Biliary atresia !
- Malformation
The ducts that carry bile out of the liver inflame and close in the first weeks of life: jaundice that does not fade and very pale stools.
Updated 2026-11-01
See it in 3D: Common bile duct · Common hepatic duct · Cystic duct · Gallbladder · Liver · Portal vein
What it is
It is a progressive fibro-obliterative cholangiopathy of the extrahepatic and later intrahepatic bile ducts of infants that blocks bile outflow. It is not simply a failure of recanalization: current thinking is a developmental vulnerability, sometimes with laterality defects, followed by an inflammatory or viral injury after birth. Without early surgery it leads to cirrhosis, and it is a leading reason for liver transplantation in children.
Embryological cause
- Isolated form, the most common: the biliary tree forms but undergoes progressive inflammatory obliteration around birth.
- Two-hit model: a developmental vulnerability (abnormal ductal plate remodelling, possible ciliopathy) plus a postnatal immune or viral injury (CMV in a subgroup).
- Syndromic form: an early developmental defect tied to laterality, with a splenic malformation.
- The obliterated duct remains as a fibrous cord at the porta hepatis.
How it presents
- Jaundice that appears or persists after the second week in an infant who at first looks well.
- Increasingly pale stools and dark urine.
- Firm hepatomegaly; later splenomegaly, ascites and poor growth from cirrhosis.
- Bleeding from vitamin K deficiency due to fat malabsorption.
- Associations: polysplenia, heterotaxy, preduodenal portal vein, interrupted inferior vena cava and malrotation.
Diagnosis
- Raised direct bilirubin; prolonged infant jaundice is investigated with fractionated bilirubin.
- Fasting ultrasound: triangular cord and a small or absent gallbladder.
- Hepatobiliary scan: no excretion into the bowel; if tracer reaches the bowel, biliary atresia is ruled out.
- Liver biopsy and intraoperative cholangiography confirm the diagnosis.
Test yourself
Think of the answer, then tap the question to see it.
Which bilirubin fraction is raised in biliary atresia?
Direct or conjugated bilirubin, because the liver conjugates it but cannot excrete it through the bile ducts.
Which ultrasound sign is characteristic?
The triangular cord: an echogenic fibrous remnant at the porta hepatis.
Why does early surgery matter?
Because the Kasai portoenterostomy works best before 60 days; after that fibrosis progresses toward cirrhosis.
Which anomalies are associated with the syndromic form?
Polysplenia, situs inversus, preduodenal portal vein, interrupted inferior vena cava, malrotation and heart defects.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Liver, gallbladder and pancreas
- Mesenteries, the omental bursa and the spleen
- Malrotation and midgut volvulus
- TORCH infections: what each agent does to the embryo and fetus
Related conditions
Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.
Sources: Biliary Atresia (StatPearls Publishing (NCBI Bookshelf), 2026); Biliary atresia (MedlinePlus, U.S. National Library of Medicine, 2026).
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Representative model, for educational purposes only.