Diagnostic ultrasound ( PDFDrive )

1760 PART V Pediatric Sonography
A
B
C
FIG. 51.30 Pelvic Varices. (A) Transverse sonogram in a
teenage girl with cirrhosis and ascites shows luid surrounding
the uterus and adnexal structures. (B) In a different patient with
cirrhosis and pelvic varices, a prominent vein (arrows) is seen
in the left adnexal region on transverse view. (C) Pulsed Doppler
waveform of paraovarian varix shunting blood toward the renal
veins or inferior vena cava.
Causes of Cirrhosis in Children
Hepatitis
Toxins accumulated in inherited metabolic diseases
Biliary atresia
Cystic ibrosis
Sonographically, these changes in hemodynamics are signaled
by decreasing diameter of the portal vein and its segmental
branches, to the point at which they are reduced to threadlike
structures. Flow velocity, when measurable, is reduced. Conversely,
branches of the hepatic artery (normally diicult to see in
children) may become visible with gray-scale sonography. Doppler
sonography mirrors the increased hepatic arterial caliber and
low seen angiographically. Doppler shits from segmental arteries
are increased compared with their portal venous neighbors.
Two hemodynamic mechanisms appear to operate in patients
with portal hypertension, especially in those with cirrhosis. he
backward-low theory explains portal hypertension by the
increased resistance to portal venous low caused by the intrahepatic
block described earlier. In response to stagnating
intrahepatic low, portosystemic collaterals form and drain blood
away from the liver, inally resulting in hepatofugal low in some
or all segmental branches and in the main portal vein, which is
easily demonstrated with Doppler sonography. Why does the
portal pressure remain elevated despite the presence of such a