II. Indications

  1. Suspected Nephrolithiasis

III. Imaging: Noncontrast Helical CT Urogram (preferred, gold standard)

  1. Indications
    1. All nonpregnant patients
  2. 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]
  3. Findings
    1. Renal morphology
    2. Ureteral stone localization
  4. 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 Nephrolithiasis 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

IV. Imaging: Abdominal Ultrasound

  1. See Limited Ultrasound for Acute Renal Colic
  2. Indications
    1. Urolithiasis (considered primary evaluation in Europe)
    2. Pregnant patient and Children
    3. Cholecystitis suspected
    4. Gynecologic process suspected
  3. 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]
  4. Findings
    1. Hydronephrosis
    2. Renal Stones

V. Imaging: Abdominal XRay

  1. Indications
    1. History of prior radiopaque stones
  2. Efficacy
    1. Sensitivity: 45 to 59%
    2. Specificity: 71 to 77%
  3. 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

VI. Imaging: Intravenous Pyelogram (IVP)

  1. Indications
    1. Nonpregnant patients where CT is not available
  2. Efficacy
    1. Sensitivity: 64 to 87%
    2. Specificity: 92 to 94%
  3. Findings
    1. Functional renal and ureter study

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Ontology: Radiolucent calculus of urinary tract (C0582428)

Concepts Disease or Syndrome (T047)
SnomedCT 304543009
English Radiolucent calc urinary tract, Radiolucent calculus of urinary tract, Radiolucent calculus of urinary tract (disorder)
Spanish cálculo radiotransparente de vías urinarias (trastorno), cálculo radiotransparente de vías urinarias