Biliary Atresia

Definition And Epidemiology

Obliterative cholangiopathy affecting extrahepatic and intrahepatic bile ducts.
Presents in first few weeks of life with jaundice, pale stools, dark urine.
Most common cause of pediatric liver transplantation worldwide.
Incidence varies globally; 1:15,000-20,000 live births in Europe and North America, 1:5,000-10,000 in Asia.
Female predominance observed specifically in syndromic forms.

Multifactorial origin resulting in final common phenotype of biliary inflammation, luminal obliteration, and fibrosis.
Postulated mechanisms include congenital failure of bile duct development and perinatal viral or immune-mediated duct destruction.

Variant	Characteristics
Isolated Biliary Atresia	Accounts for 80-90% of cases. Typical variant. Elevated direct bilirubin at 24-48 hours implies prenatal onset.
Syndromic Biliary Atresia	Accounts for ~15% of cases. Associated with biliary atresia splenic malformation (BASM) syndrome. Features include polysplenia/asplenia, situs inversus, absent inferior vena cava, preduodenal portal vein, cardiac anomalies.
Cystic Biliary Atresia	Accounts for ~5% of cases. Obvious cyst within obliterated biliary tree. Detectable on antenatal ultrasound.
CMV IgM-Positive Biliary Atresia	Accounts for ~10% of cases. Non-Caucasian predominance, older age at diagnosis, higher aspartate aminotransferase, larger spleens, prominent CD4+ Th1+ T-cell infiltrate. Associated with poorer surgical outcome.

Type 1: Atresia of distal bile duct with patent proximal extrahepatic bile duct.
Type 2: Atresia of common hepatic duct.
Type 3: Nonpatency of entire extrahepatic biliary system and intrahepatic ducts at hilum. Comprises >95% of cases.

Healthy-appearing term infant at birth.
Conjugated jaundice persisting beyond 14 days of age.
Acholic (pale/white) stools, dark urine.
Vitamin K-dependent coagulopathy presenting as umbilical stump bleeding or catastrophic intracranial hemorrhage.
Failure to thrive, fat malabsorption, fat-soluble vitamin deficiencies (A, D, E, K).
Hepatomegaly; progression to early fibrosis and cirrhosis (ascites, splenomegaly) typically manifesting beyond 100 days of life.

Category	Specific Conditions
Medical	Neonatal hepatitis, alpha-1 antitrypsin deficiency, Alagille syndrome (paucity of interlobular bile ducts), progressive familial intrahepatic cholestasis (PFIC), congenital TORCH/CMV infections, galactosemia.
Surgical	Choledochal malformation, inspissated bile syndrome, spontaneous bile duct perforation.

Biochemistry: Conjugated hyperbilirubinemia (>1 mg/dL if total <5 mg/dL, or >20% if total >5 mg/dL), mildly raised transaminases, significantly elevated gamma-glutamyl transpeptidase (>200 IU/L), normal serum albumin.
Serum Matrix Metalloproteinase-7 (MMP-7): Highly sensitive and specific biomarker reflecting liver fibrosis severity.

Modality	Diagnostic Findings
Abdominal Ultrasonography	Excludes other surgical causes. Identifies atrophic/non-emptying gallbladder, non-visualized common bile duct. "Triangular cord sign" (fibrous tissue >3 mm anterior to portal vein bifurcation) highly suggestive. Absence of intrahepatic duct dilatation.
Hepatobiliary Scintigraphy (HIDA)	Normal hepatic uptake with failure of biliary excretion into bowel at 24 hours. High negative predictive value; visible intestinal excretion effectively rules out biliary atresia.
Percutaneous Liver Biopsy	Diagnostic accuracy 90-95%. Demonstrates bile duct proliferation, bile plugs, portal stromal edema, absence of sinusoidal fibrosis.
Intraoperative Cholangiogram	Gold standard for evaluating biliary patency. Confirms diagnosis definitively prior to resection.

Kasai Portoenterostomy (KPE): Radical excision of extrahepatic biliary remnants. Anastomosis of denuded portal plate to a 40-50 cm retrocolic Roux-en-Y jejunal loop.
Optimal Timing: Performance before 60 days of age maximizes restoration of bile flow and long-term native liver survival.

Nutritional Support: Medium-chain triglyceride-based formula to maximize caloric intake and lipid absorption. Rigorous supplementation of fat-soluble vitamins (A, D, E, K).
Corticosteroids: High-dose systemic steroids utilized to improve jaundice clearance and reduce biochemical markers of liver injury.
Ursodeoxycholic Acid (UDCA): Administered to improve biochemical liver function and promote choleresis in patients demonstrating restored bile flow.
Antimicrobial Prophylaxis: Intravenous broad-spectrum antibiotics (e.g., piperacillin-tazobactam, gentamicin) utilized to treat and prevent ascending cholangitis.

Indicated for failed KPE (persistent uncorrectable jaundice), decompensated cirrhosis, intractable portal hypertension, or severe growth failure.

Ascending Cholangitis: Occurs in 40-50% post-KPE. Features fever, acholic stools, rising bilirubin/transaminases. Requires prompt intravenous antibiotics.
Portal Hypertension: Results from progressive hepatic fibrosis. Manifests as esophageal/gastric varices, hypersplenism, ascites. Managed via endoscopic surveillance, variceal banding, or portosystemic shunts.

KPE achieves jaundice clearance in 50-60% of infants at experienced, high-volume centers.
Native liver survival is approximately 50% at 5 years post-KPE.
Overall survival reaches 93% with integrated Kasai portoenterostomy and liver transplantation programs.