade (I – IV) which was developed in prenatal US and unnecessarily
complex for POCUS
Literature Review
Smith-Bindman R et al (2014): POCUS vs. Rads US vs. CT in 2759 patients
No difference between POCUS vs RUS; however less sensitive than CT
ED stay 1.3hr Shorter, no significant difference in 30d complications
Wong et al (2018) Systematic review of POCUS for renal colic
POCUS had modest sensitivity of 0.70 (95% CI 0.67-0.73), specificity of 0.75 (95%
CI 0.73-0.78) for any degree of hydronephrosis, performance better in setting of moderate
severity or higher
Taylor M et al. (2016) Ultrasonography for the prediction of urological surgical intervention
Presence of a stone or moderate-severe Hydro Sensitivity 0.97 (CI 0.89-1) for surgical
intervention specificity only 0.28
Presence of both Stone and Hydro increased Specificity to 0.91 (CI 0.88-0.94) with
+LR 2.94
Sibley et al (2020) with binary interpretation Hydro vs no Hydro trainees with 25
scans had no difference compared with more experienced providers
Take Away Points
1. While POCUS has moderate sensitivity/specificity for Proximal Stones, has excellent
sensitivity for need of Urologic Intervention
2. Applied in the correct patient may reduce Radiation and length of ER stay
3. Detection of moderate-severe hydro associated with need for intervention
4. Consider routine use of POCUS as a Screening Tool in low-risk patients
5. Maintain broad differential in ED bounce-backs and avoid anchoring
References
Sibley S, Roth N, Scott C, Rang L, White H, Sivilotti MLA, Bruder E. 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. Smith-Bindman R et
al.: Ultrasonography versus computed tomography for suspected nephrolithiasis. N Engl
J Med. 2014;371(12):1100-10. Taylor M, Woo MY, Pageau P, McInnes MD, Watterson J, Thompson J, Perry JJ. Ultrasonography
for the prediction of urological surgical intervention in patients with renal colic.
Emerg Med J. 2016 Feb;33(2):118-23. doi: 10.1136/emermed-2014-204524. Wong C 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;25(6):684-98
