Diagnostic Ultrasound - Abdomen and Pelvis

Small Kidney
○ Pseudotumors from adjacent hypertrophy
• Chronic Renal Artery Stenosis
○ Mostly atherosclerosis affects main, interlobar, or
interlobular renal arteries or arterioles
○ Progressive generalized reduction in kidney size caused
by ischemia
○ Produces renal atrophy or collateralization
○ Smooth contour
• Chronic Renal Infarction
○ Renal atrophy after acute renal infarction caused by
embolism or thrombosis
○ Atrophy may be focal (segmental) or global
○ Parenchymal loss depends on distribution of occluded
artery
○ Infarcted area may be contracted, producing renal scar
○ More common in transplanted than native kidneys
• Chronic Vascular Injury
○ Sequela of vasculitides such as polyarteritis nodosa or
ischemia from fibromuscular dysplasia
○ End result of nonspecific small echogenic kidneys
• Post-Traumatic Renal Atrophy
○ Caused by segmental renal infarction due to renal artery
thrombosis after blunt renal trauma or after
embolization for bleeding
○ Contracted kidney + irregular outline
○ Collateralization may be demonstrated
• Following Acute Cortical Necrosis or Acute Tubular
Necrosis
○ May be associated with cortical or medullary calcification
• Post Chemotherapy
○ Scarring after therapy for renal lymphoma, leukemia, or
metastases
Helpful Clues for Rare Diagnoses
• Chronic Radiation Nephropathy
○ Occurs after renal irradiation for bone marrow
transplantation
○ Begins months to years after irradiation
○ Areas of diminished perfusion may be seen
○ Small kidneys with increased renal echogenicity
• Chronic Nephritis (Alport Syndrome)
○ Chronic hereditary nephritis
○ Small kidneys + smooth renal outline
○ ↑ cortical echogenicity due to cortical nephrocalcinosis
• Renal Cystic Dysplasia
○ May be bilateral
○ Associated with posterior urethral valve, renal
duplication, crossed-fused ectopia, horseshoe and pelvic
kidneys
○ Unilateral small kidney with increased echogenicity and
small cortical cysts
• Medullary Cystic Disease Complex
○ Inherited cystic renal disease
○ Progressive tubular atrophy with glomerulosclerosis
○ Echogenic kidneys with progressive decrease in size
○ Multiple small medullary cysts
• Tuberculous Autonephrectomy
○ Calcified caseous pyonephrosis with UPJ fibrosis
○ Shrunken kidney + extensive calcification
○ Dilated calyces
• Renal Hypoplasia
○ At least 50% smaller than normal
○ Has fewer calyces and papillae
○ Renal function normal for its size
○ Usually unilateral
○ Differentiation from obstruction, chronic pyelonephritis,
and ischemia difficult
• Supernumerary Kidney
○ Extremely rare, hypoplastic 3rd kidney
○ Connected to dominant kidney either completely or by
loose areolar connective tissue
○ Most are caudal to orthotopic kidney
• Chronic Lead Poisoning
○ Bilateral small kidneys
○ Indistinguishable sonographically from other causes of
renal atrophy
○ Blood level of lead useful for diagnosis
Differential Diagnoses: Kidney
Chronic Diabetic Nephropathy
Chronic Glomerulonephritis
(Left) Longitudinal ultrasound
of the right kidney in endstage
renal disease and
diabetes. There is diffuse
cortical thinning ſt with
increased echogenicity and
preserved corticomedullary
differentiation st. (Right)
Longitudinal ultrasound of the
right kidney in end-stage renal
disease and cirrhosis. The
kidney ſt is small (8 cm) with
increased echogenicity and
loss of corticomedullary
differentiation. Ascites and
nodular liver contour st is
present.
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