This describes the normal renal ultrasound protocol , normal examples and main indication to renal ultrasound .

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ULTRASOUND OF THE ADULT
KIDNEY
Dr Hisham Al Khatib
• A comprehensive examination of the renal
tracts should always include
• assessment of the urinary bladder and, in
males,the prostate.

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Coronal scan plane for the Right Kidney
Longitudinal: Normal Kidney
Scan plane transverse kidney
Transverse normal image

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ANATOMICAL VARIANTS
• In the 1st trimester, the developing kidneys
ascend in the foetal abdomen. If the progress is
hampered, this can result in:
– poorlAn ectopic kidney if it fails to reach the normal
position.
– Crossed fused ectopia (both on one side)
– Or a horseshoe kidney if the lower poles fuse.
• An interruption to the vascular supply to the
developing kidney will result in an atrophic, y
differentiated kidney.

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Common anatomical variants
• Atrophic small kidney
• Horseshoe kidney
• Ectopic kidney
• Duplex kidney
• Cross fused ectopia
• Unilateral renal agenesis
HORSESHOE KIDNEY
• Occurs when there is fusion of the
metanephros as they are pushed together
during their ascent from the sacral region.
• Almost always involves fusion of the lower
poles.
• There is an increase incidence of infection,
calculi and tumors in horseshoe kidneys.

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Horseshoe kidney: A transverse view across the midline showing the isthmus across
the aorta.
Horseshoe kidney: Longitudinal view of the horseshoe isthmus.

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A sagittal view of the isthmus of a horseshoe kidney.
ECTOPIC KIDNEY
• Also the result of abnormal or interrupted ascent
during embryology.
• The most common ectopic site is in the pelvis.
The kidney will lie obliquely in the ipsilateral iliac
fossa.
• Less commonly, a kidney may ascend to the other
side with 2 kidneys on one side of the abdomen.
This is called crossed-ectopia. This may result in a
single large fused kidney as shown below
(crossed-fused-ectopia)

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Cross fused ectopic kidney. The left kidney is fused to the lower pole of the right
kidney.
RENAL ULTRASOUND PROTOCOL

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ROLE OF ULTRASOUND
• To identify the cause of:
– Flank pain
– Haematuria (frank or microscopic)
– Follow-up of previously identified pathology
– Classification of a mass (Solid V's cystic)
– Post surgical complications
– Guidance of aspiration, biopsy or intervention
– Post injury
LIMITATIONS
• The mid to distal ureter is generally obscured
by bowel gas.
• Small lesions at the upper pole of the kidney
may be difficult to see due to refractive edge
shadowing. This can be overcome with
thorough scanning technique.
•

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EQUIPMENT SELECTION
• Highest frequency curved linear array probe
possible. Start with 7MHz and work down to 2
or 3 for larger patients. Assess the depth of
penetration required and adapt. Paediatric
and thin patients should be scanned with a
7MHz. Good colour / power / Doppler
capabilities when assessing vessels or
vascularity of a structure.
PATIENT POSITION
• Begin with the patient supine. Each kidney
may also need to be examined in the
decubitus position. Raise the ipsilateral arm
above the patient's head

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TECHNIQUE
• A comprehensive examination of the renal tracts
should always include assessment of the urinary
bladder and, in males,the prostate.
Scan longitudinally right subcostally. Visualise the
kidney inferior to the right lobe of the liver (RT), or
spleen (LT). Place the probe between iliac crest and the
lower costal margin to examine in the coronal plane.
Ensure the kidney is thoroughly examined from edge to
edge. Rotate into transverse. Scan from beyond the
superior margin to inferior. Document the normal
anatomy and any pathology found, including
measurements and vascularity if indicated.
WHAT TO CHECK
• Kidney size (should not be >1cm difference
between sides)
• Cortical thickness(not <10mm)
• Cortico-medullary differentiation
• Cortex at least as hypoechoic as the liver
• Pyramids slightly hypoechoic relative to the
cortex
• No hydronephrosis
• Renal scarring(beware mistaking prominant
lobulations as scars)

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COMMON PATHOLOGY
• Calculus
• Renal cyst
– Cortical
– Parapelvic
• Angiomyolipma
• Renal cell carcinoma
• Transitional cell carcinoma
• Hydronephrosis
• Medullary sponge kidney
• Polycystic kidney disease
•
BASIC IMAGING
• A renal series should include the following minimum
images;
• Both kidneys with length measurements
• Right kidney long with liver for comparison
• Both kidneys longitudinal medial and lateral
• Both kidneys transverse
– sup
– mid
– inf
• Left kidney long with spleen for comparison
• Document the normal anatomy. Any pathology found in 2
planes, including measurements and any vascularity.