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Gallstones and Choledocholithiasis


KEY FACTS

Terminology

  • Gallstones: Concretions within biliary system [gallbladder (GB) and biliary ducts]

    • Cholesterol stones (75-80%)

    • Pigment stones (20-25%)

      • –

        "Black" stones in sterile GB; small; common in cirrhosis and hemolytic states

      • –

        "Brown" stones in infected bile (e.g., recurrent pyogenic cholangitis)

  • Sludge: Suspension of particulate material, crystal, and bile within GB

  • Choledocholithiasis: Presence of stones in common bile duct (CBD); usually originate in GB

Imaging

  • Plain films : Detect only 10-20% of cholesterol stones but most pigment stones

  • US detects ~ all GB stones; often misses CBD stones

    • Gallstone: Mobile mass with reflective echo and acoustic shadow within dependent GB

    • Sludge: Mobile, low-level echoes that layer in dependent portion of GB with no acoustic shadow

  • CT detects ~ 80% of gallstones in GB, fewer in CBD

    • Density varies

      • –

        Gas density within central fissures of large cholesterol stones (Mercedes Benz sign)

      • –

        Cholesterol stones are isodense to bile (not detected without rim or nidus of calcification)

      • –

        Higher density in pigment (calcium bilirubinate) stones

    • Sludge: Nonenhancing layered material with attenuation ≥ bile

      • –

        Often not evident on CT (US is more sensitive)

  • MR detects ~ all stones in GB and CBD

    • Usually as signal void; may have bright T2WI signal if stone contains bile

    • MRCP is best for diagnosis of CBD calculi

Top Differential Diagnoses

  • Gallbladder polyp

  • Gallbladder adenomyomatosis

  • Gallbladder carcinoma

  • Gallbladder metastases

Clinical Issues

  • Treatment: Medical or surgical treatment for symptomatic cases

  • Most patients with gallstones or sludge remain asymptomatic

Coronal illustration shows cholelithiasis
and choledocholithiasis
. While most gallstones are asymptomatic, migration of stones to the cystic duct and common duct may cause numerous complications, including biliary colic, cholecystitis, biliary obstruction, and pancreatitis.

Gross photograph shows a gallbladder filled with numerous smooth, yellow cholesterol stones. The gallbladder wall is mildly thickened and hyperemic. (Courtesy G.F. Gray, MD.)

Ultrasound shows multiple asymptomatic gallstones
with posterior acoustic shadowing
. The gallbladder wall is normal
.

Ultrasound of a 66-year-old woman receiving total parenteral nutrition (TPN) shows nonshadowing sludge
and tiny echogenic crystals
within a distended gallbladder. Decreased gallbladder motility associated with TPN results in supersaturation of bile, mucus, and crystals.

TERMINOLOGY

Synonyms

  • Gallstones: Biliary stone, cholelithiasis, choledocholithiasis

  • Sludge: Biliary sludge, microlithiasis, biliary sand, pseudolithiasis, microcrystalline disease

Definitions

  • Gallstones: Concretions within biliary system [gallbladder (GB) and biliary ducts]

    • Cholesterol stone (75-80%): Cholesterol is main constituent

    • Pigment stone (20-25%): Calcium-bilirubinate is main constituent

      • –

        "Black" stone

        • □

          Usually pigment stone in sterile GB; small and tar-like stones frequently associated with cirrhosis and hemolytic states

      • –

        "Brown" stone

        • □

          Usually pigment stone in infected bile duct, associated with cholestasis and biliary infections (e.g., recurrent pyogenic cholangitis)

  • Choledocholithiasis: Presence of stones in common bile duct (CBD)

  • Sludge: Suspension of particulate material and bile in GB

IMAGING

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