To assess

To assess the kidneys for diffuse and focal renal abnormalities, such as stones and masses; to assess the renal collecting systems for hydronephrosis; and to assess the urinary bladder for urinary retention, bladder wall hypertrophy, and intraluminal findings.

 

Limitations

None

 

Patient Preparation

Patient should be well hydrated.

The patient must hold their urine for at least 30 minutes before the trial begins.

 

Equipment Setup

Depending on the patient's body type, the curved transducer's 1-9 MHz frequency range provides the best possible penetration and anatomical resolution.

 

Common Pathology

• Increased creatinine or other findings of poor renal function

• Decreased urinary output; suspected hydronephrosis

• Flank pain; hematuria; suspected renal stones

• Urinary tract infection; pyelonephritis

• Conditions associated with focal renal abnormalities (examples: polycystic disease, tuberous sclerosis, von Hippel Lindau, etc)

• Follow up on known renal abnormalities

 

Scanning Technique

• Examine the right kidney from an anterolateral (in supine) or lateral approach in LLD position, with the liver as a sonographic window

• A posterolateral in an LLD or posterior in prone position may be required if the lower pole is not optimally seen (due to overlying bowel gas).

• Examine the left kidney from a posterolateral or direct lateral approach in the RLD position.

•  Ensure that both poles of the kidney are clearly seen. A posterior approach with the patient prone may be required if the lower pole is not completely seen (due to overlying bowel gas). An intercostal approach may be required for the upper pole.

• Asses the cortical echogenicity of the right kidney in comparison with the adjacent liver.

• Renal cortex, pelvis, and peri-renal region should all be assessed for abnormalities.

• Cine sweeps, both on transverse and long orientations, should be obtained through the entirety of each kidney.

• Color Doppler of the renal cortex (including upper, mid, and lower segments) allows for identification of segmental perfusion variations, particularly important for suspected pyelonephritis. For improved cortical perfusion, micro-Doppler Techniques:

o Philips - MicroFlow Imaging (MFI / MFI-D)

o GE - MicroVascular Imaging (MVI)

o Siemens - Slow Flow

• Color Doppler sweep through the kidney helps identify twinkling artifact seen with calculi.

• Color Doppler at the renal pelvis helps distinguish blood vessels from dilated collecting system (i.e. hydronephrosis).

• Focal renal abnormalities should be documented without and with size measurements and with color Doppler.

o Targeted cine sweeps are helpful in demonstrating subtle abnormalities

• If renal stones are suspected:

o Optimize grayscale image to demonstrate acoustical shadowing:

1.  Increase frequency range

2. Turn on Harmonics to reduce noise

3.  Turn off compound imaging (eg. SonoCT)

4.  Decrease speckle reduction (eg. XRes setting)

5.  Decrease dynamic range (increase compression)

6.  Or can use stone presets (eg. “Renal2” or “Renal*” presets) o Use and optimize color Doppler to demonstrate “twinkling” artifact

7.  Increase frequency range

8.  Decrease Doppler scale, but avoid aliasing of the intra-renal vessels by setting it too low.

9.  Minimizing noise/artifact (decrease color gain)

o Evaluate distal ureters and ureterovesicular junction with Color Doppler for twinkling artifacts from ureteral stones (best seen on transverse scanning) and for distal ureteral dilatation.

• Bladder lumen and wall abnormalities should be noted. Focal abnormalities should be documented without and with size measurements and with color Doppler.

If hydronephrosis is found:

o Evaluate distal ureters and the ureterovesical junction with Color Doppler for twinkling artifacts from stones (best seen on transverse scanning) and for distal ureteral dilatation.

o Within the bladder, obtain bilateral ureteral jets.

o With a full bladder, post-void imaging should be performed to document persistent hydronephrosis and bladder post-void residual

If pyelonephritis is suspected:

o Doppler evaluation of the renal cortex (including entire upper, mid, and lower segments) for perfusion variations. For improved cortical perfusion, use micro-Doppler techniques if available:

•  Philips - MicroFlow Imaging (MFI / MFI-D)

•  GE - MicroVascular Imaging (MVI)

•  Siemens - Slow Flow