Diagnostic ultrasound ( PDFDrive )

CHAPTER 51 The Pediatric Liver and Spleen 1735
Causes of Neonatal Jaundice
OBSTRUCTION OF BILE DUCTS
Choledochal cyst
Biliary atresia
Spontaneous perforation of the bile ducts
Paucity of interlobular bile ducts (Alagille syndrome)
HEPATOCELLULAR DAMAGE (CHOLESTASIS)
Hepatitis
Bacterial
Syphilis
Listeria
Staphylococcus
Viral
Hepatitis B
Hepatitis C
Cytomegalovirus
Human immunodeiciency virus
Rubella
Herpesvirus
Epstein-Barr virus
Parasitic
Toxoplasma
Systemic Diseases
Shock
Sepsis
Heart failure
Neonatal lupus
Histiocytosis
Hemolytic diseases
METABOLIC LIVER DISEASES
Galactosemia
Tyrosinemia
Fructose intolerance
α 1 -Antitrypsin deiciency
Cystic ibrosis
and anatomy of the obstruction are unclear. If sonography fails
to outline an anatomic abnormality, hepatobiliary scintigraphy
may deine patency of the CBD, unless hepatocyte damage is
extensive. If no radionuclide reaches the gut, liver biopsy is
typically performed. Both scintigraphy and the sonographic
search for the gallbladder are enhanced by the bile-stimulating
efect of phenobarbital administered for 3 to 5 days before the
test. 4 he triangular cord sign, an echogenic cone-shaped
density just cranial to the portal vein bifurcation on longitudinal
or transverse scans, is highly predictive of biliary atresia.
An absent or small gallbladder (<1.5 cm in length) coupled
with the triangular cord sign is even more speciic for the
diagnosis. 5
Choledochal Cyst
Dilation of varying lengths and severity of the CBD, termed
“choledochal cyst,” usually manifests as jaundice in infancy,
FIG. 51.5 Choledochal Cyst Classiication.
clinically mimicking neonatal hepatitis and biliary atresia (Fig.
51.5). Todani’s classiication describes ive types. 6 Type I, cylindrical
or saccular dilation of the common bile duct, is most
common (80%-90%) and is thought to be caused by an abnormal
insertion of the CBD into the pancreatic duct, forming a common
channel and facilitating relux of enzymes into the CBD, with
consequent inlammation. Because choledochal cysts have been
detected in 15-week gestational age fetuses, when amylase is not
yet present, and because surgically treated cysts in the newborn
period show minimal inlammation, there must be causative
factors (as yet unknown) other than the common-channel theory.
Two rare but well-documented causes of bile duct dilation
(choledochal cyst) in the newborn are localized atresia of the
CBD and multiple intestinal atresias in which the CBD empties
into a blind pouch of bowel. 7 A choledochal cyst manifesting
later in childhood may have a diferent pathogenesis. It is usually
complicated by cholangitis and classically causes abdominal pain,
obstructive jaundice, and fever. In some cases the cyst is palpable
as a mass.
Choledochal cyst type II consists of one or more diverticula
of the CBD (2% of cysts). Choledochocele (type III) is a dilation
of the intraduodenal part of the CBD (1%-5%). Multiple
intrahepatic and extrahepatic cysts make up type IV (10%),
sometimes subcategorized into types IVa and IVb, which has only
extrahepatic cysts. Caroli disease (type V) afects intrahepatic
bile ducts.
Sonographic screening of the jaundiced infant shows one or
several thin-walled cysts at the liver hilum or within the liver
(choledochal cyst type I; Fig. 51.6). he gallbladder is identiied
separately. Dilation of intrahepatic ducts, as well as stones, may
occur later as a result of bile stasis and cholangitis. Scintigraphy