Biliary Atresia

Overview

Biliary atresia is a progressive fibro-inflammatory disorder of infancy in which the extrahepatic bile ducts—and variably the intrahepatic ducts—become obliterated. This prevents bile from draining from the liver, producing conjugated hyperbilirubinaemia, progressive hepatic fibrosis and, without treatment, cirrhosis and liver failure.

Affected infants often appear well during the first weeks of life. Persistent jaundice may therefore be mislabelled as physiological jaundice or breast-milk jaundice. The most important early clues are pale or acholic stools, dark urine and persistent jaundice beyond 2 weeks of age.

Biliary atresia is a time-critical diagnosis. Early referral and Kasai hepatoportoenterostomy offer the best chance of restoring bile drainage and preserving the native liver.

Anatomy & Physiology

Bile is produced by hepatocytes and transported through:

1. Intrahepatic canaliculi and small bile ducts
2. Right and left hepatic ducts
3. Common hepatic duct
4. Common bile duct
5. Duodenum

The gallbladder stores and concentrates bile between feeds. Bile entering the intestine:

• assists fat digestion and absorption
• enables absorption of vitamins A, D, E and K
• carries bilirubin, cholesterol and other substances for excretion
• gives stool its characteristic brown colour

In biliary atresia, obstruction prevents bile from entering the intestine. Conjugated bilirubin refluxes into the bloodstream and is excreted in urine, producing dark urine. Lack of intestinal bile pigment produces pale stools. Retained bile acids injure hepatocytes and stimulate inflammation, fibrosis and progressive portal hypertension.

Aetiology & Risk Factors

Aetiology

Biliary atresia is not usually caused by failure of the ducts to form. Most evidence supports an acquired or evolving perinatal fibro-inflammatory injury in a genetically susceptible infant.

Proposed contributors include:

• dysregulated immune-mediated bile-duct injury
• abnormal ductal development or morphogenesis
• perinatal viral triggers
• genetic susceptibility
• environmental or toxic exposures

No single infectious, genetic or environmental cause explains most cases. Biliary atresia is not caused by parental behaviour, feeding practices or routine medications.

Clinical phenotypes

Isolated biliary atresia is the most common phenotype and occurs without major congenital abnormalities.

Biliary atresia splenic malformation syndrome may be associated with polysplenia or asplenia, situs abnormalities, interrupted inferior vena cava, preduodenal portal vein, intestinal malrotation and congenital heart disease.

Cystic biliary atresia may produce a cystic structure near the porta hepatis and mimic a choledochal cyst, but the intrahepatic and extrahepatic ducts do not communicate normally.

Risk factors

There are no reliable maternal or neonatal risk factors that can be used to exclude or predict biliary atresia. It usually occurs sporadically.

Pathophysiology

1. Inflammation targets the biliary epithelium.
2. Extrahepatic bile ducts become progressively damaged and replaced by fibrous tissue.
3. Bile flow from the liver to the intestine becomes obstructed.
4. Conjugated bilirubin and bile acids accumulate in the liver and bloodstream.
5. Retained bile acids cause hepatocellular injury and ductular proliferation.
6. Progressive fibrosis leads to biliary cirrhosis and portal hypertension.
7. Reduced bile delivery to the intestine causes fat malabsorption and deficiency of vitamins A, D, E and K.
8. Ongoing cholestasis, malnutrition and recurrent cholangitis accelerate liver injury.

The process may continue after technically successful Kasai surgery because the underlying intrahepatic cholangiopathy is not completely corrected.

Clinical Manifestations

Early presentation

Most infants are born at term and initially appear healthy. Typical features develop during the first weeks of life:

• jaundice persisting beyond 2 weeks
• yellow discolouration of the skin and sclera
• pale, white, grey or clay-coloured stools
• dark yellow or brown urine
• hepatomegaly
• firm liver edge
• initially preserved feeding and general appearance

Stool colour may fluctuate early in the disease. A history of occasional yellow or pigmented stools does not reliably exclude biliary atresia.

Progressive disease

• poor weight gain or growth faltering
• irritability
• abdominal distension
• splenomegaly
• ascites
• easy bruising or bleeding from vitamin K deficiency
• pruritus
• muscle and subcutaneous fat wasting
• prominent abdominal veins
• gastrointestinal bleeding from portal hypertension
• recurrent bacterial cholangitis following Kasai surgery

Features of associated congenital abnormalities

• cardiac murmur or cyanosis
• abnormal cardiac position
• splenic abnormalities
• intestinal malrotation
• abnormal abdominal organ arrangement

Diagnosis

Biliary atresia should be considered in every infant with conjugated hyperbilirubinaemia. The investigation must proceed rapidly because no single non-invasive test reliably excludes the disease and diagnostic delay may reduce the benefit of Kasai surgery.

1. Confirm cholestasis immediately

Measure total bilirubin and direct or conjugated bilirubin. A direct bilirubin concentration greater than 1 mg/dL, approximately 17 μmol/L, is abnormal and warrants evaluation, regardless of the total bilirubin concentration.

Any infant who remains jaundiced at 2 weeks should have fractionated bilirubin measured. Earlier testing is required when there are pale stools, dark urine, hepatomegaly, poor feeding, illness or another clinical concern.

2. Assess severity and identify immediately treatable causes

An elevated gamma-glutamyl transferase supports an obstructive or high-GGT cholestatic process but is not diagnostic. A prolonged INR may reflect vitamin K deficiency or impaired hepatic synthetic function. Administer parenteral vitamin K and reassess; failure to correct increases concern for significant liver dysfunction.

Undertake targeted testing for alternative treatable causes according to the presentation, particularly blood and urine cultures when infection is possible, newborn-screen results, alpha-1 antitrypsin phenotype or genotype, congenital-infection testing when indicated, and metabolic or genetic testing when the phenotype suggests another disorder. Testing for uncommon disorders should not delay biliary imaging or referral.

3. Abdominal ultrasonography

An absent, small or irregular gallbladder and a triangular-cord sign increase suspicion. However, a normal-appearing gallbladder or otherwise nondiagnostic ultrasound does not exclude biliary atresia.

4. Liver biopsy

Percutaneous liver biopsy is highly useful when the diagnosis remains uncertain and can distinguish an obstructive biliary pattern from many hepatocellular causes of neonatal cholestasis.

Features supporting biliary atresia include:

• bile-duct proliferation
• bile plugs
• portal oedema
• portal inflammation
• progressive portal fibrosis

Histology can be less typical very early in the disease and must be interpreted alongside age, stool colour, biochemistry and imaging.

5. Cholangiography

Definitive assessment of extrahepatic bile-duct patency requires cholangiography. When suspicion remains high, the infant should proceed promptly to an experienced paediatric hepatobiliary centre for operative cholangiography and Kasai hepatoportoenterostomy during the same procedure if biliary atresia is confirmed.

Failure of contrast to enter a patent extrahepatic biliary system confirms obstruction compatible with biliary atresia.

Key differential diagnoses

Differential	Distinguishing considerations
Neonatal hepatitis	Hepatocellular inflammation without extrahepatic duct obliteration; numerous infectious, metabolic and genetic causes
Alpha-1 antitrypsin deficiency	Abnormal phenotype or genotype; may closely resemble biliary atresia clinically and histologically
Choledochal cyst	Cystic biliary dilatation with demonstrable communication with the biliary tree; cystic biliary atresia may mimic it
Alagille syndrome	Cholestasis, characteristic facies, cardiac disease, butterfly vertebrae, posterior embryotoxon and paucity of intrahepatic ducts
Progressive familial intrahepatic cholestasis	Genetic cholestasis; some forms have low or normal GGT despite marked cholestasis
Congenital infection	Growth restriction, rash, thrombocytopenia, microcephaly, hearing or ocular abnormalities
Galactosaemia or tyrosinaemia	Systemic illness, hypoglycaemia, coagulopathy or metabolic abnormalities; newborn screening is important
Sepsis or urinary tract infection	Acutely unwell infant, inflammatory response and positive cultures
Cystic fibrosis–associated cholestasis	Abnormal newborn screening or sweat testing and associated pancreatic or respiratory features
Inspissated bile syndrome	Often associated with haemolysis, prematurity, parenteral nutrition or severe illness; ducts remain anatomically patent

Classification

Anatomical classification

• Type I: obstruction of the common bile duct
• Type II: obstruction at the common hepatic duct
• Type III: obstruction at the porta hepatis

Type III is the most common form.

Clinical classification

• Isolated or perinatal biliary atresia
• Biliary atresia splenic malformation syndrome
• Biliary atresia associated with other congenital abnormalities
• Cystic biliary atresia

The anatomical type is less important clinically than early diagnosis, surgical expertise, restoration of bile drainage and the severity of intrahepatic disease.

Treatment

Immediate referral

Suspected biliary atresia requires urgent referral to a centre with paediatric hepatology, paediatric hepatobiliary surgery, interventional radiology and pathology expertise, a liver-transplant pathway and specialist multidisciplinary support. Serial outpatient observation of conjugated jaundice is inappropriate.

Kasai hepatoportoenterostomy

The Kasai procedure is the initial operation for most infants without advanced irreversible liver disease. The surgeon excises the fibrotic extrahepatic biliary remnant, exposes the porta hepatis and connects a Roux-en-Y jejunal limb directly to the liver hilum, allowing microscopic residual ductules to drain bile.

The procedure should be performed as early as possible. Outcomes are generally better when surgery occurs within the first 30–60 days of life, although age alone should not automatically exclude an infant from specialist surgical assessment.

Successful bile drainage is suggested by falling serum bilirubin, return of pigmented stool, reduced jaundice and improved growth and nutritional status.

Nutritional management

• energy-dense breast milk or formula
• additional calories
• medium-chain triglycerides
• water-miscible preparations of fat-soluble vitamins
• monitoring of vitamin levels, INR and bone health
• nasogastric feeding when oral intake is inadequate
• specialist dietetic review

Weight alone may overestimate nutritional status when hepatomegaly, splenomegaly or ascites is present. Length, mid-upper-arm circumference and skinfold measurements may provide additional information.

Cholangitis

Ascending bacterial cholangitis is common after Kasai surgery. Suspect it with fever, irritability, poor feeding, recurrent or worsening jaundice, pale stools, abdominal discomfort or increasing bilirubin and liver enzymes. Obtain cultures where feasible and commence prompt intravenous antibiotics according to local microbiological guidance.

Liver transplantation

Liver transplantation is indicated when there is:

• failure to establish bile drainage after Kasai surgery
• progressive liver failure
• refractory ascites
• recurrent or severe cholangitis
• recurrent variceal bleeding
• severe portal hypertension
• hepatopulmonary syndrome
• refractory pruritus
• severe growth failure or malnutrition
• deteriorating quality of life
• hepatic malignancy

Primary liver transplantation may be considered when an infant presents late with advanced decompensated cirrhosis or when Kasai surgery is unlikely to provide meaningful benefit.

Complications & Prognosis

Complications

• Progressive biliary fibrosis and cirrhosis
• Portal hypertension
• Splenomegaly and hypersplenism
• Oesophageal or gastric varices
• Gastrointestinal bleeding
• Ascites
• Recurrent bacterial cholangitis
• Fat and fat-soluble vitamin malabsorption
• Vitamin K–deficiency bleeding
• Metabolic bone disease and fractures
• Growth failure and sarcopenia
• Pruritus
• Hepatopulmonary syndrome
• Portopulmonary hypertension
• Hepatic decompensation
• Hepatocellular carcinoma, rarely
• Need for liver transplantation

Prognosis

Outcome depends on age and liver condition at surgery, surgical expertise, restoration of bile drainage, bilirubin response after Kasai surgery, frequency of cholangitis, severity of fibrosis and portal hypertension, nutritional status and access to liver transplantation.

A substantial proportion of infants achieve useful bile drainage following Kasai surgery, allowing survival with the native liver for years or decades. However, most patients eventually develop chronic liver complications, and many require transplantation during childhood or later life.

Survival into adulthood is now expected for most children when Kasai surgery, specialist follow-up and liver transplantation are available.

References

1. Fawaz R, Baumann U, Ekong U, et al. Guideline for the evaluation of cholestatic jaundice in infants: joint recommendations of NASPGHAN and ESPGHAN. J Pediatr Gastroenterol Nutr. 2017;64(1):154–168. doi:10.1097/MPG.0000000000001334.
2. Bezerra JA, Wells RG, Mack CL, et al. Biliary atresia: clinical and research challenges for the twenty-first century. Hepatology. 2018;68(3):1163–1173. doi:10.1002/hep.29905.
3. National Institute of Diabetes and Digestive and Kidney Diseases. Biliary atresia. Accessed August 20, 2026. https://www.niddk.nih.gov/health-information/liver-disease/biliary-atresia
4. National Institute of Diabetes and Digestive and Kidney Diseases. Treatment for biliary atresia. Accessed August 20, 2026. https://www.niddk.nih.gov/health-information/liver-disease/biliary-atresia/treatment
5. Bezerra JA, Spino C, Magee JC, et al. Use of corticosteroids after hepatoportoenterostomy for bile drainage in infants with biliary atresia: the START randomized clinical trial. JAMA. 2014;311(17):1750–1759. doi:10.1001/jama.2014.2623.
6. Gu C, Sun J, Ding L, Li B, Zhang Y, Jiang G. Partial quadrate lobectomy improves early outcomes of laparoscopic Kasai surgery in type III biliary atresia. Front Pediatr. 2025;13:1541455. doi:10.3389/fped.2025.1541455.