Biliary atresia refers to progressive destruction of the extrahepatic biliary system.
Biliary atresia presents exclusively in the neonatal period with biliary obstruction. It is due to progressive destruction of the extarhepatic biliary system. The cause is idiopathic and may be associated with other congenital malformations.
It is the most common reason for surgical intervention in neonatal jaundice and the most common cause of liver transplantation in children. The incidence is around 1 in 10,000-20,000 live births.
Without surgical intervention to fix the obstruction, the condition is invariably fatal.
The cause of biliary atresia is idiopathic.
Biliary atresia is a phenotype that can occurs due to a variety of injuries to the biliary system of the fetus during development or the perinatal period. The cause is idiopathic, but there are some suspected underlying aetiological factors including viral, genetic, toxic and immune-mediated.
Biliary atresia can be further classified based on biliary anatomy, clinical presentation or association with other abnormalities.
The Ohi classification divides the types of biliary atresia into three groups based on anatomy. These can be further subdivided based on proximal and distal anatomical features of the biliary tree.
Several congenital malformations may associate with biliary atresia including situs inversus, asplenia, intestinal atresia, or imperforate anus to name a few. Newborns with other congenital malformations are more likely to have an embryonic form of biliary atresia and present with jaundice at birth.
Biliary atresia presents with jaundice, which can occur any time from birth to 8 weeks.
Biliary atresia is a classic ‘surgical’ cause of neonatal jaundice. It is unlikely to appear after 8 weeks.
A definitive diagnosis of biliary atresia is made by an intraoperative cholangiogram showing biliary obstruction.
Biliary atresia is a cause of prolonged jaundice, which is jaundice occurring for >14 days. The key investigation is split bilirubin, which looks at both the conjugated and unconjugated components. Conjugated bilirubin (i.e. direct bilirubin) is a marker of biliary obstruction, which is seen in biliary atresia.
Investigations confirm conjugated hyperbilirubinaemia and screen for other causes:
If biliary atresia is suspected a series of additional investigations are needed to confirm the diagnosis:
NOTE: a cholangiogram is usually performed intraoperatively. It guides the decision for surgical management.
The initial management of biliary atresia is a hepatoportoenterostomy, known as the Kasai procedure.
The Kasai procedure aims to restore bile flow from the biliary system to the intestines. A roux-en-Y loop of small intestine is anastomosed directly to the hilum of the liver after excision of the remnant biliary system. The proximal end of the intestine at the point of excision is then rejoined side-on.
NOTE: a roux-en-Y loop is a typical general surgical procedure. It involves cutting a point in the small bowel. The distal end is dragged up and connected to a proximal organ (e.g. stomach, liver). The proximal end is rejoined to the intestine side-on.
A Kasai procedure should be performed within 45-60 days of life. The majority of patients will ultimately require a liver transplantation due to slowly progressive liver disease. At least 50% will need a liver transplant by two years old.
The combination of Kasai procedure and liver transplantation means >90% survive into adulthood.
It is estimated that 60-80% of patients with biliary atresia will ultimately need a liver transplantation. The main indications for transplant include portal hypertension, progressive liver dysfunction and/or growth failure.
The five-year survival for liver transplantation after two years old is estimated at 97%.
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