Diagnostic ultrasound ( PDFDrive )

1804 PART V Pediatric Sonography
Color Doppler sonography is especially valuable in the search
for postbiopsy arteriovenous istulas (AVFs) and aneurysms. 107
Acute Renal Vein Thrombosis
Acute renal vein thrombosis may follow shock or occur as a
complication of the nephrotic syndrome, secondary to abnormal
coagulation, or in the presence of a nearby malignant mass, such
as Wilms tumor. In the neonate, thrombosis is usually associated
with dehydration, decreased renal perfusion and oxygenation,
and polycythemia. It is more prevalent in infants of diabetic
mothers. he clinical presentation includes hematuria, palpable
lank mass, proteinuria, and decreased renal function. Sonography
typically shows an enlarged kidney with altered parenchymal
echogenicity (Fig. 52.44). he normal corticomedullary diferentiation
is obliterated. Patchy areas of decreased and increased
echogenicity are secondary to edema and parenchymal hemorrhage.
Sonography may demonstrate echogenic thrombus within
the renal vein and inferior vena cava. hrombi are initiated in
small venules and propagate toward the hilum, so that renal
parenchymal abnormalities are oten present without clear
visualization of a thrombus. 89,108 In contrast, in the renal allograt,
thrombosis usually starts at the venous anastomosis.
Causes of Acute Renal Vein Thrombosis
Shock
Nephrotic syndrome
Coagulopathy
Adjacent tumors (e.g., Wilms tumor)
Neonatal dehydration, especially infants of diabetic
mothers
Doppler sonography may show decreased or absent low in
the renal veins, as well as a signiicantly increased RI in the
involved renal arteries. his decreased renal arterial diastolic
A
B
C
D
FIG. 52.44 Acute Renal Vein Thrombosis in Premature Infant. (A) Longitudinal image of the right lank demonstrates an edematous kidney
with echogenic parenchyma and decreased corticomedullary differentiation. (B) Longitudinal image of the inferior vena cava reveals a large intraluminal
clot (arrow). (C) and (D) Color and spectral Doppler images of the right renal artery reveal high-velocity arterial blood low with diastolic reversal
due to increased perivascular resistance secondary to intrarenal edema. No low is documented within the thrombosed main renal vein (arrow).