Imaging Methods
The methods used in evaluating the jaundiced patient currently include ultrasound (US),
computed tomography (CT),
magnetic resonance cholangiopancreatography (MRCP),
endoscopic retrograde cholangiopancreatography (ERCP),
and endoscopic US (EUS).
Ultrasound
US is the initial imaging test of choice in jaundiced patients because it is non-invasive,
inexpensive and readily available.
US is used to determine the presence of obstructive jaundice by depicting dilated bile ducts,
with sensitivity of 55% to 95% and specificity of 71% to 96%.
False-negative studies are due to 2 factors: inability to visualize the extrahepatic biliary tree (often because of interposed bowel gas) and the absence of biliary dilation in the presence of obstruction.
US is less effective than CT or MRCP for determining the site and the cause of obstruction.
Computed Tomography
CT is slightly more sensitive (74% to 96%) and specific (90% to 94%) than US for detecting biliary obstruction,
especially given the advent of multidetector CT and image reformations[1,2,3,5]; in addition,
the ability to determine the site and the cause of obstruction is greater with CT than with US.
It also allows better evaluation of the portal and retroperitoneal lymph nodes and vascular structures[2].
CT is strongly recommended as the primary modality for evaluating patients with suspected malignant biliary obstruction,
both for diagnosis,
staging and predicting tumor extension and potential resectability.
CT cholangiopancreatography generated by slab volume imaging with minimum-intensity projections and curved planar reformations may be useful for pre-intervention planning.
The major advantages of spiral CT over ERCP or EUS include its low level of invasiveness,
minimal operator dependence,
low technical failure rate and,
in contrast to ERCP,
ability to produce a three-dimensional image of the biliary tree.
The major limitations of CT are the inability to detect small peritoneal implants,
small hepatic metastases,
lymph node metastasis in normal-sized nodes,
and intraductal tumour extent.
Spiral CT gives a relatively high dose of radiation topatients and a further drawback is a small risk of adverse reaction to the iodinated contrast agents.
Its main limitation is in patients with impaired renal function with high serum creatinine levels,
as contrast may be nephrotoxic.
Artefacts produced by patient movement,
respiration and support devices also limit diagnostic value.
Magnetic resonance imaging
Magnetic resonance imaging (MRI)can demonstrate both the site and cause of biliary obstruction.
MR cholangiography has been shown to be useful in depicting the 3-dimensional anatomy of the biliary and pancreatic ducts.
For detection of ductal calculi,
MRCP is the most sensitive of the non-invasive techniques.
MRCP constitutes a non-invasive alternative if ERCP is unsuccessful or cannot be performed.
It has a high diagnostic precision (>94%) for the diagnosis of bile duct obstruction,
choledocholithiasis,
and malignant bile duct obstruction.
The major advantages of MRCP are that it is non-invasive,has no ionising radiation or contrast material,
and allows diagnosis and treatment planning in many patients without invasive cholangiography.
The major limitations of MRCP are its inability to offer therapeutic opportunity,
its low spatial resolution and its availability and cost .
Endoscopic retrograde cholangiopancreatography
ERCP is the most common invasive diagnosticbiliary procedure and has evolved gradually from its initial role as a diagnostic tool.
ERCP is generally reserved for therapeutic interventions,
such as the removal of stones or dilatation of strictures.
ERCP can also be used to obtain tissue from biliary strictures (via brushings) to identify malignancy.
Therapeutic procedures via ERCP are successful at about 90% of the cases.
The most common complications after ERCP are acute pancreatitis and cholangitis,
which are severe in 1% of patients.
Because of its inherent risks,
costs,
and invasive nature,
and due to significant advances in cross-sectional imaging,
in particular the advent of MRCP,
ERCP should be indicated only for therapeutic reasons or when it can alter patient management.
Endoscopic ultrasonography
EUS can be used as an adjunct examination to ERCP in cases of common bile duct obstruction and can be used to determine whether the obstruction is from mass or stone with high sensibility and specificity.
Causes of jaundice in adults
According to the clinic and the seat of the obstruction on the biliary tract,
the main causes of jaundice in adults are listed in figure1 and table1 (Tab.1)
Tab.1:
Extrahepatic causes of cholestatic jaundice
|
Benign pathologies
|
Malignant pathologies
|
- Stones of the bile ducts and choledocholithiasis
- Complicated hydatid cyst
- Benign bile duct strictures
- Sclerosing cholangitis
- Pancreatic pseudo-cysts
- Chronic pancreatitis
- Choledochal cyst
|
- Pancreatic carcinoma
- Cholangiocarcinoma of either the proximal or distal duct
- Ampullary tumors
- Biliary compression by lymph nodes
- Carcinoma of gallbladder
- Metastatic cancer
- Tumor infiltration
|
Intrahepatic causes of cholestatic jaundice
|
- Hepatitis (alcoholic,
non-alcoholic and autoimmune hepatitis)
- Cirrhosis
- Drug-induced jaundice
- Primary sclerosing cholangitis
- Infiltrative and granulomatous diseases
|