Diagnostic Ultrasound - Abdomen and Pelvis

Nephrocalcinosis
Diagnoses: Urinary Tract
TERMINOLOGY
• Medullary nephrocalcinosis (NC), cortical nephrocalcinosis
• Calcification of renal parenchyma
IMAGING
• Medullary NC: Generalized increased echogenicity of renal
pyramids with reversal of normal corticomedullary
differentiation± shadowing
• Cortical NC: Increased cortical echogenicity ±acoustic
shadowing
• Noncontrast CT is best imaging modality in adults
○ Exception: CT intravenous pyelogram (IVP) may be best
for medullary sponge kidney given high sensitivity for
stones and collecting tubule dilation
• US is 1st diagnostic imaging option in infants and children
with suspected nephrocalcinosis
TOP DIFFERENTIAL DIAGNOSES
• Renal calculus
KEY FACTS
• Emphysematous pyelonephritis
• Other causes of hyperechoic medulla: Metabolic and
protein deposition disorders, autosomal recessive
polycystic kidney disease
PATHOLOGY
• Most common causes of medullary NC are
hyperparathyroidism, renal tubular acidosis (RTA) type 1
(distal), and medullary sponge kidney
• Most common causes of cortical NC are acute cortical
necrosis, chronic glomerulonephritis, and oxalosis
• Medullary and cortical NC is rare and seen in oxalosis
DIAGNOSTIC CHECKLIST
• Medullary sponge kidney →asymmetrical, segmental, or
unilateral medullary NC
• Hyperparathyroidism and RTA type 1 → usually diffuse or
uniform calcification
• Oxalosis typically causes both medullary and cortical NC
• Nephrocalcinosis is often associated with urolithiasis
(Left) Graphic shows diffuse
calcification in renal the
pyramids, representing
medullary nephrocalcinosis.
(Right) Longitudinal US of the
left kidney shows echogenic
pyramids with reversal of the
normal corticomedullary
differentiation. Note the
medullary ring st of
hyperechoic rim outlining the
pyramid. Posterior acoustic
shadowing helps identify a
stone ſt.
(Left) Longitudinal US of the
right kidney shows
hyperechoic pyramids st with
reversal of the normal
corticomedullary
differentiation. Mild fullness
of the right renal collecting
system ſt is present. (Right)
Longitudinal color Doppler US
of the right kidney in the same
patient confirms the
hypoechoic spaces represents
caliectasis ſt.
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