Biliary tree obstruction

The response of the liver to any form of biliary tree obstruction induces the synthesis of ALP by hepatocytes. Some of the newly formed enzyme enters the circulation to increase the enzyme activity in serum. The elevation tends to be more notable (greater than threefold) in extrahepatic obstruction (e.g., by stone or by cancer of the head of the pancreas) than in intrahepatic obstruction and is greater the more complete the obstruction. Serum enzyme activities may reach 10 to 12 times the upper reference limit and usually return to normal on surgical removal of the obstruction. A similar increase is seen in patients with advanced primary liver cancer or widespread secondary hepatic metas-tases. Liver diseases that principally affect parenchymal cells, such as infectious hepatitis, typically show only moderately (less than threefold) increased or even normal serum ALP activities (Table 21-3). Increases may also be seen as a consequence of a reaction to drug therapy. Intestinal ALP... 

Alkaline phosphatase levels and GGT are elevated in plasma with obstructive disorders that disrupt the flow of bile from hepatocytes to the bile ducts or from the biliary tree to the intestines in condition such as primary biliary cirrhosis, sclerosing cholangitis, drug-induced cholestasis, gallstone disease, and autoimmune cholestatic liver disease. 

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... 

PTC is a technique where contrast medium is injected into the common bile duct via a needle inserted through the skin in the right upper quadrant. X-ray images are used to identify strictures or obstructions in the biliary tree. 

B9. Barber-Riley, G., The rat biliary tree during short periods of obstruction of the common duct. Am. J. Physiol. 206, 1127-1131 (1963). 

Chinese Liver Fluke. The adult worm of the Chinese liver fluke (Clonorchis sinensis) can grow to be 2 cm long. Worms infect the biliary tree where they cause local inflammation, diarrhea, and hepatomegaly in the acute infection. Progressive biliary obstruction and cirrhosis can occur in the more advanced disease state. The presence of 20—200 worms is common, but they may number over 20,000. Infection is the consequence of eating raw fish that contain viable parasites. Untreated worms can live for up to 30 years. Treatment is with praziquantil (1). 

Cholestasis is a condition characterized by impaired flow of bile, due to physical obstruction of the biliary tree or decreased bile secretion by the liver. Cholestasis produces alterations of enzyme activity in the liver (cytochrome P450) as well as altered transporter expression, with associated effects on drug clearance. As discussed previously, cholestasis can occur through inhibition of the canalicular membrane transporter, BSEP. In response to cholestasis, however, the liver has adaptive mechanisms to minimize cellular accumulation of toxic bile salts. These include upregulation of MRP3 to increase sinusoidal efflux, and downregulation of Na -taurocholate cotransporting polypeptide (NTCP), which mediates bile salt uptake from the blood to the liver. 

On percutaneous transhepatic cholangiography (PTC), extensive filling defects in the biliary tree may be seen with or without obstruction of the extrahepatic bile ducts. PTC can be performed in cases of RMS without biliary dilation and is very useful if there is an obstructive jaundice (Gazelle etal. 1998). 

Fig. 4.11a-e. Embryonal rhabdomyosarcoma of the biliary tree, a CT reveals a large mainly cystic mass. b,c Pre- and post-contrast MR images show irregular yet florid enhancement. d,e Thrombus is shown in the hepatic veins secondary to the obstructing lesion... 

Unlike treatment in the oesophagus and biliary tree, the treatment of gastroduodenal and colonic obstruction is not yet as well established. This is probably most likely due to the limited familiarity with the indications and available devices. 

If there is known or impending biliary obstruction in the presence of duodenal obstruction which needs possible stenting across the papilla an expandable metal biliary stent should be placed before the duodenal stent. The presence of a transpapillary duodenal stent may make transhepatic placement of a bihary stent more difficult and an endoscopic approach impossible. Therefore it would seem prudent to evaluate also the biliary tree in patients who are to undergo gastroduodenal stenting. 

Macroscopically CCA is a grayish-white, firm and fibrous mass because of its large amount of fibrous stroma. Characteristically this tumor has a large central core of fibrotic tissue, due to the desmoplastic reaction induced by the neoplastic cells. CCA differs from HCC since it is poorly vascularised, and the invasion of the portal tree is an infrequent complication. Hilar and bile-duct CCA grow into the walls of the bile ducts with invasion of the lumen, so obstructive jaundice and dilatation of the biliary tree are early signs. In the bile ducts, CCA presents papillary growth and periductal infiltration. Microscopically CCA represent an adenocarcinoma with its tubular or acinar-glandular structures. The neoplastic cells induce a variable desmoplastic reaction. 

Sometimes, hyperbilirubinemia without mechanical obstruction of the biliary tree is encoimtered postoperatively patients with this complication often suffer from bacterial infections and endotoxemia, which results in stimulation of Kupffer cells to secrete tumor necrosis factor-a (TNF-a) and interleukin (IL)-6. In a study by Ikeda and coworkers (Ikeda, Mitaka et al. 2003), bile was collected from rats treated with or without these cytokines. The livers, perfused with lanthanum after the injection of the cytokines, were examined ultrastructurally. In rats treated with cytokines, the total serum bile acid concentration increased and lanthanum temporarily accumulated in the bile canaliculi, which suggests that the cytokines may reduce bile canaliculi contractions and thereby decrease bile flow. 

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