Intrahepatic duct

Outside the liver the common hepatic duct is joined by the cystic duct of the gallbladder and becomes the common bile duct (CBD). The extrahepatic and intrahepatic ducts are supplied with blood by a fine network of tiny arterial branches that originate from the hepatic and gastroduodenal arteries. As it has no other blood supply, the biliary tree is particularly susceptible to ischaemic injury, such as hepatic artery thrombosis or injury to the biliary plexus during laparoscopic surgery. This can result in extrahepatic and complex hilar and perihilar ischaemic strictures of the biliary tree. 

PSC is a chronic inflammatory disease of the biliary tree, most commonly affecting extrahepatic bile ducts involvement of intrahepatic ducts, either with extrahepatic involvement or as an isolated finding, is also possible. In contrast to PBC, PSC has a male predominance and a... 

On US a choledochal cyst will be seen as a cystic lesion with a thin wall, well defined borders, and echogenic material inside the cyst that corresponds to biliary sludge. However, it is important in the US evaluation to determine if the cyst is really a dilated choledochus, if the intrahepatic ducts are compromised, and if there is portal hypertension. As US has shown a specificity of 97% for choledochal cysts, it is widely used as the first diagnostic tool (Gubernick et al. 2000 Teele and Share 1991). 

Fig. 4.3a-e. Choledochal cyst dilatation, a-c Cystic dilatation of the CBG at successive caudad levels (type 1). d Cystic dilatation noted on 99Tc-lDA scan, e Cystic dilatation of an intrahepatic duct (type 111)... 

Since the tumor arises in the intrahepatic ducts, intrahepatic cyst, gallbladder, extrahepatic ducts, or in a choledochal cyst, jaundice will develop in 60%-80% of patients. Other manifestations include vomiting, fever, and abdominal distension (Roebuck et al. 1998). 

Serious compHcations of plastic stent placement are rare and most are related to the ERCP. Acute pancreatitis may occur in up to 5% of patients. Stenting may result in occlusion of the pancreatic sphincter due to edema or mechanical obstruction. Long stents, which extend into the intrahepatic ducts, are more likely to cause acute pancreatitis than short stents (Tamsky... 

Stent migration into the intrahepatic ducts may contribute to recurrent cholangitis or obstruction. Although this complication is rare, retrieval of a migrated stent may prove challenging. Using a variety of techniques, 80% of stents can be successfully retrieved endoscopically (Lahoti et al. 1998 O Connor 2000). (Fig. 1.11)... 

Fig. 11.7. CT of an obstructing pyloric tumour white arrow). The stomach (S) is distended and there is dilatation of the common bile duct black arrow) and some intrahepatic ducts arrowhead)...

Direct cholangiography is indicated in patients with peripheral CCA only in rare situations, i.e. to detect contralateral bile duct involvement. The mass and its satellites give the intrahepatic ducts an encased or scalloped appearance. The smooth, variable length stricture affects adjacent ducts within the same hepatic territory. This appearance is usually not mistaken for the peripherally invading Klatskin s tumour, but care is required not to interpret these findings as primary sclerosing cholangitis (PSC). 

Dibutyltin dichloride induced acute pancreatitis and bile duct lesions in rats, depending on dose (6 and 8 mg/kg body weight intravenously) and time (1-24 weeks) (Merkord Hennighausen, 1989 Merkord et al., 1997, 1999 Sparmann et al., 2001). The lesions in the pancreas developed into a pancreatic fibrosis, and the lesions in the liver into liver cirrhosis. A single intravenous administration of dibutyltin dichloride at 4 mg/kg body weight induced a mild interstitial pancreatitis after 2 days (Merkord et al., 2001). Repeated administration of dibutyltin dichloride (4 mg/kg body weight intravenously) to rats at intervals of 3 weeks induced acute interstitial pancreatitis and, after 9-12 weeks, a pancreatic fibrosis and liver lesions (intrahepatic bile duct hyperplasia) (Merkord et al, 2001). 

Primary biliary cirrhosis is characterized by progressive inflammatory destruction of the bile ducts. Immune-mediated inflammation of intrahepatic bile ducts results in remodeling and scarring, causing retention of bile within the liver and subsequent hepatocellular damage and cirrhosis. The number of patients affected with primary biliary cirrhosis is difficult to estimate because many people are asymptomatic and incidental diagnosis during routine health care visits is common. 

Melanoma of the skin Liver intrahepatic bile duct Leukemia... 

Leukemia Kidney renal pelvis Liver intrahepatic bile duct... 

The rate of resectability is only 15-20% for proximal bile duct carcinomas but up to 70% for distal lesions. In addition, there is little benefit to preoperative decompression of the biliary tree in patients having obstructive jaundice (65,66). However, this procedure is frequently practiced. For proximal cancers, local excision is often possible. In particular, hepatic resection is indicated for upper bile duct cancers with quadrate lobe invasion or unilateral intrahepatic ductal or vascular involvement, and distal and midductal lesions may require pancreatoduodenectomy. Also, biliary-enteric continuity... 

Possible increase in serum conjugated bilirubin Obstruction of bile flow commonly due to common bile duct stone or pancreatic carcinoma Failure of bile secretion Extrahepatic cholestasis Intrahepatic cholestasis... 

Primary sclerosing cholangitis is characterised by inflammation, fibrosis and destruction of the intrahepatic and/or extrahepatic bile ducts. It results in a chronic cholestatic liver disease that may lead to liver cirrhosis. Cholangiocarcinoma occurs in approximately 10-30% of patients. PSC occurs more frequently in men between the ages of 20 and 40, with a male female ratio of 2 1. It is often associated with inflammatory bowel disease, particularly chronic ulcerative colitis. 

Dilatation of both the intrahepatic and extrahepatic ducts and the common bile duct is clearly seen by ultrasound, indicating obstruction, e.g. by gallstones or tumour. 

Canaliculi enter canals of Hering in the portal triad and lead to intrahepatic bile ducts which coalesce to form the hepatic bile duct. The bile duct empties the bile into the gaU bladder which then is released into the duodenum. Bile that is excreted into the small intestine enhances nutrient uptake, protects enterocytes from oxidation, and facilitates excretion of xenobiotics and endogenous waste in the feces (Treinen-Moslen, 2001). 

Cholangiodestmctive cholestasis is caused by bile duct obstruction which may be intrahepatic or extrahepatic. Bile duct injury may lead to sloughing of epithelial cells into the lumen, cell edema, and inflammation, which may contribute to obstruction (Treinen-Moslen, 2001 Plumlee, 2004). Chronic lesions associated with cholangiodestmctive cholestasis typically include bile duct prohferation and periductular fibrosis. Vanishing bile duct syndrome, characterized by a loss of bile ducts, has been seen in chronic cholestatic disease in humans (Zimmerman, 1999 Treinen-Moslen, 2001) and has been produced experimentally in dogs (Uchida, 1989). 

---