Diagnostic ultrasound ( PDFDrive )

CHAPTER 38 The Fetal Gastrointestinal Tract and Abdominal Wall 1319
A
B
FIG. 38.20 Hepatic Mass. (A) Hepatic hemangioma (arrow) in 18-week fetus. (B) Coronal ultrasound at 34 weeks shows a large, heterogenous
echogenic mass (arrowheads) replacing the entire right lobe of the liver, thought to be an infantile hemangioendothelioma. The infant was
delivered at 38 weeks because of signs of cardiac decompensation but did well with spontaneous tumor involution over several months. (A with
permission from McNamara A, Levine D. Intraabdominal fetal echogenic masses: a practical guide to diagnosis and management. Radiographics.
2005;25[3]:633-645. 32 )
the amniotic luid may be ofered as well. When these investigations
are negative, fetal outcome is expected to be normal in the
majority of cases. In many of these cases, the gallbladder will
become apparent later in pregnancy or ater delivery. 154 In the
remainder of cases, the underlying cause may be agenesis of the
gallbladder, which may be considered as an anatomic variant.
Fetal Gallstones
Echodensities in the fetal gallbladder can represent either sludge
or gallstones and are most commonly seen in the third
trimester. 157-159 Gallstones may produce acoustic shadowing (Fig.
38.22). In most cases, postnatal resolution occurs, and children
are asymptomatic.
FIG. 38.21 Normal Gallbladder. Transverse color Doppler image
at 35 weeks shows the normal gallbladder (GB) as an oval, anechoic
structure in the right upper quadrant. The umbilical vein (UV) enters the
portal venous system anterior to the aorta and inferior vena cava, which
are seen anterior to the spine (Sp). See also Video 38.9.
cystic ibrosis, but in all of these cases echogenic bowel was
present as well. 152
hus nonvisualization of the gallbladder should be followed
by a detailed scan for additional structural abnormalities, sot
markers for aneuploidy, and other markers of cystic ibrosis such
as echogenic bowel. Screening for cystic ibrosis and amniocentesis
for karyotype and assessment of the level of liver enzymes in
Choledochal Cyst
Choledochal cysts are rare congenital cystic dilatations of the
biliary tree and are associated with biliary atresia and hepatic
ibrosis 160 (Fig. 38.23). he most common form involves a segment
or all of the extrahepatic common bile duct; however, they may
also present as diverticular outpouching of the extrahepatic duct
or involve the intrahepatic ducts (Caroli disease). Cystic lesions
of the biliary tree in utero may be anechoic or may contain
echogenic debris. Although these lesions can be due to choledochal
cyst, a cyst in the right upper quadrant can also be due to a rare
bilobed gallbladder. he main diferential diagnosis is extrahepatic
biliary atresia. In most cases choledochal cysts are resected ater
birth, given the risk of cholangitis, ibrosis, and potential
malignancy.
Pancreas
Visualization of the pancreas is oten not possible at the time of
the second-trimester anatomy scan. he pancreas may be seen