Types of Biliary Atresia

Biliary Atresia is a condition in which the normal extrahepatic biliary system is disrupted progressive damage of extrahepatic and intrahepatic bile ducts secondary to inflammation may occur, leading to fibrosis, biliary cirrhosis, and eventual liver failure affects approximately 1 in 10,000-15,000 births and occurs in 2 distinct forms: fetal-embryonic and postnatal.

Forms of BA The fetal-embryonic form/ Syndromic BA (10-35%) appears in the first 2 weeks of life In this form, the bile ducts are discontinuous at birth, and 10-20% of affected neonates have associated congenital defects, including situs inversus, polysplenia, malrotation, intestinal atresia, and cardiac anomalies, among others. The post/perinatal form/ Non-syndromic BA (65-90%) This form is typically found in neonates and infants aged 2-8 weeks Progressive inflammation and obliteration of the extrahepatic bile ducts occur after birth An isolated anomaly and infants may have a short jaundice-free interval

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Classification of BA The French classification is based on the anatomical pattern of the extrahepatic biliary tract remnant.

French Classification TYPE 1: (3%) Atresia limited to common bile duct TYPE 2: (6%) Cyst in the liver hilum communicating with "hairy" intrahepatic bile ducts TYPE 3: (19%) Gallbladder, cystic duct and common bile duct patent Type 4: (72%) Complete extrahepatic biliary atresia Several surgical classifications of BA cases have been proposed. The French classification is based on the anatomical pattern of the extrahepatic biliary tract remnant  Type 1 (3%): Atresia limited to common bile duct Type 2 (6%): Cyst in the liver hilum communicating with "hairy" intrahepatic bile ducts Type 3 (19%): Gallbladder, cystic duct and common bile duct patent Type 4 (72%): Complete extrahepatic biliary atresia

Classification of BA The Kasai Classification System Most widely used Divides cases of biliary atresia according to their location and degree of pathology

Kasai Classification TYPE 1: CBD is obliterated proximal bile ducts are patent TYPE 2: atresia of the hepatic duct is seen, cystic bile ducts at porta hepatis TYPE 2A: cystic and CBD are patent TYPE 2B: cystic, CBD and hepatic ducts are all obliterated Type 3: atresia refers to discontinuity of both R and L hepatic ducts to the level of the porta hepatis common, ( >90% of cases) Classification of biliary atresia according to the location of involvement (gray areas). Type I is obliteration of the common bile duct while the proximal bile ducts are patent. Type II, atresia of the hepatic duct is seen, with cystic bile ducts found at the porta hepatis.  Type IIa is atresia of the hepatic duct with cystic bile ducts found at the porta hepatis (the cystic and common bile ducts are patent). Type IIb is atresia of the cystic duct, common bile duct, and hepatic ducts (the cystic, common bile duct and hepatic ducts are all obliterated). Type III is involvement of the extrahepatic biliary tree and intrahepatic ducts of the porta hepatis (discontinuity of both right and left hepatic ducts to the level of the porta hepatis). type III biliary atresia is common, accounting for >90% of cases.

Classification of BA Type 1 (~3%) Atresia limited to common bile duct French classification Frequency Description Upper level of obstruction of the extrahepatic bile ducts US/UK/Japan classification (Kasai) Type 1 (~3%) Atresia limited to common bile duct Common bile duct Type 2 (~6%) Cyst in the liver hilum communicating with dystrophic intrahepatic bile ducts Hepatic duct Type 3 (19%) Gallbladder, cystic duct and common bile duct patent Porta hepatis Type 4 (72%) Complete extrahepatic biliary atresia