Diagnostic ultrasound ( PDFDrive )

CHAPTER 51 The Pediatric Liver and Spleen 1737
the dilated ducts. Abscesses complicating cholangitis are seen
as cavities with walls thicker than those of the ducts and illed
with heterogeneous material. Polycystic kidneys, when present,
are another clue to the diagnosis of Caroli disease; Caroli disease
and autosomal recessive polycystic kidney disease may occur
together because both are associated with mutation in the PKHD1
gene. 11
Spontaneous Rupture of Bile Duct
Rupture of the bile duct is rare. Rupture in newborns leads to
jaundice, abdominal distention, and substantial morbidity. Because
the site of rupture is usually the junction of the cystic duct and
CBD, it is believed that a developmental weakness at this site
leads to the rupture. he biliary system is undilated, but there
are ascites and loculated luid collections around the gallbladder.
Although the condition was previously treated surgically, the
recent trend is toward percutaneous drainage and conservative
management. 12
Paucity of Interlobular Bile Ducts and
Alagille Syndrome
Manifesting with chronic cholestasis, usually within the irst 3
months of life, ductal paucity and arteriohepatic dysplasia
(Alagille syndrome [ALGS]) are diagnosed histologically by
noting a reduced number of interlobular bile ducts compared
with the total number of portal areas. Because of cholestasis, the
gallbladder may be very small (disuse). he CBD is normal (Video
51.1). he liver is usually enlarged, especially the let lobe. Portal
hypertension ensues, with splenomegaly and esophageal varices.
In children with ALGS, paucity of bile ducts is associated with
a characteristic facies, pulmonary artery stenosis, butterly
vertebrae, segmentation anomalies, and, infrequently, renal
abnormalities (renal tubular acidosis). 13 ALGS is inherited as an
autosomal dominant disease with variable penetrance, most
commonly due to mutation in JAG1 (ALGS type 1), but in a
small proportion of cases mutation in NOTCH2 (ALGS
type 2). 14
Biliary Atresia
he incidence of biliary atresia varies from 1 in 8000 to 1 in
10,000 births. Boys and girls are equally afected. Biliary cirrhosis
occurs early, oten in the irst weeks ater birth. Biliary atresia
is characterized by absence or obliteration of the lumen of the
extrahepatic and intrahepatic bile ducts (Fig. 51.8). It is associated
with the polysplenia syndrome (biliary atresia, situs inversus,
polysplenia, symmetrical liver, interrupted IVC, preduodenal
portal vein) in about 20% of patients, 15 as well as with trisomy
17 or 18. Because the disease is extremely rare, and because the
pancreatic duct, which develops with the bile ducts, is normal
in afected children, biliary atresia likely develops ater the bile
ducts have formed. he etiology of biliary atresia is still unclear,
although there is evidence pointing to viral, toxic, and multiple
genetic factors. An in utero insult to the hepatobiliary system
may result in a progressive sclerosis of the extrahepatic and
intrahepatic bile ducts. In addition, certain drugs (e.g., carbamazepine)
have been associated with biliary atresia. 16
Jaundice classically develops gradually, 2 to 3 weeks ater birth.
he diagnosis is readily made if there are radiologic or sonographic
signs of the polysplenia syndrome (see Fig. 51.8C-G). Because
the low of bile is interrupted, the gallbladder is typically very
small (20%) or absent (80%). 15 Ater having the infant fast for
4 to 6 hours, a speciic search with a high-frequency transducer
will demonstrate a very small gallbladder (microgallbladder)
in about 20% of patients. When the gallbladder is visible, the
“ghost triad” appearance has been reported to help in making
the correct diagnosis of biliary atresia. 17 he ghost triad consists
of gallbladder length less than 1.9 cm, irregular or incomplete
mucosal lining, and irregular or lobular contour. he echogenic
ibrotic remnant of the CBD seen adjacent to the portal vein has
been called the triangular cord sign. he combination of a small
gallbladder, less than 1.5 cm in length, and the triangular cord
sign are very speciic for the diagnosis of biliary atresia. 5 Any
intrahepatic bile duct remnants may dilate and be visible at
sonography as bile duct dilation or small cysts. In addition, the
cholangitis that complicates biliary atresia may result in cystic
areas within the liver. 18
Surgical treatment creates communication between a loop of
jejunum (transposed to the liver ater a Roux-en-Y anastomosis)
and any patent bile “ductules” at the liver hilum. his is the
classic hepatoportoenterostomy described by Kasai in 1959. 19
Even if there is no mucosal contact between intestine and the
bile ducts, the procedure permits bile drainage, with complete
clinical remission in 30% and partial drainage in 30% of afected
children. he prognosis becomes much more guarded when the
Kasai procedure is delayed to more than 60 days ater birth. 20
Despite successful Kasai procedures, 75% of patients require
liver transplantation before age 20 years. 21 Biliary atresia remains
the most common reason for liver transplant in pediatric
patients.
Neonatal Hepatitis
Deined as an infection of the liver occurring before the age of
3 months, neonatal hepatitis is now considered an entity distinct
from toxic or metabolic diseases afecting the neonate. he
causative agent (bacterium, virus, or parasite) reaches the liver
through the placenta, via the vagina from infected maternal
secretions, or through catheters or blood transfusions. Transplacental
infection occurs most readily during the third trimester,
and syphilis, Toxoplasma, rubella, and cytomegalovirus (CMV)
are the most common agents 16 (Fig. 51.9, Video 51.2).
Neonatal bacterial hepatitis is usually secondary to upward
spread of organisms from the vagina, infecting endometrium,
placenta, and amniotic luid. In twin pregnancies, the fetus
nearest the cervix is more frequently afected. Listeria and
Escherichia coli are the usual organisms. During vaginal
delivery, direct contact with herpesvirus, CMV, human immunodeiciency
virus (HIV), and Listeria organisms may lead
to hepatitis. Blood transfusions may contain hepatitis virus B
or C, CMV, Epstein-Barr virus, and HIV. Infected umbilical
vein catheterization usually results in bacterial hepatitis or
abscesses. 16
With the exception of difuse hepatomegaly, there are no
speciic sonographic signs of hepatitis, unless abscesses (usually