Clinical Indication

Flank pain, urinary retention, dysuria

Probe Selection

Curvilinear or Sector Probe

Additional Views and Measurements

  • Bladder measurements for the calculation of a Post-Void Residual (PVR) 
  • Use color doppler and comment on presence or absence of ureteral jets
  • Trace the ureter from the renal pelvis down the psoas muscle to evaluate for hydroureter


  • Mild Hydronephrosis (Grade 1)= Enlarged pelvis, no parenchymal compression, minimal disruption of the central sinus fat by fluid.
  • Moderate Hydronephrosis (Grade 2)= Enlargement of the pelvis with extension into the major and minor calyces in a branching fashion, but little to no parenchymal involvement. This is the “Bear Claw”view.
  • Severe Hydronpehrosis (Grade 3)= Thinning or obliteration of the parenchyma with massive dilatation of the pelvis and calyces and discontinuity of the sinus fat. 
  • In some patients you will not be able to view the entire kidney without a substantial rib shadow obscuring your view: 
    • You can use the anterior approach by placing the patient in the contralateral decubitus position and examining the kidney from the anterior abdomen just caudad to the costal margin. For example, place the patient in right lateral decubitus to view the left kidney.
    • Have the patient take a deep breath and you may be able to catch the optimal view as the kidney slides inferiorly.
    • If that doesn’t work, save your best view of the whole kidney in longitudinal and a view of the superior pole and one of the inferior pole.
    • Or you can switch to the Sector probe; with its smaller footprint it’s better able to view between ribs.
  • To calculate a PVR: in the transverse view measure the bladder left to right (Width), anterior to posterior (Height) and in the sagittal view, cephalad to caudad (Length). Then use the equation Length x Width x Height x 0.75 = PVR in cc’s (where 0.75 is a coefficient to correct for the trapezoidal shape of the bladder).
  • The literature is not in agreement with what constitutes an abnormal PVR. What is agreed upon is that ≤50 cc is normal and ≥200cc is abnormal regardless of age and sex. The PVR is expected to increase with age and parity, but between 50-200cc there isn’t a consensus. For example, a PVR of 100cc may be abnormal for a 25yo male with suspected cauda equina, but may be normal in a 70yo man.
  • Use Color Doppler or Power Doppler to evaluate for bladder jets. If you see one on the affected side in the setting of ureteral colic, then total obstruction is not present. Be patient when looking for bladder jets-this may take up to 20 minutes! If you encounter a cyst or mass-measure it!
  • If you encounter a mass: measure it in 3 dimensions and use color doppler to demonstrate the presence of absence of blood flow. 
  • If you suspect you see a renal stone use color doppler or power doppler to observe to “Twinkling” effect, which is an icicle-like artifact created by the echogenic stone.