II. Indications
- Suspected Ureterolithiasis
- See Ureterolithiasis for imaging decision strategy
III. Imaging: Noncontrast Helical CT Urogram (preferred, gold standard)
- Indications
- First-line in nonpregnant adult patients
- Atypical presentations, age >55-75 years, esp. if no prior Ureteral Stones
- Definitive study when instrumentation is required (e.g. infected Ureteral Stone)
- Efficacy
- Sensitivity: 95 to 100%
- Specificity: 94 to 96%
- Preferred over intravenous pyelogram
- Findings
- Renal morphology
- Ureteral Stone localization
- Exclude alternative diagnosis (e.g. AAA, Diverticulitis, Appendicitis)
- IV Contrast-enhanced CT may be needed when differential diagnosis is broad
- IV Contrast-enhanced CT does not significantly reduce Test Sensitivity for Ureteral Stone
- Precautions
- CT evaluation of Renal Colic has increased 10 fold since 1996
- Recurrent Ureterolithiasis results in numerous CT Abdomen scans and their associated risks
- See Cancer Risk due to Diagnostic Radiology
- Most Kidney Stones pass spontaneously, but CT findings of Nephrolithiasis result in a higher surgical intervention rate
- Consider alternatives
- Consider Limited Ultrasound for Acute Renal Colic (see below)
- Consider close observation with reflex to CT for persistent symptoms
- If no contraindication such as Urinary Tract Infection, single Kidney
- Consider low dose CT
- Similar Test Sensitivity of 95% compared with full dose CT
- Radiation exposure at 10-20 fold less than with full dose CT
- References
- Lin and Firestone in Herbert (2014) EM:Rap 14(7): 14-5
IV. Imaging: Abdominal Ultrasound
- See Limited Ultrasound for Acute Renal Colic
- Indications
- First-line study in pregnancy, children and in those with prior Ureteral Stones and typical presentation
- Urolithiasis (considered primary evaluation in Europe)
- Alternative diagnosis suspected (expanded protocol, often with provider performed Bedside Ultrasound)
- Cholecystitis
- Gynecologic process (e.g. ruptured Ovarian Cyst, Ovarian Torsion, Ectopic Pregnancy)
- Abdominal Aortic Aneurysm
- Efficacy
- Compares favorably to IVP and CT
- Test Sensitivity: 64-93%
- Test Specificity: 97-100%
- Patlas (2001) Brit J Radiol 74:901-4 [PubMed]
- Sinclair (1989) Ann Emerg Med 18(5): 556-9 [PubMed]
- Findings
- Hydronephrosis
- Renal Stones (shadowing)
- UVJ Stones (shadowing, asymmetric ureteral jets or color flow twinkling artifact)
V. Imaging: Abdominal XRay (KUB or Kidneys-Ureter-Bladder XRay)
- Rarely used in modern U.S. practice, beyond following a CT-localized stone
- Indications
- History of prior radiopaque stones, esp. if following a stone localized by CT
- Efficacy
- Test Sensitivity: 45 to 59%
- Test Specificity: 71 to 77%
- Findings
- Radiodense (radiopaque) stones
- Intermediate stone lucency
- Radiolucent stones (not visible on XRay)
- Uric Acid stones
VI. Imaging: Intravenous Pyelogram (IVP)
- Indications
- Rarely used in modern U.S. practice
- Nonpregnant patients where CT is not available
- Efficacy
- Sensitivity: 64 to 87%
- Specificity: 92 to 94%
- Findings
- Functional renal and ureter study