Diagnostic ultrasound ( PDFDrive )

1756 PART V Pediatric Sonography
when measured at the same sites in the same person. 70 Arterial
signals within the liver may be diicult to ind ater a meal. his
is particularly disturbing in the patient who has received a liver
transplant, in whom a false diagnosis of thrombosis may be
considered.
Portal Venous Hypertension
Portal venous hypertension is a pathologic condition characterized
by increased pressure in the portal vein or one of its tributaries.
he normal pressure in the portal vein is between 5 and
10 mm Hg. When the pressure in the portal vein is more than
5 mm Hg above IVC pressure, portal hypertension is present.
he many sequelae of portal hypertension include splenomegaly,
collateral vein formation, and a thickened lesser omentum.
In children the lesser omentum is observed between the let lobe
of the liver and the aorta on sagittal images. Lesser omentum
thickness should not exceed the diameter of the aorta 70,71 (Fig.
51.27). In portal hypertension it is thickened by lymphatic stasis
and an engorged let gastric vein. Morphologic changes of the
liver architecture are usually present as well.
An increased caliber of the portal vein and a lack of variation
in the caliber of the splenic and mesenteric veins have been
described in portal hypertension in adults. he accuracy of these
indings in the assessment of portal hypertension in children
A
B
C
FIG. 51.27 Lesser Omentum. (A) Sagittal left
paramedian sonogram of a 12-year-old boy shows
normal omentum between the left lobe of the liver
and the aorta (arrows) and smaller than the aorta (A).
D, Diaphragm; e, esophagus. (B) Thickened lesser
omentum (arrows) by a tortuous, dilated left gastric
vein in cirrhosis. (C) Abnormal left gastric vein. Color
Doppler image shows low signals toward the esophagus
(blue).