Diagnostic ultrasound ( PDFDrive )

1318 PART IV Obstetric and Fetal Sonography
aneuploidy and fetal infections (e.g., CMV, 137 parvovirus B19, 138
and varicella 139 ). Calciications of the liver parenchyma should
be distinguished from peritoneal calciications that outline the
liver surface and peritoneal cavity, which can be secondary to
meconium peritonitis and may therefore be associated with
cystic ibrosis. Calciications associated with vascular insult
have also been reported, including thromboembolism of the
hepatic and portal veins. 140 Hepatic calciications may occur
with hepatic masses (discussed later). In a series of 21 pregnancies
with isolated hepatic calciications, there was one case of trisomy
21 and one case of parvovirus B19 infection; the rest of the
fetuses had normal outcomes. 138
Conditions Associated With Hepatic
Calciications
Normal variant—majority of cases when isolated or few
Aneuploidy
Fetal infection—CMV, parvovirus B19, varicella, herpes
simplex, toxoplasmosis
Hepatic vascular insult/ischemia
Hepatic mass
When hepatic calciications are visualized, it is important to
assess the number, size, and distribution of the calciications;
determine whether associated hepatic masses are present; document
normal low in the liver to rule out thrombosis; search for
other signs of fetal infection; and assess for any structural or
growth abnormalities. Genetic counseling and screening for cystic
ibrosis and fetal infections should be included in the investigation
of these cases.
Hepatic Cysts and Masses
he majority of hepatic masses are hypoechoic or cystic and
may include hepatic cysts (Fig. 38.19), hemangiomas (Fig. 38.20),
and abnormal myelopoiesis in fetuses with trisomy 21. 134 Less
commonly, solid echogenic masses may be identiied, which
may represent benign lesions such as hamartoma (which may
have a cystic or mixed cystic-solid appearance) and adenoma,
as well as malignant lesions as hepatoblastoma. Color low
Doppler ultrasound should be used to determine the vascularity
of the lesions. Vascular hepatic lesions include congenital
hemangiomas and hepatoblastomas, although it should be
emphasized that most hemangiomas are small and appear
avascular on color Doppler ultrasound. Such vascular lesions,
especially when of large size, may lead to high-output cardiac
failure and hydrops, and fetal anemia and thrombocytopenia
(Kasabach-Merritt sequence). 141-143 herefore these fetuses should
be followed for signs of hydrops and fetal anemia using middle
cerebral artery Doppler. 144-147
Gallbladder and Biliary System
he normal fetal gallbladder is an oblong, echolucent structure
in the anterior liver (Fig. 38.21, Video 38.9), generally located
45 degrees to the right of midline and inferior to the umbilical
vein. he gallbladder increases in size with gestation. 148 In multiple
series, visualization of the gallbladder was most common from
FIG. 38.19 Hepatic Cyst. Hepatic cyst (arrow) in sagittal view of
the abdomen.
20 to 32 weeks. 149,150 Enlarged gallbladder is associated with
fetal aneuploidy, but all reported fetuses also had other prenatally
visualized anomalies. 114
Nonvisualization of the Gallbladder
Nonvisualization of the gallbladder is associated with gallbladder
agenesis/atresia, cystic ibrosis, 151,152 aneuploidy, 151 and biliary
atresia. 149,153,154 Extrahepatic biliary atresia is a rare congenital
disorder, with an incidence of 0.6 in 10,000 live births according
to a population-based study. 155 It is the single leading cause for
liver transplantation during childhood and is commonly associated
with additional anomalies. 155,156 he diagnosis of extrahepatic
biliary atresia should be considered whenever the gallbladder
cannot be visualized. Additional indings may include a cyst in
the region of the hepatic hilum. 153 Bardin et al., in a study of 32
fetuses in which the gallbladder could not be visualized, reported
that amniotic levels of gamma-glutamyl transpeptidase (GGTP)
can assist in the prediction of pregnancy outcome. Of the 27
(84%) fetuses with normal GGTP levels, only 1 had an abnormal
karyotype, whereas 3 of the 5 fetuses with low GGTP were
diagnosed with extrahepatic biliary atresia. 154
In a series of 578 fetuses, Hertzberg et al. 149 demonstrated
the gallbladder between 12 and 40 weeks in 82.5% of cases, but
none of the fetuses with isolated nonvisualization of the gallbladder
had any adverse neonatal outcome. Blazer et al. 150 reported
on 29,749 consecutive women whose fetuses were imaged by
both transabdominal and transvaginal sonography at 14 to 16
weeks. he gallbladder could not be visualized in 34 (0.1%)
fetuses, and investigation that included amniocentesis and
screening for cystic ibrosis was ofered in all of these cases.
Additional abnormalities were identiied in 14 (41%) of these
fetuses. All 20 fetuses in which nonvisualization of the gallbladder
was an isolated inding had a normal karyotype and appeared
normal ater birth. In another series of 37 fetuses with nonvisualization
of the gallbladder, 5 (13.5%) were found to have