Page 194 - Medicine and Surgery

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190 Chapter 5: Hepatic, biliary and pancreatic systems

Vitamin K deficiency including that caused by obstruc- the biliary tree suggests infection with gas-producing
tive jaundice (due to reduced absorption from the intes- organisms, trauma, a fistula between the intestine and
tine) causes a prolonged PT (see page 465). Parenteral gallbladder, or may be seen after endoscopic or surgical
replacementofvitaminKshouldleadtoimprovementof instrumentation.
the prolonged PT within a few days if hepatic synthetic
Abdominal ultrasound scan (USS)
function is intact.
This is a safe, non-invasive test, which can be used to
visualise the liver, biliary tree and pancreas. It is partic-
Pancreatic function tests ularly useful in patients who have
jaundice or abnormal liver function tests where it is
Exocrine function
useful to look for gallstones, dilated intra- or extra-
Serum amylase is a marker for pancreatic damage.

hepatic bile ducts, and to assess the size and appear-
Arise of more than 4 times normal with suggestive
ance of the liver.
clinical features is diagnostic of acute pancreatitis, al-
signs of chronic liver disease.
though lesser rises may occur due to other causes, e.g.
mesenteric infarction and acute cholecystitis. A nor- hepatomegaly or splenomegaly.
mal amylase level does not exclude acute pancreatitis. suspected gallstone disease, including cholecystitis.
Serum lipase is also a marker for pancreatic damage. acute pancreatitis, particularly to look for gallstones,
Steatorrhea which is thought to be caused by chronic
pseudocysts and abscesses.
pancreatitis may be investigated using faecal fat esti- suspected intra-abdominal abscess, e.g. liver abscess
mation and/or a breath test to compare the absorp- including amoebic abscess.
tion of a radiolabelled fatty acid versus a radiolabelled Other abnormal findings include ascites, abdominal
triglyceride. If the fatty acid is absorbed normally but masses and lymphadenopathy. Ultrasound may also be
the more complex triglyceride is not, then the steator- used for liver biopsy, and doppler ultrasound is used to
rhea is caused by pancreatic disease. look for hepatic blood flow, particularly portal vein flow
Other tests to assess the exocrine function, such as
direction and venous patency.
measuring the levels of enzymes in the duodenum
Computed tomography (CT)
after a food challenge, are available but not commonly
This can visualise the liver, biliary tree, lymph nodes and
performed.
the pancreas in more detail. Preferably a spiral CT is per-
formed after intravenous contrast, as this allows imaging
Endocrine function
in the arterial and portal venous phases, which charac-
Chronic pancreatitis may lead to secondary diabetes

terises liver lesions more precisely. Precautions should be
mellitus. Tests for endocrine function in this context
taken in case of allergy or risk of contrast nephrotoxicity.
are not required.
This includes stopping metformin and ensuring patients
Endocrine tests may be needed in the diagnosis of islet

are well-hydrated prior to the tests. CT is particularly
cell tumours. Pancreatic polypeptide is raised in all of
useful for assessing focal lesions of the liver, staging of
these types of tumour and see page 222 for specific
malignancy, and it is more sensitive for pancreatic le-
tests.
sions, such as assessing the severity of acute pancreatitis
and to look for complications such as pseudocysts.
Imaging of the liver, biliary system
and pancreas Magnetic resonance imaging (MRI) and
magnetic resonance
Plain abdominal X-ray cholangiopancreatography (MRCP)
This is usually unhelpful, but occasionally abnormali- This is sometimes used for more sensitive imaging of
ties may be detected. Up to 10% of gallstones are radio- the liver, particularly for focal lesions. MRCP is some-
opaqueandvisibleonX-ray.Pancreaticcalcificationmay times used as a non-invasive alternative to endoscopic
be seen in chronic pancreatitis. The finding of air in retrograde cholangiopancreatography (ERCP) to