Biliary Atresia Flashcards
What is the definition of biliary atresia?
Biliary atresia is a congenital neonatal progressive obliterative cholangiopathy, characterized by perinatal fibrosis of the bile ducts leading to the progressive obliteration of the extrahepatic bile ducts, causing biliary obstruction in the neonatal period.
What is the etiology of biliary atresia?
The etiology of biliary atresia is thought to be due to idiopathic acquired inflammatory fibrosis, potentially triggered by immune-mediated vasculitis of the bile ducts in response to perinatal viral infection. There is also a genetic susceptibility, with higher incidence in Asians. About 10% of cases are embryonic, possibly due to an unknown early neonatal embryonic insult.
How does the pathophysiology of biliary atresia resemble other conditions?
The pathophysiology of biliary atresia is similar to sclerosing cholangitis seen in adults, involving inflammatory fibrosis and progressive bile duct obstruction.
How is biliary atresia classified?
Biliary atresia is classified into four variants based on clinical homogeneity and inferred aetiological mechanisms, as the exact cause remains uncertain.
What is Biliary Atresia Splenic Malformation Syndrome (BASM)?
BASM is a variant of biliary atresia where there is a splenic malformation, often polysplenia, and a pre-duodenal portal vein is commonly encountered in affected children.
What is cystic biliary atresia?
Cystic biliary atresia is characterized by a cystic structure in the porta hepatis, with the biliary tree otherwise obliterated. This variant may be visible on antenatal ultrasound and should not be confused with choledochal malformations. It has a better outcome compared to other variants.
What is the significance of cytomegalovirus (CMV) in biliary atresia?
Some infants with biliary atresia are positive for CMV. While the exact role of CMV is uncertain, it is associated with worse outcomes following Kasai Porto-enterostomy, though causality and pathogenesis remain debated.
What is isolated biliary atresia?
Isolated biliary atresia is the most common variant, where no clear aetiological mechanism is identified. It may be a developmental issue that occurs later in fetal life, without affecting other systems or organs.
Subtypes
Anatomically, biliary atresia is subdivided into 3 types. The exact type is of
academic importance only as the surgical approach remains the same
Biliary atresia is anatomically subdivided into three types. However, the exact type is of academic importance only, as the surgical approach remains the same for all types.
What are the subtypes of biliary atresia?
Biliary atresia is anatomically subdivided into three subtypes:
1. Type I: Atresia of the common bile duct.
2. Type II: Atresia of the common hepatic duct.
3. Type III: Atresia of the extrahepatic bile ducts, the most common form.
What is the significance of the subtypes of biliary atresia?
The subtypes of biliary atresia are of academic interest, but the exact subtype does not affect the surgical approach, as treatment (e.g., Kasai Porto-enterostomy) remains the same for all types.
What is the incidence of biliary atresia?
Biliary atresia has an incidence of 1:5000 to 1:17,000, with significant regional variation. Certain types are more common in specific areas but very rare elsewhere.
When does biliary atresia typically present, and what are the initial symptoms?
Biliary atresia typically presents in term infants, usually within 2-6 weeks after birth, with increasing jaundice, progressively paler (clay-colored) stools, and dark yellow urine. There may be a history of initially normal yellow-colored stools.
What physical sign may be observed in infants with biliary atresia?
Infants with biliary atresia may develop a slightly enlarged, smooth, non-tender liver.
How is persistent pale stool confirmed in biliary atresia?
Persistent pale stools in biliary atresia can be confirmed by serial stool sampling.
What do liver function tests reveal in biliary atresia?
Liver function tests typically show conjugated hyperbilirubinaemia with a conjugated fraction >50% of total bilirubin (often 50-80%) and raised ductal enzymes (alkaline phosphatase [ALP], gamma-glutamyl-transferase [GGT]) relative to cellular enzymes.
How can a hepatobiliary ultrasound aid in diagnosing biliary atresia?
A hepatobiliary ultrasound may show an enlarged liver, oedema at the portal plate (known as the “triangular cord sign”), and a very small or invisible gallbladder. Sometimes, a cyst anterior to the portal vein in the porta hepatis may be seen. While these findings are suggestive, they are not definitive for diagnosing biliary atresia.
What is the role of a HIDA scan in diagnosing biliary atresia?
A HIDA scan, using a radio-labelled isotope, can help exclude biliary atresia if the isotope is identified in the bowel. However, it has poor positive predictive value because delayed absorption and excretion of HIDA is also seen in neonatal hepatitis.
What is the gold standard for confirming biliary atresia?
The gold standard for confirming biliary atresia is an operative cholangiogram, which should be considered in all infants with prolonged neonatal jaundice and pale stools.
What findings might a liver biopsy reveal in biliary atresia?
A liver biopsy may show cholestasis (bile duct plugs), inflammatory cells, oedema, fibrosis of portal tracts, and ductular proliferation. It can be performed open, laparoscopically, or percutaneously (usually ultrasound-guided) and helps exclude other causes of cholestasis, especially in infants who present late.
How is a cholangiogram performed in the diagnosis of biliary atresia? VP
A cholangiogram may be done laparoscopically or via open surgery, where contrast is injected into the gallbladder and imaged in the biliary tree using fluoroscopy.
What does failure of contrast to enter the duodenum or intra-hepatic biliary tree indicate?
Failure of the contrast to enter the duodenum or intra-hepatic biliary tree during a cholangiogram confirms the diagnosis of biliary atresia.
What is the goal of a Kasai portoenterostomy?
The goal of a Kasai portoenterostomy is to improve bile drainage by resecting the fibrotic extra-hepatic biliary tree and replacing it with a loop of bowel anastomosed to the liver capsule around the portal plate, allowing small biliary ductules to drain bile.
When should a Kasai portoenterostomy ideally be performed?
A Kasai portoenterostomy should ideally be performed before 60-80 days of age to improve the chances of bile drainage and liver function.
What surgical technique is used in Kasai portoenterostomy?
The surgery is performed through a right subcostal incision. The fibrotic extra-hepatic biliary tree is resected, and a loop of bowel is joined to the small bowel just below the duodeno-jejunal flexure in a “Roux-en-Y” configuration.
Who first performed the Kasai portoenterostomy?
The Kasai portoenterostomy was first performed by Japanese surgeon Morio Kasai in 1955.
What are the post-operative management steps after a Kasai portoenterostomy?
Post-operatively, prophylactic antibiotics are given for 3-6 months, a short course of high-dose steroids to improve bile drainage, and ursodeoxycholic acid for choloresis. Nutritional support is also provided as for liver failure, and life-long follow-up in a specialist hepatobiliary center is necessary.
What is the success rate of bile drainage after Kasai portoenterostomy?
Successful bile drainage, evidenced by the resolution of jaundice, is achieved in about 2/3 of patients. However, 1/3 of these patients may progress to liver cirrhosis due to established fibrosis, and may eventually require a liver transplant for long-term survival.
What are the early complications following a Kasai portoenterostomy?
Early complications may include cholangitis and infections due to immune suppression from post-operative steroids, bile leaks, anastomotic obstructions (such as strictures), wound dehiscence, incisional hernias (especially in patients with hypoalbuminaemia), and ascites which may take a few weeks to settle.
What are the late complications of a Kasai portoenterostomy?
Late complications include ascending cholangitis, which may present with high-grade fever, recurrence of jaundice, and epigastric or right upper quadrant tenderness. Prolonged broad-spectrum antibiotics may be needed for treatment.
What happens if biliary atresia is left untreated?
If untreated, biliary atresia leads to progressively worsening dark urine, acholic stools, and jaundice. Pruritus also becomes progressively worse. By 4-5 months, liver fibrosis and cirrhosis develop, and liver becomes hard and knobbly. Delayed presentation is associated with liver dysfunction complications, portal hypertension, ascites, and variceal bleeding, which can be catastrophic by around 2 years of age. End-stage liver failure and mortality from portal hypertension and liver failure occurs at 24-30 months without liver transplantation
What is the outcome of Kasai portoenterostomy if performed after 100 days of age?
The outcome of a Kasai portoenterostomy performed after 100 days of age is very poor, with less than 10% of patients achieving bile drainage. Early surgical intervention is crucial before liver cirrhosis develops
What is the ideal timing for diagnosing and performing surgery for biliary atresia?
Ideally, diagnosis and surgery should take place before the baby is 45-60 days old to improve outcomes and prevent liver cirrhosis
What happens even with early treatment for biliary atresia?
Even with early treatment, intra-hepatic fibrosis and established cirrhosis may still cause progressive deterioration of liver function, requiring a subsequent salvage liver transplant in as many as two-thirds of patients with biliary atresia.
What are the predictors of a good outcome in biliary atresia?l
Predictors of a good outcome in biliary atresia include:
• Early age at Kasai (<60 days)
• Large size of ductules on histology of the portal plate
• Minimal fibrosis or no cirrhosis on liver biopsy
• High volume centers with experienced surgeons
• Non-syndromic type
What is biliary atresia (BA)?
Biliary atresia (BA) is the most common ‘surgical’ cause of jaundice in infancy.
What is the definition of biliary atresia?
Biliary atresia is an obliterative disorder affecting both intra- and extrahepatic parts of the biliary tree, a cholangiopathy that affects all bile ducts.
What is the main surgical treatment for biliary atresia?
The main surgical treatment is radical resection of all affected extrahepatic bile ducts and reconstruction through a Kasai portoenterostomy (KPE), which involves anastomosing a Roux loop to the denuded porta hepatis.
What is the expected long-term outcome for infants with biliary atresia?
Long-term survival without the need for transplantation occurs in about 50% of infants and children with biliary atresia
