This 84 year-old man presented with jaundice and epigastric pain. Several biliary calculi are shown within the dilated distal common bile duct on this abdominal ultrasound.

While common bile duct calculi can be diagnosed with ultrasound, the sensitivity is low (50-60%). Failure to detect calculi may be due to a non-distended duct or to overlying bowel gas. The gold standard for detection of common bile duct calculi is endoscopic retrograde cholangiopancreatogram (ERCP). ERCP is invasive and carries a risk of complications. The most sensitive non-invasive test is magnetic resonance cholangiopancreatogram (MRCP), with reported sensitivity of 81-100% and specificity of 85-100%. The typical finding on MRCP is dark filling defects within the duct. MRCP also may be combined with abdominal MRI to provide information about surrounding soft tissue structures. Non-enhanced helical CT has an intermediate sensitivity of 75-85%.

Bile duct calculi may be classified as primary (forming within the ducts) or secondary (forming within the gallbladder, and passing into the ducts).

Primary bile duct calculi are uncommon in Western countries (5%). They are predominantly pigment stones, and causes include: chronic haemolysis; recurrent cholangitis; congenital anomalies such as Caroli’s disease; sphincter of Oddi dysfunction; and Clonorchis sinensis or Ascaris infection.

Secondary bile duct calculi are more common (95%). Causes include: obesity; Crohn’s disease; ileal resection; haemolytic anaemia; and hypertriglyceridaemia. Most are idiopathic. They are commonly associated with gallbladder calculi.

Calculi <3mm usually pass spontaneously. Calculi 3-10mm are often treated with endoscopic sphincterotomy and balloon or basket retrieval. Calculi >10mm may require mechanical lithotripsy.

Reference: Federle, M P, et al. Diagnostic Imaging. Abdomen. 1st edition, Amirsys, 2004.

Credit: Dr Laughlin Dawes