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42
ABDOMINAL ULTRASOUND
Table 3.1
Gallstones—clinical features
Often asymptomatic
Biliary colic—RUQ pain, fatty intolerance
+ve ultrasound Murphy’s sign (if inflammation is present)
Recurring (RUQ) pain in chronic cholecystitis
Jaundice (depending on degree of obstruction)
Fluctuating fever (if infection is present)
RUQ=right upper quadrant.
scanning a patient with abdominal pain it should
not automatically be assumed that, when gallstones
are present, they are responsible for the pain. It is
not uncommon to find further pathology in the
presence of gallstones and a comprehensive upperabdominal
survey should always be carried out.
Gallstones are associated with a number of conditions.
They occur when the normal ratio of
components making up the bile is altered, most
commonly when there is increased secretion of cholesterol
in the bile. Conditions which are associated
with increased cholesterol secretion, and therefore
the formation of cholesterol stones, include obesity,
diabetes, pregnancy and oestrogen therapy. The
incidence of stones also rises with age, probably
because the bile flow slows down.
An increased secretion of bilirubin in the bile, as
in patients with cirrhosis for example, is associated
with pigment (black or brown) stones.
Ultrasound appearances
There are three classic acoustic properties associated
with stones in the gallbladder; they are highly
reflective, mobile and cast a distal acoustic shadow.
In the majority of cases, all these properties are
demonstrated (Figs 3.1–3.3).
Shadowing
The ability to display a shadow posterior to a stone
depends upon several factors:
●
●
The reflection and absorption of sound by the
stone. This is fairly consistent, regardless of the
composition of the stone.
The size of the stone in relation to the beam
width. A shadow will occur when the stone
A
B
Figure 3.1 (A) Longitudinal section and (B) transverse
section images of the gallbladder containing stones with
strong distal acoustic shadowing. Note the thickened
gallbladder wall.
Figure 3.2 Multiple tiny stones combining to form a
posterior band of shadow.