Nephrolithiasis Imaging

See Also

Ureterolithiasis

Indications

Suspected Ureterolithiasis
1. See Ureterolithiasis for imaging decision strategy

Imaging
Noncontrast Helical CT Urogram (preferred, gold standard)

Indications
1. First-line in nonpregnant adult patients
2. Atypical presentations, age >55-75 years, esp. if no prior Ureteral Stones
3. Definitive study when instrumentation is required (e.g. infected Ureteral Stone)
Efficacy
1. Sensitivity: 95 to 100%
2. Specificity: 94 to 96%
3. Preferred over intravenous pyelogram
  1. Worster (2002) Ann Emerg Med 40:280-6 [PubMed]
Findings
1. Renal morphology
2. Ureteral Stone localization
3. Exclude alternative diagnosis (e.g. AAA, Diverticulitis, Appendicitis)
  1. IV Contrast-enhanced CT may be needed when differential diagnosis is broad
  2. IV Contrast-enhanced CT does not significantly reduce Test Sensitivity for Ureteral Stone
    1. Lei (2021) Am J Emerg Med 47:70-3 [PubMed]
Precautions
1. CT evaluation of Renal Colic has increased 10 fold since 1996
  1. Kocher (2007) Annals Emerg Med 58: 452-62 [PubMed]
2. Recurrent Ureterolithiasis results in numerous CT Abdomen scans and their associated risks
  1. See Cancer Risk due to Diagnostic Radiology
  2. Most Kidney Stones pass spontaneously, but CT findings of Nephrolithiasis result in a higher surgical intervention rate
3. Consider alternatives
  1. Consider Limited Ultrasound for Acute Renal Colic (see below)
  2. Consider close observation with reflex to CT for persistent symptoms
    1. If no contraindication such as Urinary Tract Infection, single Kidney
  3. Consider low dose CT
    1. Similar Test Sensitivity of 95% compared with full dose CT
    2. Radiation exposure at 10-20 fold less than with full dose CT
4. References
  1. Lin and Firestone in Herbert (2014) EM:Rap 14(7): 14-5

Imaging
Abdominal Ultrasound

See Limited Ultrasound for Acute Renal Colic
Indications
1. First-line study in pregnancy, children and in those with prior Ureteral Stones and typical presentation
2. Urolithiasis (considered primary evaluation in Europe)
3. Alternative diagnosis suspected (expanded protocol, often with provider performed Bedside Ultrasound)
  1. Cholecystitis
  2. Gynecologic process (e.g. ruptured Ovarian Cyst, Ovarian Torsion, Ectopic Pregnancy)
  3. Abdominal Aortic Aneurysm
Efficacy
1. Compares favorably to IVP and CT
2. Test Sensitivity: 64-93%
3. Test Specificity: 97-100%
4. Patlas (2001) Brit J Radiol 74:901-4 [PubMed]
5. Sinclair (1989) Ann Emerg Med 18(5): 556-9 [PubMed]
Findings
1. Hydronephrosis
2. Renal Stones (shadowing)
3. UVJ Stones (shadowing, asymmetric ureteral jets or color flow twinkling artifact)

Imaging
Abdominal XRay (KUB or Kidneys-Ureter-Bladder XRay)

Rarely used in modern U.S. practice, beyond following a CT-localized stone
Indications
1. History of prior radiopaque stones, esp. if following a stone localized by CT
Efficacy
1. Test Sensitivity: 45 to 59%
2. Test Specificity: 71 to 77%
Findings
1. Radiodense (radiopaque) stones
  1. Calcium Oxalate Stones
  2. Struvite Stones
2. Intermediate stone lucency
  1. Cystine Stones
3. Radiolucent stones (not visible on XRay)
  1. Uric Acid stones

Imaging
Intravenous Pyelogram (IVP)

Indications
1. Rarely used in modern U.S. practice
2. Nonpregnant patients where CT is not available
Efficacy
1. Sensitivity: 64 to 87%
2. Specificity: 92 to 94%
Findings
1. Functional renal and ureter study

References