Renal ultrasound

Pearls

• Renal cysts can sometimes be mistaken for hydronephrosis. Cysts are typically single and arise in the periphery of the kidney, but can be multiple as in polycystic kidney disease.
• Overhydrated, pregnant, or full-bladder patients may have mild hydronephrosis (bilaterally) without obstruction
• Underhydrated patients may not have hydronephrosis on initial renal scanning, despite obstruction
• Patient with multiple renal cysts may also have liver cysts (ultrasound liver)

Technique

1. 3.5-5 MHz probe
2. Right kidney
   1. Patient supine
   2. Probe in the right lower intercostal space in the midaxillary line
3. Left kidney
   1. Patient supine or right lateral decubitus
   2. Probe in the lower intercostal space on the posterior axillary line
      1. More cephalad and posterior than when visualizing the right kidney
4. Scan entire kidney (through liver)
   1. Longitudinal (long axis) and transverse (short axis) views
5. Scan the bladder

Questions

• Is there hydronephrosis?
  • Unilateral or bilateral?

• Is there fluid around the kidney?
• Is the bladder distended?
• Are stones seen?
• Is the aorta normal?

Findings

• Hydronephrosis
  • Mild: Distention of collecting system
  • Moderate: Dilation of collecting system, rounding of calyces
  • Severe: Dilated renal calyces and cortical thinning
    • “Bear claw” appearance
    • Obstructive uropathy

See Also

• Ultrasound (Main)
• Ultrasound: Aorta
• Acute Renal Failure

Source

• Sonoguide
• Cosby, K. (2006) Practical Guide to Emergency Ultrasound. Philadelphia, PA: Lippincott Williams & Wilkins pp. 237, 245-248