Diagnostic Ultrasound - Abdomen and Pelvis

Enlarged Kidney
– Nonneoplastic causes: Dehydration and fever in
children; hypercoagulability and nephrotic syndrome
in adults
– Renal enlargement with ↓ echogenicity, renal vein
thrombus ± collaterals
– Unilateral > bilateral
○ Acute Renal Infarction
– Embolic or traumatic arterial occlusion
– Unilateral flank pain
– Normal or enlarged kidneys with wedge-shaped
defect on color Doppler
○ Acute Cortical Necrosis
– Caused by abruptio placentae, postpartum
hemorrhage, shock, sepsis, and toxins
– Results from microvascular thrombosis with cortical
ischemia
– Bilateral enlarged echogenic kidneys with hypoechoic
subcapsular rim
• Renal Abscess
○ Solitary or multiple thick-walled intrarenal cystic lesions
in the setting of infection
○ More common in patients with diabetes mellitus, drug
abuse, vesicoureteral reflux, renal calculi
• Pyonephrosis
○ Swollen obstructed kidney with debris or dependent
echoes in collecting system
• Perinephric Fluid Collections
○ May represent abscess, blood, urine, and lymph
○ May mimic large renal mass or compress the kidney
causing "page kidney"
• Renal Trauma
○ Perirenal and renal hematomas, renal fracture, contusion
Helpful Clues for Less Common Diagnoses
• HIV Nephropathy
○ Normal or enlarged kidneys
○ Typically increased echogenicity with decreased
corticomedullary differentiation
○ Later small
• Autosomal Dominant Polycystic Kidney Disease (ADPKD)
○ Usually presents in adulthood
○ Bilateral large kidneys with innumerable cysts of varying
sizes that distort normal renal architecture
• Multicystic Dysplastic Kidney (MDK)
○ Multiple noncommunicating renal cysts of varying size
with echogenic intervening parenchyma
○ Initially enlarged kidney, later atrophy
○ Association with contralateral renal disease common
• Horseshoe Kidney
○ Lower poles joined by isthmus of functioning renal tissue
or fibrous band
○ Lower in position with medially deviated lower poles
• Crossed Fused Renal Ectopia
○ Enlarged kidney with malrotation
○ Absence of contralateral kidney
Helpful Clues for Rare Diagnoses
• Autosomal Recessive Polycystic Kidney Disease (ARPKD)
○ Detected in utero or in infancy
○ Bilaterally enlarged kidneys with increased echogenicity
and multiple tiny cysts
• Renal Lymphoma
○ Focal or diffuse renal enlargement: Unilateral or bilateral
○ Infiltrative: Diffuse renal enlargement with disruption of
internal architecture
○ Perirenal soft tissue rind
• Renal Leukemia
○ Gross renal involvement uncommon
○ Symmetrically enlarged kidneys with distorted central
sinus and ↓ corticomedullary differentiation
• Xanthogranulomatous Pyelonephritis
○ Pelvicalyceal obstruction by stone, (usually staghorn)
○ Diffuse unilateral renal enlargement with echogenic
debris in dilated calyces and cortical thinning
○ Diabetes, recurrent urinary tract infections,
immunocompromise
• Renal Amyloidosis
○ Abnormal protein deposition in kidneys
• Renal Tuberculosis
○ Dilated calyces and granulomatous abscesses
Differential Diagnoses: Kidney
Hydronephrosis
Acute Pyelonephritis
(Left) Longitudinal ultrasound
of a markedly enlarged right
kidney with severe
hydronephrosis ſt,
hydroureter and cortical
thinning st in a patient with a
history of posterior urethral
valves and severe reflux. Renal
pelvis echoes could
represent infection, blood, or
cellular debris. (Right)
Longitudinal ultrasound in a
patient with acute
pyelonephritis and diabetes
shows an enlarged hypoechoic
right kidney st with loss of
corticomedullary
differentiation.
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