HEPATOBILIARY ULTRASOUND REFERRAL PATTERNS
Category: Diagnostic Radiology
Abstract : REFERRAL PATTERNS FOR HEPATOBILIARY ULTRASOUND There is an almost infinite
number of reasons for performing abdominal ultrasound. Some of the more common
referrals are discussed below. Jaundice This symptom is a frequent
cause of referral for abdominal ultrasound. It is therefore essential for the
sonographer to have a basic understanding of the various mechanisms in order to
REFERRAL PATTERNS FOR HEPATOBILIARY ULTRASOUND
There is an almost infinite
number of reasons for performing abdominal ultrasound. Some of the more common
referrals are discussed below.
Jaundice
This symptom is a frequent
cause of referral for abdominal ultrasound.
It is therefore essential for the
sonographer to have a basic understanding of the various mechanisms in order to
maximize the diagnostic information from the ultrasound scan. Jaundice, or
hyperbilirubinaemia, is an elevated level of bilirubin in the blood. It is
recognized by a characteristic yellow coloration of the skin and sclera of the
eye, often accompanied by itching if prolonged. Bilirubin is derived from the
haem portion of haemoglobin. Red blood cells are broken down in the liver into
haem and globin, releasing their bilirubin, which is non-soluble. This is termed
unconjugated bilirubin. This is then taken up by the liver cells and converted
to a water-soluble form, conjugated bilirubin, which is excreted via the biliary
ducts into the duodenum to aid fat digestion. By knowing which of these two
types of bilirubin is present in the jaundiced patient, the clinician can narrow
down the diagnostic possibilities. Ultrasound then further refines the
diagnosis.
Jaundice can fall into one of two categories:
● obstructive
(sometimes called posthepatic) in which the bile is prevented from draining out
of the liver because of obstruction to the biliary duct(s)
● non-obstructive
(prehepatic or hepatic) in which the elevated bilirubin level is due to
haemolysis (the breakdown of the red blood cells) or a disturbance in the
mechanism of the liver for uptake and storage of bilirubin, such as in
inflammatory or metabolic liver diseases. Naturally, the treatment of jaundice
depends on its cause. Ultrasound readily distinguishes obstructive jaundice,
which demonstrates some degree of biliary duct dilatation, from nonobstructive,
which does not.
Abnormal liver function tests
Altered or deranged
liver function tests (LFTs) are another frequent cause of referral for abdominal
ultrasound. Biochemistry from a simple blood test is often a primary pointer to
pathology and is invariably one of the first tests performed as it is quick and
easily accessible. Most of these markers are highly unspecific, being associated
with many types of diffuse and focal liver pathology.
Other common
reasons for referral
In some cases, the presenting symptoms may be
organ-specific or even pathognomonic, simplifying the task of ultrasound
diagnosis. Often, however,the symptoms are vague and non-specific, requiring the
sonographer to perform a comprehensive and knowledgeable search. The
non-invasive nature of ultrasound makes it ideal for the first-line
investigation.
Upper abdominal pain
● Upper abdominal pain, the origin
of which could be linked to any of the organs, is one of the most frequent
causes of referral. The sonographer can narrow the possibilities down by taking
a careful history.
● Is the pain focal? This may direct the sonographer to
the relevant organ, for example a thick-walled gallbladder full of stones may be
tender on gentle transducer pressure, pointing to acute or chronic
cholecystitis, depending on the severity of the pain.
● Bear in mind that
gallstones are a common incidental finding which may be a red herring. Always
consider multiple pathologies.
● Is the pain related to any event which may
give a clue? Fat intolerance might suggest a biliary cause, pain on micturition
a urinary tract cause, for example.
● Is it accompanied by other symptoms
such as a high temperature? This may be associated with an infective process
such as an abscess.
● Could it be bowel-related? Generalized abdominal pain
could be due to inflammatory or obstructive bowel conditions and knowledge of
the patient’s bowel habits is helpful.
● Has the patient had any previous
surgery which could be significant?
Palpable right upper quadrant
mass
A palpable right upper quadrant mass could be due to a renal,
hepatobiliary, bowel-related or other cause. The sonographer should gently
palpate to get an idea of the size and position of the mass and whether or not
it is tender. Specifically targeting the relevant area may yield useful and
unexpected results, for example a Reidel’s lobe, colonic carcinoma or impacted
faeces, which will help to guide the nature of further investigations.
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