(See also Overview of Biliary Function.)
Stones may be described as
Primary stones (usually brown pigment stones), which form in the bile ducts
Secondary stones (usually cholesterol), which form in the gallbladder but migrate to the bile ducts
Residual stones, which are missed at the time of cholecystectomy (evident < 3 years later)
Recurrent stones, which develop in the ducts > 3 years after surgery
In developed countries, > 85% of common duct stones are secondary; affected patients have additional stones located in the gallbladder. Up to 10% of patients with symptomatic gallstones also have associated common bile duct stones. After cholecystectomy, brown pigment stones may result from stasis (eg, due to a postoperative stricture) and the subsequent infection. The proportion of ductal stones that are pigmented increases with time after cholecystectomy.
Bile duct stones may pass into the duodenum asymptomatically. Biliary colic occurs when the ducts become partially obstructed. More complete obstruction causes duct dilation, jaundice, and, eventually, cholangitis (a bacterial infection). Stones that obstruct the ampulla of Vater can cause gallstone pancreatitis. Some patients (usually those who are older) present with biliary obstruction due to stones that have caused no symptoms previously.
In acute cholangitis, bile duct obstruction allows bacteria to ascend from the duodenum. Most (85%) cases result from common bile duct stones, but bile duct obstruction can result from tumors or other conditions (see table Causes of Bile Duct Obstruction). Common infecting organisms include gram-negative bacteria (eg, Escherichia coli, Klebsiella species, Enterobacter species); less common are gram-positive bacteria (eg, Enterococcus species) and mixed anaerobes (eg, Bacteroides species, Clostridia species). Symptoms include abdominal pain, jaundice, and fever or chills (Charcot triad). The abdomen is tender, and often the liver is tender and enlarged (possibly containing abscesses). Confusion and hypotension, abdominal pain, jaundice, and fever or chills (Reynolds' pentad) predict about a 50% mortality rate and high morbidity.
Causes of Bile Duct Obstruction
Recurrent pyogenic cholangitis (Oriental cholangiohepatitis, hepatolithiasis) is characterized by intrahepatic brown pigment stone formation. This disorder occurs in Southeast Asia. It consists of sludge and bacterial debris in the bile ducts. Undernutrition and parasitic infestation (eg, Clonorchis sinensis, Opisthorchis viverrini) increase susceptibility. Parasitic infestation can cause obstructive jaundice with intrahepatic ductal inflammation, proximal stasis, stone formation, and cholangitis. Repeating cycles of obstruction, infection, and inflammation lead to bile duct strictures and biliary cirrhosis. The extrahepatic ducts tend to be dilated, but the intrahepatic ducts appear straight because of periductal fibrosis.
In AIDS-related cholangiopathy or cholangitis, direct cholangiography may show abnormalities similar to those in primary sclerosing cholangitis (PSC) or papillary stenosis (ie, multiple strictures and dilations involving the intrahepatic and extrahepatic bile ducts). Etiology is probably infection, most likely with cytomegalovirus, Cryptosporidium species, or microsporidia.
Common duct stones should be suspected in patients with jaundice and biliary colic. Fever and leukocytosis further suggest acute cholangitis. Elevated levels of bilirubin and particularly alkaline phosphatase, alanine aminotransferase, and gamma-glutamyltransferase are consistent with extrahepatic obstruction, suggesting stones, particularly in patients with features of acute cholecystitis or cholangitis.
Ultrasonography may show stones in the gallbladder and occasionally in the common bile duct (less accurate). The common bile duct is dilated (> 6 mm in diameter if the gallbladder is intact; > 10 mm after a cholecystectomy). If the ducts are not dilated early in the presentation (eg, first day), stones have probably passed. If doubt exists, magnetic resonance cholangiopancreatography (MRCP) is highly accurate for retained stones. Endoscopic retrograde cholangiopathy (ERCP) is done if MRCP is equivocal; it can be therapeutic as well as diagnostic. CT, though less accurate than ultrasonography, can detect liver abscesses.
For suspected acute cholangitis, complete blood count and blood cultures are essential. Leukocytosis is common, and aminotransferases may reach 1000 IU/L, suggesting acute hepatic necrosis, often due to microabscesses. Blood cultures guide antibiotic choice.
If biliary obstruction is suspected, ERCP and sphincterotomy are necessary to remove the stones. Endoscopic stone fragmentation (intracorporeal mechanical or laser lithotripsy) to assist stone dissolution and clearance may be considered for stones not easily removable using standard methods (eg, an endoscopic retrieval basket or a balloon). Success rate exceeds 90%; up to 7% of patients have short-term complications (eg, bleeding, pancreatitis, infection). Long-term complications (eg, stone recurrence, fibrosis and subsequent duct stricture) are more common. Laparoscopic cholecystectomy, which is not as well-suited for operative cholangiography or common duct exploration, can be done electively after ERCP and sphincterotomy. Mortality and morbidity after open cholecystectomy with common duct exploration are higher. In patients at high risk of complications with cholecystectomy (eg, those who are older), sphincterotomy alone is an alternative.
Acute cholangitis is an emergency requiring aggressive supportive care and urgent removal of the stones, endoscopically or surgically. Antibiotics are given, similar to those used for acute cholecystitis (see Acute Cholecystitis: Treatment). An alternative regimen for very ill patients is meropenem and ciprofloxacin plus metronidazole to cover anaerobes.
For recurrent pyogenic cholangitis, management aims to provide supportive care (eg, broad-spectrum antibiotics), eradicate any parasites, and mechanically clear the ducts of stones and debris endoscopically (via ERCP) or surgically.
In developed countries, > 85% of common duct stones form in the gallbladder and migrate to the bile ducts; most are cholesterol stones.
Suspect common duct stones if patients have biliary colic, unexplained jaundice, and/or elevated alkaline phosphatase and gamma-glutamyltransferase levels.
Diagnosis is made by ultrasonography and, if inconclusive, MRCP.
ERCP and sphincterotomy should be done to remove a stone that causes obstruction.
For acute cholangitis, remove stones as soon as possible and give antibiotics.