USMLE – Choledocholithiasis
Stones in the common bile duct occur in 10-15% of patients with gallstones. These stones account for more than 80% of common bile duct stones; they migrate from the gallbladder and are similar in appearance and chemical composition to the stones found elsewhere. Primary bile duct stones may develop within the common bile duct many years after a cholecystectomy and represent the accumulation of biliary sludge consequent upon dysfunction of the sphincter of Oddi. In Far Eastern countries, where bile duct infection is common, primary common bile duct stones are thought to follow bacterial infection secondary to parasitic infections with Clonorchis sinensis, Ascaris lumbricoides or Fasciola hepatica. Common bile duct stones can cause partial or complete bile duct obstruction and may be complicated by stricture, cholangitis due to secondary bacterial infection, liver abscess and septicemia.
Choledocholithiasis may be asymptomatic or manifest as recurrent abdominal pain with or without jaundice. The pain is usually in the right upper quadrant and fever, pruritus and dark urine may be present. Painless jaundice is uncommon. Physical examination may show the scar of a previous cholecystectomy; if the gallbladder is present it is usually small, fibrotic and impalpable.
Liver function tests show a cholestatic pattern and bilirubinuria is present. If cholangitis is present the patient usually has a leucocytosis. The most convenient method of demonstrating obstruction to the common bile duct is by ultrasonography which shows dilated extra- and intrahepatic bile ducts together with gallbladder stones, but it is not always successful in indicating the cause of the obstruction in the common bile duct. Endoscopic retrograde cholangiography has the advantage that not only can a diagnosis be made of obstruction and its cause, but common bile duct stones can be removed. Percutaneous transhepatic cholangiography may also be used.
Cholangitis requires analgesia for pain, intravenous fluids and broad-spectrum antibiotics such as cefuroxime and metronidazole. Blood cultures should be taken before the antibiotics are administered. Patients require stone removal either surgically or by endoscopic sphincterotomy via ERCP. The latter is increasingly used as the first approach for the removal of bile duct stones, particularly in patients over the age of 60 years. Endoscopic sphincterotomy and stone extraction is successful in about 90% of patients and has a low morbidity and mortality. Less commonly used techniques include extracorporeal lithotripsy.
Surgical treatment of choledocholithiasis is performed less frequently because of the higher morbidity and mortality compared with an endoscopic sphincterotomy. Before exploring the common bile duct an accurate diagnosis of choledocholithiasis should be confirmed by intraoperative cholangiography or choledochoscopy. If gallstones are found, the bile duct is explored, all stones are removed, stone clearance is checked by cholangiography or choledochoscopy and a T-tube is inserted into the common bile duct.
RECURRENT PYOGENIC CHOLANGITIS (ASIATIC CHOLANGIOHEPATITIS)
This disease occurs in South-east Asia. Biliary sludge, calcium bilirubinate concretions and stones accumulate in the intrahepatic bile ducts with secondary bacterial infection. The patients present with recurrent attacks of upper abdominal pain, fever and cholestatic jaundice. Investigation of the biliary tree demonstrates that both the intra- and extrahepatic portions are filled with soft biliary mud. Eventually the liver becomes scarred and liver abscesses develop. The condition is difficult to manage and requires drainage of the biliary tract with extraction of stones, antibiotics and in certain patients, partial resection of damaged areas of the liver.