Diagnostic Approach to Isolated Cholestasis

Initial Diagnostic Approach

The American College of Radiology recommends abdominal ultrasound as the first-line imaging test to evaluate dilation of intra- and extra-hepatic bile ducts, search for bile duct stones, and identify mechanical obstruction in patients with isolated cholestase 1, 2, 3
Ultrasound can quickly distinguish between extra-hepatic cholestasis (dilation of bile ducts) and intra-hepatic cholestasis (non-dilated bile ducts) 1, 2, 3
The absence of extra-hepatic bile duct dilation suggests intra-hepatic cholestasis 3

The European Association for the Study of the Liver recommends systematic measurement of anti-mitochondrial antibodies (AMA) in all adults with chronic intra-hepatic cholestasis to screen for primary biliary cirrhosis 1, 2
AMA are positive in more than 90% of patients with primary biliary cirrhosis, with a specificity of more than 95% 1
A titre of AMA ≥1/40 associated with elevated alkaline phosphatase for at least 6 months allows for a confident diagnosis of primary biliary cirrhosis 1
Measurement of total and conjugated bilirubin, albumin, and prothrombin time is also recommended to evaluate liver function 1, 4

If ultrasound is normal but cholestasis persists, magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) should be performed as a second-line test 1, 2, 3, 4
MRCP is superior to ultrasound for detecting choledocholithiasis (sensitivity 95-96%), bile duct stenosis, and intra-hepatic bile duct anomalies 3, 4, 5
MRCP allows for non-invasive evaluation of intra- and extra-hepatic bile ducts and liver parenchyma 3

Endoscopic ultrasonography (EUS) is an alternative to MRCP for evaluating distal bile duct obstruction 1, 2
EUS is particularly useful when MRCP is not available or contraindicated 1

If AMA are negative, a liver biopsy should be considered in patients with unexplained intra-hepatic cholestasis 1, 2
The biopsy should contain at least 10 portal spaces due to the high variability of sampling in small bile duct diseases 2
The biopsy allows for classification of lesions into three categories: bile duct involvement, non-bile duct involvement, and hepatocellular cholestasis with minimal histological abnormalities 1, 2

Genetic testing for ABCB4 (encoding the phospholipid export pump) should be considered in patients with negative AMA and histological lesions compatible with primary biliary cirrhosis or primary sclerosing cholangitis 1

Diagnostic endoscopic retrograde cholangiopancreatography (ERCP) should be reserved for highly selected cases 1, 2, 5
ERCP carries significant morbidity: pancreatitis 3-5%, bleeding 2%, cholangitis 1%, mortality 0.4% 2, 5
If no therapeutic intervention is anticipated, MRCP or EUS should be preferred 1, 2
ERCP should be reserved for situations where therapeutic intervention is necessary (e.g., stone extraction, stent placement) 1, 5