Case: 38 y/o female with a history of bilateral renal stones and recent lithotripsy for renal stone who presented with left flank pain and nausea. Symptoms were consistent with previous renal colic symptoms. Following lithotripsy, the patient had resolution of symptoms before flank pain and nausea returned 3 days ago. Vitals BP 142/97, Pulse 93, Temp 98.1 °F (36.7 °C) (Oral), Resp 18, SpO2 99%. The physical exam demonstrated left sided abdominal tenderness and left CVA tenderness. Bedside ultrasound findings below.
Answer: Ureteral stone at the left UPJ with mild-moderate left hydronephrosis
Ultrasound findings in nephrolithiasis
Hyperechoic foci with posterior acoustic shadowing
- Location of stone can help predict the probability of spontaneous passage of the stone. Stones in the distal ureter or UPJ are more likely to pass.
- Size of stone can help predict the probability of spontaneous passage as well
Hydronephrosis
- Greater degree of hydronephrosis reflects more obstruction of ureter and may indicate need for further imaging or procedural intervention
Twinkle Sign
- Intense alternating color signal behind calcifications and stones.
- Highly suggestive of a kidney stone (sensitivity 99.12%, specificity 90.91%, PPV 99.12%, NPV 90.91%)
Ureteral jets
- Representing maintained ureteral flow with color Doppler
- Some studies suggest it can predict spontaneous passage of distal ureteral stones
Conclusions:
Ultrasound can be used first-line for imaging to assess for renal stones, though may require follow-up imaging
Ultrasound may prevent repeated radiation exposure with CT in patients with known renal stones
Bedside US can allow for rapid diagnosis and treatment as well as faster discharge when assessing for renal stones
References:
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4. Gliga, M. L., Chirila, C. N., Podeanu, D. M., Imola, T., Voicu, S. L., Gliga, M. G., & Gliga, P. M. (2017). Twinkle, twinkle little stone: an artifact improves the ultrasound performance! Medical Ultrasonography, 19(3), 272-275. https://doi.org/10.11152/mu-984
3. Ongun S, Teken A, Yılmaz O, Süleyman S. Can Ureteral Jet Flow Measurement Predict Spontaneous Passage of Distal Ureteral Stones? Urol Int. 2018;101(2):156-160. doi: 10.1159/000490498. Epub 2018 Jun 27. PMID: 29949810.
4. 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.
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