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ABDOMINAL ULTRASOUND
areas of necrosis within them. Most are benign, but
5–10% are malignant. It presents on a background
of episodic, severe hypertension and the urine contains
catecholamines. (Although this is also a feature
of adrenal neuroblastoma, the latter is
predominantly a childhood tumour.) These lesions
should be treated with great care—vigorous palpation
may precipitate a severe hypertensive episode
and biopsy should therefore be avoided.
Although most phaeochromocytomas arise in the
adrenal glands, and are therefore demonstrable on
ultrasound, those arising in the sympathetic chain
may be obscured by bowel gas and are not possible
to exclude on ultrasound (Fig. 8.8D, E). If there
remains biochemical evidence of phaeochromocytoma
in the presence of normal adrenal glands,
a Meta-Iodobenzylguanidine isotope scan will
demonstrate increased activity in a phaeochromocytoma
and CT scan can then be targeted to the
appropriate area.
Phaeochromocytomas are also associated with
von Hippel–Lindau syndrome.
Adrenal carcinoma
Primary adrenal carcinomas are rare in the adult.
They are commonly endocrinologically inactive in
adults, and therefore tend to present late when
they are quite large. They may invade the IVC and
metastasize to the liver. Surgical removal of
tumours in the absence of liver metastases has a
good prognosis 9 and, in patients with metastases,
radiofrequency ablation of the adrenal mass may
have some benefit in prolonging survival. 10
GASTROINTESTINAL (GI) TRACT
Contrast radiographic investigations, including CT,
are generally accepted as the methods of choice for
investigating diseases of the GI tract. Although ultrasound
is not considered a primary tool in the investigation
of bowel lesions, as the gas-filled lumen
makes visualization difficult in many cases, ultrasound
is remarkably successful in diagnosing GI
tract pathology in the hands of an experienced operator.
GI tract ultrasound can be time-consuming,
but a wealth of information can be obtained with a
high-frequency linear probe in a symptomatic
patient. Considerable diagnostic benefit has been
shown for careful, targeted, percutaneous ultrasound
of the large and small GI tract using high-frequency
transducers. 11
It is important to be aware of the variable ultrasound
appearances of normal bowel, as it may be
responsible for mimicking other pathology.
Normal bowel is frequently difficult to examine on
ultrasound as the gas-filled lumen reflects the
sound, requiring careful compression techniques.
Abnormal bowel is particularly accessible to ultrasound,
however. A fluid-filled lumen also make
easy the demonstration of valvulae conniventes of
the small bowel and haustra of the large colon.
Oesophagus and stomach
The oesophagus is not usually accessible to percutaneous
ultrasound; however, the lower end can be
demonstrated as it passes through the diaphragm in
the midline, just anterior to the aorta (Fig. 8.9A).
Its normal appearances should not be confused with
a mass. Occasionally, ultrasound demonstrates the
thickened wall associated with an oesophageal carcinoma
involving the lower oesophagus (Fig. 8.9B).
Endoscopic ultrasound (EUS), with its high frequency
and proximity to the relevant structures, is
able to demonstrate the layers of the gut wall, and
to demonstrate pathology and accurately stage
malignant disease in both the oesophagus and
stomach, and also to guide invasive procedures. 12,13
Barium X-ray studies are still the first-line investigation
of choice for many potential GI tract conditions;
however, endoscopy is regarded as the
gold standard for investigating the lining of the
stomach and duodenum and can be combined
with biopsy when necessary. Although percutaneous
ultrasound has had modest success in revealing
stomach masses if the stomach is filled with
water, 14 it can never replace endoscopy. However,
if such lesions are discovered, this helps to direct
subsequent radiological management (Fig. 8.10).
Appendix
Acute appendicitis is a common diagnosis on
admission to the casualty department with right
lower abdominal pain. However around 15–25% of