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Biliary Atresia

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Key Points

  1. Biliary atresia is the most common surgical cause of cholestatic jaundice in the newborn. It is suspected based on laboratory testing demonstrating direct hyperbilirubinemia, elevated alkaline phosphatase, and gamma-glutamyl transferase.

  2. Biliary atresia is progressive inflammatory, fibrosing cholangiopathy. Ultrasonography cannot distinguish the obliterated extrahepatic biliary ducts, but can suggest the diagnosis if there is an absent or diminuitive gallbladder or a triangular cord sign.

  3. Ultimately, cholangiography is the gold standard for confirming the diagnosis of biliary atresia.

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Introduction

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Biliary atresia is a progressive sclerosis of the extrahepatic biliary tree that, if untreated, leads to cirrhosis, liver failure, and eventually death. It is the most common indication for liver transplant in children. In 1959, Kasai and Suzuki reported a new operation, hepatic portoenterostomy, which achieved biliary drainage even in infants with “noncorrectable” biliary atresia. The Kasai procedure was championed in North America by Lilly and Altman, and now the procedure is accepted worldwide as the initial surgical modality in biliary atresia.

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Pathophysiology

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Embryologically, the extrahepatic biliary tree develops from a hepatic diverticulum (liver bud) of the embryonic foregut. The distal portions of the right and left hepatic ducts develop from the extrahepatic ducts and are clearly defined tubular structures by 12 weeks of gestation. The proximal portions of the main hilar ducts derive from the intrahepatic ductal plates. These develop from fetal hepatocytes, bipotential progenitor cells, surrounding the branches of the portal vein. These primitive bile duct cells form a ring, the ductal plate, which remodels into mature bile duct structures. The process of intrahepatic bile duct development is dynamic throughout embryogenesis and continues until sometime after birth.

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Biliary atresia is classified according to the level of the biliary obstruction into 3 types: Type I—obstruction restricted to the common bile duct (CBD). Type II—obstruction of the common hepatic duct with distal patency. Type III—obstruction of the common hepatic duct and CBD (Fig. 56-1). Associated anomalies include, in about 20% of cases, cardiac lesions, polysplenia, situs inversus, absent vena cava, and a preduodenal portal vein.

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Figure 56-1

The common variants of biliary atresia: Type I (A) Distal obliteration with hilar bile cysts (formerly, “correctable” type). Type II (B) Patency of the distal biliary tree with proximal obliteration. Type III (C) Complete obliteration of the extrahepatic ducts.

Graphic Jump Location
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The pathogenesis of biliary atresia remains obscure despite numerous etiologic theories and investigations. It has been suggested that the disease is caused by (a) a failure of recanalization, (b) genetic factors, (c) defective morphogenesis, (d) ischemia/vascular lesions, (e) viruses, or (f) toxins. Currently, the most intriguing theory is that biliary atresia is the end result of 1 or more of these insults that then cause the biliary epithelium to become “upregulated” to express ...

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