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ABDOMINAL ULTRASOUND
ipsilateral renal vein and IVC and Doppler sonography
shows reduced or absent blood flow in the renal
vein and loss of the normal variation in the renal
vein waveform. Arterial flow is also decreased. On
follow-up the kidney may completely recover due to
the development of collateral blood flow or early
recanalization of the renal vein, but in severe cases
the kidney may atrophy and calcify.
ADRENAL GLANDS
Normal appearances
In utero and postnatally, the adrenal glands are
large, about one-third the size of the kidney, and
composed mainly of the bulky, hypoechoic fetal
cortex which makes up about 80% of the gland.
The neonatal adrenal glands are easily demonstrated
on ultrasound. The bulky fetal cortex is
sonographically apparent as a thick hypoechoic
layer surrounding the thinner, hyperechoic adrenal
medulla (Fig. 9.13A). The fetal cortex surrounds
the smaller, permanent cortex and
gradually starts to involute after birth. By the age
of 2–4 months, the adrenal glands have attained
their normal adult configuration of the thin,
hypoechoic cortex with a tiny layer of hyperechoic
adrenal medulla within.
Neuroblastoma
The neuroblastoma is a malignant tumour arising
in the sympathetic chain, most commonly the
adrenal medulla. The majority of neuroblastomas
present before the age of 4 years with a palpable
abdominal mass, and many already have metastases
at the time of presentation to the liver, bone
marrow, skin or lymph nodes. Table 9.4 lists the
most frequent abdominal tumours occurring in
childhood.
The tumour is usually large on presentation,
displacing the kidney downwards and laterally. In
some cases it may invade the adjacent kidney,
becoming difficult to distinguish from a Wilms’
tumour. Neuroblastoma is predominantly solid on
ultrasound, having a heterogeneous texture and
frequently containing calcification. The tumour
margins are ill-defined and infiltrate the surrounding
organs and tissues, crossing the midline and
encasing vascular structures: it may be difficult to
differentiate from lymphadenopathy (Fig. 9.13B,
C and D). Nodes tend to surround and elevate the
aorta and IVC.
MRI and CT are used for staging, particularly in
assessing retroperitoneal spread. 22 Bone scintigraphy
and MIBG scans are also useful in demonstrating
metastases.
Adrenal haemorrhage
After birth, the bulky fetal cortex normally involutes.
Adrenal haemorrhage occurs in the neonate
as a result of trauma to the vulnerable fetal cortex
during delivery or in association with perinatal
asphyxia. Haemorrhage may occur in up to 2% of
births. 23 This may be uni- or bilateral and may
cause a palpable mass and abdominal pain.
Ultrasound can be used to follow the resolution of
the haemorrhage over a period of weeks; in the initial
stages of haemorrhage the adrenal mass is
hyperechoic, gradually liquefying into a welldefined
mass of mixed echo pattern and becoming
cystic (Fig. 9.13 E, F). This may completely resolve
over a period of some weeks leaving a normal adrenal
gland or the gland may become atrophic and
calcify. In rare cases an adrenal haemorrhage may
progress to an abscess. 24
Adrenal calcification
Calcification of the gland in babies and infants is
usually the result of previous infection or haemorrhage.
Adrenal abscess cavities may calcify after
successful treatment. Gross calcification in
bilateral adrenal glands in association with
hepatosplenomegaly in the infant indicates the
likely diagnosis of Wolman’s disease, an inborn
error of lipid metabolism that is invariably fatal.
GASTROINTESTINAL TRACT
Bowel ultrasound in paediatrics is an established
and readily accepted investigation, replacing contrast
radiology in many cases. The range of potential
applications continues to increase. 25 Most
gastrointestinal tract scanning in paediatrics is best
performed with a high-frequency (15–7.5 MHz)
linear or small footprint curvilinear probe.