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ABDOMINAL ULTRASOUND
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Separate facilities, such as a dedicated
children’s waiting area, are preferable and more
reassuring for the child.
The equipment should incorporate a range of
high-frequency (5–15 MHz) transducers with
small as well as conventional footprints. A small
curvilinear transducer is useful for most
abdominal work and a high-frequency linear
probe is essential for bowel sonography and
assessment of the acute abdomen. Transducers
with a dynamic frequency facility are an
excellent choice, as it is easy to switch to the
highest possible frequency without having to
change the transducer. The use of more than
one transducer, that is, both curvilinear and
linear, may be necessary, particularly in the
assessment of the acute abdomen.
A cine facility on the ultrasound machine is
invaluable, and cuts down scanning time.
Colour Doppler is essential in the assessment
of hepatobiliary problems and the examination
of the acute abdomen.
Generally speaking it is necessary to employ a
fast frame rate. (The smaller field of view
needed for children allows the line density to
remain high, maintaining adequate resolution.)
HEPATOBILIARY PATHOLOGY
Cystic fibrosis
Cystic fibrosis (CF) is a common, autosomal recessive
multisystem disease. The main organs affected
are the lungs, liver and pancreas. Accumulation of
mucus in the bronchi rapidly leads to respiratory
problems including infections, with a predisposition
to abscess formation with destruction of the terminal
bronchioles developing into bronchiectasis.
Pancreatic insufficiency, requiring enzyme supplements,
is a feature of CF, with gradual fatty
replacement and subsequent fibrosis of pancreatic
tissue, resulting in increased echogenicity of the
pancreatic parenchyma. The pancreas is generally
reduced in size. Cysts, calcification and ductal
dilatation may also be found. 1 Advances in the
management of pulmonary problems associated
with CF have led to longer survival and a subsequent
increase in the prevalence of chronic liver
disease. Annual ultrasound examination is recommended
as sonographic changes may be identified
in the absence of abnormality on biochemical
assessment. 2 The liver may be hyperechoic and
the texture becomes coarse and nodular as
fibrosis develops (Fig. 9.1). Increased periportal
echogenicity may be demonstrated. Eventually cirrhosis
develops, causing portal hypertension.
Assessment of the portal venous system with
colour and spectral Doppler is useful, providing a
baseline with which to compare progression of the
disease.
The gallbladder is small in up to one-third of
patients 3 (Fig. 9.1E). This microgallbladder measures
less than 3 × 1 × 1 cm after fasting and is filled
with mucus. Up to 10% of patients with CF may
have gallstones; cholecystitis and biliary strictures
may occur.
Neonatal cholestasis and biliary atresia
Neonatal hepatitis and biliary atresia are the most
common causes of neonatal cholestasis, presenting
around the age of 4 weeks with neonatal jaundice,
dark urine and pale stools. Early diagnosis of biliary
atresia and differentiation from hepatitis and other
causes of neonatal cholestasis is crucial to successful
treatment. The aetiology of biliary atresia
remains unclear but progressive inflammation,
destruction and fibrosis of the biliary tree occurs,
resulting in obliteration of all or part of the bile
ducts and gallbladder, with the subsequent development
of biliary cirrhosis. 4
The ultrasonic features of neonatal hepatitis and
biliary atresia overlap. The gallbladder is generally
small and thick-walled or absent in biliary atresia,
but may occasionally appear normal, 5 whereas in
hepatitis the gallbladder, although often normal in
size, may be difficult to visualize. The presence or
absence of a gallbladder is not a reliable sign of biliary
atresia. In cases of biliary atresia where only the
hepatic duct is atretic (that is, with a normal gallbladder
and common duct), the gallbladder can
appear normal in size and contract postprandially.
The liver may appear normal but in more severe
cases the liver parenchyma shows increased
echogenicity due to developing cirrhosis. The intraand
extrahepatic biliary tree is not dilated,
although occasionally small choledochal cysts or