Choledocholithiasis – Causes, Symptoms, Treatment

Choledocholithiasis is the presence of stones within the common bile duct (CBD). It is estimated that common bile duct stones are present in anywhere from 1-15% of patients with cholelithiasis. The present-day treatment of bile duct stones is endoscopic retrograde cholangiopancreatography (ERCP), or in some cases, laparoscopic cholecystectomy with bile duct exploration. In most US centers, when bile duct stones present, ERCP is usually followed with laparoscopic cholecystectomy.[rx][rx][rx]

Causes of Choledocholithiasis

• Choledocholithiasis occurs as a result of either the formation of stones in the common bile duct or the passage of gallstones that are formed in the gallbladder into the CBD.
• Bile stasis, bactibilia, chemical imbalances, increased bilirubin excretion, pH imbalances, and the formation of sludge are some of the factors which lead to the formation of these stones.
• Less commonly, stones are formed in the intrahepatic biliary tree, termed primary hepatolithiasis, and may lead to choledocholithiasis.
• Stones that are too large to pass through the ampulla of Vater remain in the distal common bile duct, causing obstructive jaundice that may lead to pancreatitis, hepatitis, or cholangitis.
• Gallstones are differentiated by their composition. Cholesterol stones are composed mainly of cholesterol, while black pigment stones are mainly made of pigment, and brown pigment stones are composed of a mix of pigment and bile lipids. Cholesterol stones make up approximately 75% of the secondary common bile duct stones in the United States, while black pigment stones comprise the remainder. Primary common bile duct stones are usually brown pigment stones. Obstruction of the CBD by gallstones leads to symptoms and complications that include pain, jaundice, and sepsis.[rx][rx]

Symptoms Of Choledocholithiasis

Diagnosis of Choledocholithiasis

The provider should order a

• White blood cell count,
• Hemoglobin/hematocrit
• Platelet count,
• Total bilirubin,
• Direct bilirubin,
• Alkaline phosphatase,
• Aspartate aminotransferase,
• Alanine aminotransferase.
• In a patient with cholelithiasis, total bilirubin of greater than 3 mg/dL to 4 mg/dL, is strongly associated with choledocholithiasis.
• Gamma-glutamyl transpeptidase is also elevated.
• Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) concentrations are elevated in biliary obstruction in a cholestatic pattern, with increases in alkaline phosphatase,
• Serum bilirubin and gamma-glutamyl transpeptidase (GGT) exceeding the elevations in serum AST and ALT.

Imaging

• A transabdominal ultrasound –  is the first test that should be ordered for the patient suspected of any biliary disease, including choledocholithiasis. In most cases, an abdominal ultrasound will show a dilated common bile duct (more than 6 mm) and stones within the common bile ducts.
• The detection of CBD stones – is typically impeded by the presence of gas in the duodenum, but ultrasound can identify CBD dilatation accurately with up to 90% accuracy.
• Abdominal ultrasonography – has a sensitivity of 15-40% for detecting CBD stones. If a strong suspicion still exists based on history, physical, and laboratory findings in the face of a negative ultrasound.
• Magnetic resonance cholangiopancreatography (MRCP) – can be ordered. MRCP is also a noninvasive test with 92% sensitivity and a specificity of 100%.
• Endoscopic ultrasound  –  also can be used to identify suspected choledocholithiasis, but it is more invasive than a transabdominal ultrasound or MRCP. This entails the introduction of an ultrasonic probe into the duodenum under endoscopic guidance.

Ultrasound

• Although ultrasound is usually the first investigation for biliary disease, it has average sensitivity for the detection of biliary stones within the bile duct. Sensitivity has been variably reported between 13-55% , with newer studies having higher values due to improved equipment.
• Ultrasound should be performed both longitudinally and transversely through the duct with particular attention paid to the very distal portion of the common bile duct as it passes through the pancreatic head (best assessed transversely).

Findings include

Visualization of stone(s)

• echogenic rounded focus
• size ranges between 2 to >20 mm
• shadowing may be more difficult to elicit than with gallstones within the gallbladder
• ~20% of common bile duct stones will not shadow
• twinkling artefact may be useful to detect occult stones.

Dilated bile duct

• >6 mm + 1 mm per decade above 60 years of age
• >10 mm post-cholecystectomy
• dilated intrahepatic biliary tree
• gallstones should increase suspicion, especially if multiple and small

Recently endoscopic ultrasonography (EUS) has also been used with very high sensitivity and specificity.

CT

Routine contrast-enhanced CT is moderately sensitive to choledocholithiasis with a sensitivity of 65-88% but it requires attention to a number of potentially subtle findings. These include:

• Target sign
  • central rounded density: stone
  • surrounding lower attenuating bile or mucosa
• Rim sign – stone is outlined by thin shell of density
• Crescent sign – bile eccentrically outlines luminal stone, creating a low attenuation crescent
• Calcification of the stone – unfortunately only 20% of stones are of high density

Setting window level to the mean of the bile duct and setting the window width to 150 HU has been reported to improve sensitivity. Biliary dilatation should also be visible.

CT cholangiography

CT with prior administration of biliary excreted contrast agents is highly sensitive (88-96%) and specific (88-98%) ⁸ for choledocholithiasis. The difficulty is, however, two-fold:

• contrast agents have relatively high complication rates
• obstructive cholestasis diminishes excretion, and thus is only viable in patients with largely normal liver function tests

MRCP

• Magnetic resonance cholangiopancreatography (MRCP) has largely replaced ERCP as the gold standard for diagnosis of choledocholithiasis, able to achieve similar sensitivity (90-94%) and specificity (95-99%) without ionizing radiation, intravenous contrast, or the complication rate inherent in ERCP.
• Filling defects are seen within the biliary tree on thin cross-sectional T2 weighted imaging. Care should be taken not to use thick slabs for the diagnosis as volume averaging may obscure smaller stones.
• However, if the diagnosis has already been secured by ultrasound or CT, there is no additional value of MRCP, and the next step is therapeutic ERCP (see below).

Percutaneous or oral cholangiography

• Both investigations are no longer used for routine diagnosis having been replaced by ultrasound, CT and MRCP.

Treatment of Choledocholithiasis

The treatment for choledocholithiasis is the removal of the obstructing stones via endoscopic means. An ERCP can be performed under general anesthesia, with the patient in either prone, left lateral, or supine position, though prone is the most common position used.

• Indomethacin – However, a one-time dose of 50 mg to 100 mg rectal indomethacin can be used, prevent post-procedure pancreatitis if the pancreatic duct was manipulated during an ERCP.
• Antibiotics  – are typically not needed for choledocholithiasis unless the patient also has associated cholecystitis or cholangitis.
• The endoscopist – will then place a duodenoscope into the second portion of the duodenum and advance a catheter and guidewire into the common bile duct. A sphincterotome then is used to cut the papilla, using cautery, and enlarge the ampulla of Vater.
• Often the stones – will be released with this maneuver. A variety of snares and baskets can be used to grasp the stones and remove them if needed.
• A balloon catheter – also can be used to sweep the common bile duct to remove any stones. The endoscopist also can place a stent in the common bile duct, which will serve two purposes. First, any remaining stones will be softened, and potentially easier to remove with a second ERCP.
• Second, the stent will allow bile drainage – to occur, preventing obstructive jaundice. If the stones are large, stuck, or there are many stones within the biliary tree, surgical removal is indicated.

Surgery

• A laparoscopic – or open common bile duct exploration is needed to remove any stones that can not be removed via endoscopic methods. An elective cholecystectomy is also recommended, during the same hospital admission, to prevent future episodes of choledocholithiasis.[rx][rx][rx]
• Cholecystectomy – in patients with choledocholithiasis remains controversial, but most experts recommend it. Arguments can be made against cholecystectomy in patients who cannot tolerate surgery well (eg, due to age, medical problems), as long as the organ is asymptomatic.
• Cholecystectomy – is not indicated for primary CBD stones. Other surgical options include open choldochotomy, transcystic exploration (a technique to clear the CBD of stones during laparoscopic cholecystectomy), percutaneous extraction, and extracorporeal shock wave lithotripsy.
• Choledocholithiasis – found during surgery being done for cholelithiasis or cholecystitis includes intraoperative common bile duct exploration, intraoperative ERCP, and postoperative ERCP. The intraoperative procedure can be performed if consent was obtained preoperatively. Otherwise, ERCP is recommended at a later time, but during the same hospitalization.

References

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