Preliminary Diagnosis: Nephrolithiasis
I. What imaging technique is first-line for this diagnosis?
- Computed tomography (CT) scan without oral and without intravenous contrast
II. Describe the advantages and disadvantages of this technique for diagnosis of nephrolithiasis.
Advantages
- Able to locate an obstructive radiopaque renal, collecting system, and urinary bladder calculi
- Relatively quick imaging modalities that require minimal patient cooperation and are less susceptible to patient motion
- Able to detail secondary complications from an obstructing collecting system calculi (ie, calyceal or forniceal rupture, hydroureter or hydronephrosis, or pyelonephritis)
Disadvantages
- Exposure to ionizing radiation
- May not be able to localize nonradiopaque collecting system calculi
III. What are the contraindications for the first-line imaging technique?
- Contraindicated in pregnant patients especially within the first two trimesters
IV. What alternative imaging techniques are available?
- Ultrasound (grayscale)
- Radiography (plain film)
- For pregnant patients, ultrasound is the first-line imaging modality.
V. Describe the advantages and disadvantages of the alternative techniques for diagnosis of nephrolithiasis.
Ultrasound (Grayscale)
Advantages
- May be diagnostic for obstructive collecting system calculi
- May detail secondary signs of obstruction such as hydroureter and hydronephrosis
- Relatively inexpensive and portable imaging modality
- Does not utilize ionizing radiation
Disadvantages
- May not visualize the entire course of the ureter owing to overlying bowel gas and osseous structures
- Limited in detailing deep structures in obese patients
Plain Films
Advantages
- May be able to localize radiopaque calculi overlying the expected region of the kidneys, collecting system, and bladder
- Quick
- Inexpensive
- Far less radiation exposure with plain radiographs than with CT
Disadvantages
- Not very specific and has poor anatomic detail
- Nonradiopaque obstructive uropathy and secondary complications of obstruction are not well identified on plain radiographs.
VI. What are the contraindications for the alternative imaging techniques?
Ultrasound
- No significant contraindications exist to ultrasound.
Plain Films
- No significant contraindications. Some institutions may require consent for pregnant patients.
Copyright © 2017, 2013 Decision Support in Medicine, LLC. All rights reserved.
No sponsor or advertiser has participated in, approved or paid for the content provided by Decision Support in Medicine LLC. The Licensed Content is the property of and copyrighted by DSM.
