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

62
ABDOMINAL ULTRASOUND
Table 3.4
Causes of biliary duct dilatation
Intrinsic
—Stones
—Carcinoma of the ampulla of Vater
—Cholangiocarcinoma
—Stricture (associated with chronic pancreatitis)
—Biliary atresia/choledochal cyst
—Post-liver-transplantation bile duct stenosis (usually
anastomotic)
—Parasites
—Age-related or post-surgical mild CBD dilatation
Extrinsic
—Carcinoma of the head of pancreas
—Acute pancreatitis
—Lymphadenopathy at the porta hepatis
—Other masses at the porta, e.g. hepatic artery
aneurysm, gastrointestinal tract mass
—Intra-hepatic tumours (obstruct distal segments)
Diffuse hepatic conditions
—Sclerosing cholangitis
—Caroli’s disease
ERCP, although invasive, is a more accurate
method of examining the CBD and will often identify
strictures or small calculi not visible on ultrasound.
It has the advantage of a therapeutic role in
Figure 3.32
Sites of possible gallstone obstruction.
addition to its diagnostic capabilities, by allowing
the extraction of stones at the time of diagnosis. It
is associated with a small risk of complication, however,
and its use is therefore increasingly limited in
favour of the non-invasive magnetic resonance
cholangiopancreatography (MRCP) (Fig. 3.34F).
MRCP has been found to be highly effective in
the diagnosis of CBD stones 24 and can potentially
avoid the use of purely diagnostic ERCP. 25
SAG RT
LOBE
HA
PV
A
B
Figure 3.33 (A) Dilated biliary ducts do not demonstrate flow on colour Doppler, differentiating them from portal
vessels. (B) Originally suspected as a dilated biliary tree, colour Doppler demonstrates that the ‘extra tubes’ are, in fact,
dilated intrahepatic arteries in a patient with end-stage chronic liver disease with reversed portal venous flow.