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ABDOMINAL ULTRASOUND
disease. The latter usually occurs with polycystic
kidneys, a common autosomal dominant condition
readily recognizable on ultrasound (see Chapter 7),
but may rarely affect the liver alone (Fig. 4.5).
The appearances are of multiple, often septated
cysts, of varying sizes throughout the liver. The
cumulative enhancement behind the numerous
cysts imparts a highly irregular echogenicity to the
liver texture and may make it extremely difficult to
pick up other focal lesions which may be present.
The polycystic liver is usually asymptomatic, but
easily palpable, and if the kidneys are also affected
the abdomen can look very distended. As with
cysts in the kidneys, haemorrhage or infection in a
cyst can cause localized pain. Treatment of the
cysts by drainage is not successful and in rare cases
hepatic transplant offers the only viable option in
patients with intractable symptoms.
Hydatid (echinococcal) cyst
Hydatid disease comes from a parasite, Echinococcus
granulosus, which is endemic in the Middle East but
rare in the UK. The worm lives in the alimentary
tract of infected dogs, which excrete the eggs. These
may then be ingested by cattle or sheep and subsequently
complete their life cycle in a human.
The parasite spreads via the bloodstream to the
liver, where it lodges, causing an inflammatory
reaction. The resulting cyst can be slow-growing
and asymptomatic and may be single or multiple,
depending on the degree of infestation.
Although the appearances are often similar to
those of a simple cyst, the diagnosis can be made by
looking carefully at the wall and contents; the
hydatid cyst has two layers to its capsule, which may
appear thickened, separated or detached on ultrasound.
Daughter cysts may arise from the inner capsule—the
honeycomb or cartwheel appearance (Fig.
4.6). Thirdly, a calcified rind around a cyst is usually
associated with an old, inactive hydatid lesion.
The diagnosis of hydatid, as opposed to a simple
cyst, is an important one as any attempted aspiration
may spread the parasite further by seeding
along the needle track if the operator is unaware of
the diagnosis.
Management of hepatic hydatid cysts has traditionally
been surgical resection. However, considerable
success has now been achieved using
percutaneous ultrasound-guided aspiration with
sclerotherapy. 3
Abscesses
Clinical features of an abscess
Patients present with fever, often accompanied by
right upper quadrant (RUQ) pain and vomiting.
Abnormal liver function tests (LFTs) and anaemia
Figure 4.5 Multiple cysts in the liver. In this case the
kidneys are normal. Polycystic liver is more usually
associated with polycystic kidney disease.
Figure 4.6 Hydatid cyst demonstrating surrounding
daughter cysts.