Malignant biliary tract obstruction (summary)

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This is a basic article for medical students and other non-radiologists

Malignant biliary tract obstruction (MBTO) represents a group of conditions that cause obstructive jaundice. While most examples are the result of pancreatic head cancers, other malignancies may be causative.

Reference article

This is a summary article; we do not have a more in-depth reference article for this topic, but you can read more about pancreatic cancer and cholangiocarcinoma.

Summary

  • epidemiology
    • reflects the common causes, e.g. head of pancreas cancer
      • predominantly a condition of the elderly
      • 80% over the age of 60
  • presentation
    • jaundice (90%) in the context of weight loss
    • may be associated central abdominal pain
    • presentation is relatively late
    • a palpable mass may be evident on examination
  • pathophysiology
    • obstruction of the biliary tree occurs along the CBD
      • head of pancreas tumors (commonest)
      • cholangiocarcinoma
      • other tumors: gallbladder, duodenal, ampullary cancers
      • metastatic disease
  • investigation
    • ultrasound is the first-line test in jaundice
    • CT/MR to further assess the obstructing mass lesion
    • intervention to help decompress the system if needed
  • treatment
    • despite improvement in treatments prognosis remains dismal
      • 5-year survival of pancreatic cancer is less than 5%

Role of imaging

  • determine if there is biliary dilatation
  • assess the level of obstruction
  • characterize the mass
  • look for distant spread
  • aid in decompression of the obstructed system

Radiographic features

Ultrasound

Ultrasound is the best first test since it is cheap, easily accessible and quick. It will identify biliary duct dilatation and be able to assess the level of obstruction.

In many cases, it will be able to identify the obstructing lesion as a mass rather than a gallstone.

CT

CT with contrast will give more anatomic information than the ultrasound. It will help confirm the location of the mass lesion and identifying where the lesion has arisen. CT is very useful for mapping the vascular supply around tumors which is invaluable when planning surgical options. It may also be useful for local staging and potentially for identifying any metastatic disease.

MRI

MRI may be used to assess the level of obstruction (MRCP) and can be used to characterize liver lesions.

PTC and drainage

A percutaneous transhepatic cholangiogram allows a radiologist to access the dilated biliary tree from above the level of obstruction and decompress the system. Depending on the cause and completeness of obstruction, this may be considered as a temporising measure while the treatment plan is determined.

Medical student radiology curriculum