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Health condition · Clinically reviewed

Biliary atresia, the stool colour card, the split bilirubin and the Kasai.

Rare, but the leading cause of infant liver transplant in the UK. Every day before 45 days of age changes what surgery can do.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, BSPGHAN, RCPCH and the UK national supraregional centres.

  • 03

    Current for 2026

    Reflects modern UK practice including the stool colour card, centralised Kasai surgery and split-liver transplant pathways.

Key facts

Biliary atresia at a glance.

The essentials, in plain English - what it is, how rare it is and how the UK organises care.

  • What it is

    A rare progressive obliterative cholangiopathy of the newborn - fibrosis and obliteration of the extrahepatic biliary tree.

  • How rare

    Around 1 in 15,000 to 19,000 live births in the UK - the leading cause of infant cholestasis and paediatric liver transplant.

  • Types

    Type 3 (porta hepatis, around 85 per cent), Type 2 (common hepatic duct) and Type 1 (common bile duct).

  • Variants

    Isolated (around 80 per cent), syndromic BASM (biliary atresia splenic malformation, 10 to 15 per cent) and cystic BA.

  • Red flag

    Any jaundice persisting beyond 2 weeks with pale stools needs urgent split bilirubin - conjugated fraction is the key signal.

  • Treatment

    Kasai portoenterostomy at a UK supraregional centre - time-sensitive, with liver transplant if bile drainage fails.

Why this guide matters

A time-sensitive diagnosis, a centralised operation.

Biliary atresia is rare - but every day before 45 days of age matters. The three points below shape everything else on this page.

  • Prolonged jaundice is not normal

    Any baby still yellow at 2 weeks (3 weeks preterm) needs a split bilirubin - a raised conjugated fraction is the key signal.

  • The Kasai is time-sensitive

    Success rates fall from around 80 per cent before 45 days to under 40 per cent after 90 days - and are minimal beyond 120.

  • Care is centralised in the UK

    Kasai and paediatric liver transplant are nationally commissioned to King’s, Birmingham and Leeds - a rapid referral changes outcomes.

How the diagnosis is made

From a stool colour concern to a confirmed plan.

The steps a UK GP, health visitor or paediatrician will follow, in order - so parents know what to expect and why.

  1. 01

    Assessing

    Prolonged jaundice review

    Any baby jaundiced beyond 2 weeks (3 weeks if preterm) needs a formal review - the UK stool colour card in the Red Book helps parents raise the flag early.

  2. 02

    Assessing

    Split bilirubin - conjugated fraction

    The single most important test. Conjugated bilirubin above 20 micromol per litre or more than 20 per cent of total is abnormal and needs immediate workup.

  3. 03

    Assessing

    Baseline bloods and screen

    LFTs, INR, FBC, TSH, alpha-1 antitrypsin, urine culture and urinalysis, galactosaemia and amino acids to exclude metabolic mimics.

  4. 04

    Confirming

    Ultrasound of the liver

    Looks for the triangular cord sign, an absent or small gallbladder and features of BASM such as polysplenia or a preduodenal portal vein.

  5. 05

    Confirming

    HIDA scan and liver biopsy

    HIDA shows no excretion into the bowel at 24 hours. Percutaneous liver biopsy shows bile ductular proliferation, portal fibrosis and bile plugs.

  6. 06

    Preparing

    Referral to a supraregional centre

    Urgent transfer to King’s College Hospital, Birmingham Children’s Hospital or Leeds Teaching Hospitals - the three UK nationally commissioned centres.

  7. 07

    Preparing

    Intraoperative cholangiogram

    Laparoscopy with an on-table cholangiogram is the confirmatory test where imaging is inconclusive - and sets up the Kasai in the same theatre visit.

Typical timeline: from prolonged jaundice review to Kasai in days, not weeks.

Symptoms

What biliary atresia looks like in a baby.

Babies are normal at birth. The picture builds over the first weeks - jaundice that will not fade, pale stools, dark urine and a growing liver.

  • Persistent jaundice beyond 2 weeks

    A baby who is still yellow at 2 weeks (or 3 weeks if preterm) needs a split bilirubin - do not assume physiological jaundice.

  • Conjugated hyperbilirubinaemia

    A raised conjugated (direct) fraction is the key laboratory signal - it separates biliary atresia from harmless breast-milk jaundice.

  • Pale, acholic stools

    Chalky, putty-coloured stools mean bile is not reaching the bowel. Compare to the UK stool colour card in the Red Book.

  • Dark urine

    Water-clear urine is normal in a young baby - tea-coloured or dark urine is not, and points to a conjugated bilirubin leak.

  • Hepatosplenomegaly

    A firm, enlarged liver, sometimes with a palpable spleen, reflects developing fibrosis and portal hypertension.

  • Poor weight gain and failure to thrive

    Fat malabsorption from missing bile and fat-soluble vitamin deficiency slow growth and blunt feeding.

  • Bruising or bleeding

    Vitamin K deficiency from cholestasis can cause coagulopathy and intracranial bleeding - a well baby can decompensate suddenly.

  • Red flag - BASM features

    Polysplenia, situs inversus, a preduodenal portal vein, interrupted IVC or cardiac lesions all point to syndromic biliary atresia.

Treatment

How biliary atresia is treated in the UK.

Rapid referral, a time-sensitive Kasai portoenterostomy at a national centre, and a plan for lifelong follow-up or transplant when needed.

  • Early referral by 6 weeks

    The single biggest determinant of outcome. Any suspected cholestasis needs same-week specialist paediatric hepatology input.

  • Kasai portoenterostomy

    Surgical mainstay - excision of the extrahepatic biliary remnant with a Roux-en-Y jejunal loop anastomosis to the porta hepatis.

  • UK supraregional centres

    Nationally commissioned care at King’s College Hospital London, Birmingham Children’s Hospital and Leeds Teaching Hospitals only.

  • Prophylactic antibiotics

    Cotrimoxazole after Kasai reduces the risk of ascending cholangitis in the reconstructed biliary loop.

  • Ursodeoxycholic acid (UDCA)

    Helps bile flow and protects hepatocytes after surgery, alongside careful nutritional support.

  • Fat-soluble vitamins and MCT feeds

    Vitamins A, D, E and K plus high-calorie medium-chain triglyceride feeds counter fat malabsorption and support growth.

  • Cholangitis management

    Any post-Kasai fever with rising bilirubin is treated as ascending cholangitis - urgent hospital admission and IV antibiotics.

  • Liver transplantation

    For failed drainage or progressive cirrhosis - split-liver, reduced-size and living-donor options at the specialist paediatric centres.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, specialist society standards and family-facing resources, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP, health visitor or paediatric team knows your baby and can tell you which parts apply. If in doubt, get seen.

  • NICE. Neonatal jaundice: assessment and management (CG98).

  • BSPGHAN. Position statement on the investigation of prolonged neonatal jaundice.

  • RCPCH. Personal Child Health Record (Red Book) - stool colour card.

  • NHS England. National service specification for paediatric hepatology and liver transplantation.

  • Children’s Liver Disease Foundation (CLDF). Family information on biliary atresia and Kasai.

Red flags

When a baby with jaundice needs urgent review.

Most neonatal jaundice is harmless. These are the signs that are not, and where a same-day paediatric review is needed.

  • Jaundice beyond 2 weeks

    Any full-term baby still visibly yellow at 2 weeks (or 3 weeks if preterm) needs a same-week split bilirubin, not reassurance.

  • Pale stools and dark urine

    Chalky stools with dark urine in a young baby is biliary atresia until proven otherwise - do not wait for a routine appointment.

  • Bruising or unexplained bleeding

    Vitamin K deficiency from cholestasis can cause serious intracranial bleeding in an otherwise well-looking baby.

  • Fever after Kasai

    Post-Kasai fever with rising bilirubin is treated as ascending cholangitis - hospital assessment and IV antibiotics, same day.

  • BASM features

    Polysplenia, situs inversus, cardiac defects or a preduodenal portal vein point to syndromic disease and change surgical planning.

  • Failure to thrive

    Poor weight gain in a jaundiced baby signals fat malabsorption and needs specialist dietetic input alongside investigation.

  • Progressive abdominal distension

    A tense abdomen with visible veins or ascites reflects portal hypertension and needs urgent hepatology review.

  • Variceal bleeding

    Haematemesis or melaena in a child with a native liver after Kasai is a hepatology emergency.

  • Parental concern trumps a normal look

    A parent worried about persistent yellowing or stool colour deserves a split bilirubin - the earlier the diagnosis, the better the Kasai outcome.

Living with it

A rare condition, with a clear pathway.

Four things that make the biggest difference in the first months and years - speed to Kasai, nutrition, vigilance for cholangitis and family support.

A quiet reminder

Around 30 to 40 per cent of children reach adulthood with their native liver.

For the rest, split-liver, reduced-size and living-donor transplants at the specialist paediatric centres offer excellent long-term outcomes.

  1. 01 Time

    Every day counts before Kasai

    Success rates fall from around 80 per cent before 45 days to under 40 per cent after 90 days - and are minimal beyond 120.

  2. 02 Nutrition

    Feed for growth, not just calories

    High-calorie MCT feeds and fat-soluble vitamin supplements are as important as the surgery itself.

  3. 03 Watch

    Know the signs of cholangitis

    Fever, worsening jaundice or pale stools after Kasai always need urgent hospital review.

  4. 04 Support

    You are not alone

    The Children’s Liver Disease Foundation (CLDF) and your specialist nurse are there for the long haul - use them.

Frequently asked

Everything parents ask about biliary atresia.

Quick answers on prolonged jaundice, the split bilirubin, the Kasai and what happens if it does not work.

  • What is biliary atresia?

    A rare progressive obliterative cholangiopathy of the newborn in which the extrahepatic bile ducts become fibrosed and obstructed. Bile cannot escape from the liver, and without surgery it is the leading cause of infant cirrhosis and paediatric liver transplant in the UK.

  • How common is it and who gets it?

    Biliary atresia affects around 1 in 15,000 to 19,000 UK live births. About 80 per cent of babies have the isolated form, 10 to 15 per cent have syndromic BASM (with polysplenia, situs inversus, a preduodenal portal vein, interrupted IVC or cardiac lesions), and a small number have cystic biliary atresia.

  • What are the early signs I should watch for?

    A baby who is still jaundiced beyond 2 weeks (3 weeks if preterm), with pale putty-coloured stools, dark urine and sometimes poor weight gain. The UK Red Book stool colour card is designed to catch this early. Any of these together deserves a same-week split bilirubin.

  • How is the diagnosis confirmed?

    A split bilirubin first - a raised conjugated fraction is the key laboratory signal. Then an ultrasound (looking for the triangular cord sign and BASM features), a HIDA scan showing no bowel excretion, and a liver biopsy. Laparoscopy with an on-table cholangiogram is the confirmatory test and sets up the Kasai operation.

  • What is the Kasai operation?

    A Kasai portoenterostomy removes the fibrosed extrahepatic biliary remnant and joins a loop of small bowel (a Roux-en-Y jejunal loop) directly to the porta hepatis so bile can drain. It is time-sensitive - success rates are around 80 per cent when performed before 45 days of age and fall sharply after 90 days. In the UK it is centralised to three supraregional centres - King’s College Hospital London, Birmingham Children’s Hospital and Leeds Teaching Hospitals.

  • What if the Kasai does not work?

    Around 30 to 40 per cent of children reach adulthood with their native liver. If bile drainage is not established or cirrhosis and portal hypertension progress, liver transplantation is offered - split-liver, reduced-size and living-donor options are all used at the specialist paediatric centres. Long-term follow-up covers portal hypertension, varices, fat-soluble vitamins, growth, development and psychological support.

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