9%20ECOGRAFIA%20ABDOMINAL%20COMO%20CUANDO%20DONDE

THE RETROPERITONEUM AND GASTROINTESTINAL TRACT 201
F
G
Figure 8.4 cont’d (F) Normal, pulsatile spectrum from the proximal IVC is influenced by the proximity of the right
atrium. (G) The waveform from the distal IVC is lower in velocity, less pulsatile and displays more variance.
enters the IVC in around 10% of renal carcinoma
cases. Tumour thrombus from hepatic or adrenal
masses can also invade the IVC.
Coagulation disorders, which cause Budd–
Chiari syndrome (see Chapter 4) predominantly
affect the hepatic veins, but may also involve the
IVC (Fig. 8.5).
Patients may require the insertion of a caval filter,
which is performed under X-ray guidance, but
may be monitored for patency using ultrasound
with Doppler.
Dilatation of the IVC is a finding commonly
associated with congestive heart failure, and is frequently
accompanied by hepatic vein dilatation.
Compression of the IVC by large masses is not
uncommon. This may be due to retroperitoneal
masses, such as a large lymph node, or liver masses
such as tumour or caudate lobe hypertrophy.
Colour or power Doppler is particularly useful in
confirming patency of the vessel and differentiating
extrinsic compression from invasion. Insertion of
metallic stents may be performed under angiographic
control to maintain the vessel patency, particularly
if the compression is due to inoperable
hepatic metastasis (Fig. 8.6).
Tumours of the IVC are rare. Leiomyosarcoma
is a primary IVC tumour, appearing as a hyperechoic
mass in the lumen of the vein. 4,5 This causes
partial or complete obstruction of the IVC, resulting
in Budd–Chiari syndrome. In partial occlusion,
the hepatic veins and proximal IVC may be considerably
dilated. Resection of the tumour, with
repair of the IVC, is possible provided the adjacent
liver is not invaded. 4
THE ADRENAL GLANDS
Normal appearances
The normal adrenal glands can be seen on ultrasound
in the vast majority of patients, 6,7 if you know
where and how to look. Each adrenal gland is constructed
with a central fold or ridge, which points
anteromedially, from which extend two thin ‘wings’
of tissue—a medial and a lateral wing (Fig. 8.7).
The ultrasound appearances are therefore of a
< shape in LS, or a thin, linear structure as the
transducer is moved medially towards the central
ridge.
The wings of the gland appear hypoechoic and
are no more than 2 mm in thickness.
Ultrasound technique
For the right adrenal, use the liver as an acoustic
window. Scan the upper pole of the kidney intercostally
through the liver, and angle slightly medially
to the kidney, where the gland can be located
between the liver and the diaphragmatic crus (Fig.
8.7A). Continue angling slightly medially towards
the IVC and the central ridge of the gland is seen
behind the IVC (Fig. 8.7B).
For the left gland the spleen must be used as a
window. To avoid overlying bowel this is best
achieved with the patient supine, using a coronal
section. When the upper pole of the left kidney is
located through the spleen, the left adrenal can be
seen in the small triangular area between the
spleen, kidney and diaphragmatic crus (Fig.
8.7D). 6,7