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Extrahepatic Biliary Atresia (BA)

Overview

  • Rare neonatal disease characterized by inflammatory obliteration of both intrahepatic and extrahepatic bile ducts.
  • Incidence: Ranges from 1 in 5000 to 1 in 12,000 live births, depending on the region.
  • Associated congenital malformations:
    • Splenic abnormalities (e.g., asplenia, double spleen).
    • Absence of the inferior vena cava (IVC).
    • Intestinal malformations.

Etiology and Pathogenesis

  • The exact mechanisms are unknown; the disease is progressive.
  • Immune-mediated inflammatory theory:
    • Proinflammatory cytokines (e.g., IL-2, IFN-γ, TNF).
    • T cells and natural killer cells found in BA.
  • Viral insult theory:
    • Possible Group C rotavirus infection leading to fibrosclerosis and obstruction of extrahepatic bile ducts.
    • Similar disease presentation in animal models.
  • HLA Association: High frequency of HLA-B12 in patients with BA.
  • Genetic association: CFC1 gene mutation linked to BA development.

Histopathology

  • Significant extrahepatic biliary obstruction.
  • Portal tract fibrosis, inflammatory cell infiltration, bile duct proliferation, and cholestasis with bile plugging.

Classification of BA

  • Based on the level of biliary obstruction:
    1. Type 1: Patency to the level of the common bile duct (CBD).
    2. Type 2: Patency to the level of the common hepatic duct.
    3. Type 3 (Most common, >90%): Involvement of the left and right hepatic ducts at the porta hepatis.

Types 1 & 2:

  • May be amenable to direct extrahepatic biliary duct–intestinal anastomosis.

Clinical Presentation

  • Symptoms:
    • Jaundice, pale stools, and dark urine shortly after birth.
    • Failure to thrive, hepatomegaly, and ascites from liver cirrhosis in advanced disease.
  • Persistent jaundice after 14 days in a term infant requires evaluation for liver disease.

Diagnostic Workup

  • Elevated conjugated bilirubin (>2.0 mg/dL).
  • Exclusionary studies:
    • TORCH panel, hepatitis B/C, α1-antitrypsin, and cystic fibrosis (CF).
    • Metabolic disorders (e.g., galactosemia, tyrosinemia).
  • Imaging:
    • Ultrasound: May reveal an atrophic or absent gallbladder.
    • Hepatobiliary iminodiacetic acid (HIDA) scintigraphy:
      • Shows absence of bile flow into the duodenum.
    • MRCP or ERCP: Defines biliary anatomy (more invasive).
  • Gold standard: Liver biopsy confirms diagnosis.
    • Findings: Portal tract fibrosis, bile duct proliferation, and bile plugging.
  • Intraoperative cholangiography is performed during operative exploration to confirm BA.

Surgical Management

Kasai Procedure (Hepatoportoenterostomy)

  • Procedure of choice.
    • Dissect extrahepatic bile ducts up to the porta hepatis (liver capsule).
    • Perform Roux-en-Y hepaticojejunostomy for reconstruction.
  • Medications:
    • Ursodeoxycholic acid and phenobarbital may promote bile drainage (efficacy uncertain).
    • Steroid therapy post-Kasai procedure (e.g., pulse therapy for cholangitis).

Postoperative Complications

  • High risk of cholangitis (45%-60%) due to intestinal bacteria colonization of bile ducts.
  • Progression to liver failure or cirrhosis may occur despite surgery, leading to the need for liver transplantation.

Outcomes

  • Kasai procedure:
    • Does not cure BA; progression occurs in >70% of cases.
    • Approximately 80% of successful Kasai patients can live up to 10 years before needing a liver transplant.
  • Liver transplantation:
    • 10-year graft survival: 73%.
    • Overall patient survival: 86%.

Key Terms Highlighted:

  • Extrahepatic Biliary Atresia (BA)
  • Proinflammatory cytokines
  • HLA-B12
  • Portal tract fibrosis
  • Type 1, 2, and 3 BA
  • HIDA scan
  • Kasai Procedure (Hepatoportoenterostomy)
  • Liver Transplantation

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