#176: Before Bile Stops: Biliary Atresia

May 6, 2026 | By Vishak Venkataraman

Audio

In this episode, we break down biliary atresia from bilirubin metabolism basics and the differences between conjugated and direct bilirubin. We cover practical and novel screening tools for the primary care provider to ensure prompt diagnosis, as well as next steps for confirmatory diagnosis. We finally dive into the Kasai Procedure, which if done early, is a life saving procedure which can delay and even prevent liver transplantation. 

Biliary Atresia Pearls

1. Jaundice at > 2 weeks requires measurement with fractionated bilirubin 
2. Time is liver. Early screening and diagnosis of Biliary Atresia can prevent liver transplant 
3. If Direct Bili is > 1 mg/dl at 2 weeks, send straight to GI/hepatology urgently (days)

Biliary Atresia Notes 

Hyperbilirubinemia Basics

Bilirubin is essentially “trash” from old red blood cells

Bilirubin metabolism
Heme → Unconjugated bilirubin: When red blood cells break down, heme is converted to unconjugated bilirubin (fat-soluble form)
Transport: Unconjugated bilirubin travels through the blood to the liver
Conjugation: Inside hepatocytes (liver cells), the enzyme UGT converts it to conjugated bilirubin (water-soluble form)
Excretion: Conjugated bilirubin is pumped into bile and drains down the bile ducts (“the highway”) into the intestines
Final step: Gut bacteria convert it into pigmented stool

If bile flow is obstructed (as in biliary atresia), bilirubin cannot be excreted and builds up in the body

Conjugated vs Direct Bilirubin
Conjugated bilirubin is the “pure” form that comes from the liver
Direct bilirubin is the measurement used by majority of labs
The direct assay actually captures three things:
– Conjugated bilirubin
– A small amount of unconjugated (indirect) bilirubin
– Delta bilirubin — a form we have no true way of independently measuring
As a result, direct bilirubin measurement is slightly higher than the conjugated bilirubin measurement 

Persistent Jaundice:
Physiologic Juandice in newborns can sometimes last a few weeks.
However, according to the North American Society of Pediatric Gastroenterology (NASPHGAN), the recommendation is to collect a serum and direct bilirubin for any baby who is visibly jaundiced at 2 weeks of age or older (Fawaz, 2017). 

The primary concern for jaundice beyond 2 weeks is a problem with liver or bile ducts.
Two possible categories of dysfunction:
– Primary liver cell problem — hepatocytes themselves aren’t functioning properly
– Plumbing problem — bile isn’t draining as it should, such as biliary atresia 

Biliary Atresia Screening

What is Biliary Atresia?

A blockage of the bile ducts leading to inflammation → fibrosis (scarring) → cirrhosis → liver failure if untreated
Initially, Biliary atresia was thought of as acquired as babies looked well at birth and it wasn’t inherited. However, prenatal US did show abnormal gallbladders, and newborn babies had elevated conjugated bilirubin at birth, suggesting that the baby is born with it. 

Timing of diagnosis and treatment is critical: outcomes are significantly better when diagnosed and treated early, ideally before 4–6 weeks of age

Screening at the PCP office

In the 2 week visit/weight check, there is a quick, 3 step criteria on when to check a total and direct bilirubin.
Step 1 — Check the eyes
Look for jaundice/scleral icterus at the 2-week visit
If positive check a fractionated bilirubin

Step 2 — Think about stool color
Ask about pale or pale-yellow stools
If positive, check a direct/conjugated bilirubin

Step 3 — Review the first bilirubin
Was a direct/conjugated bilirubin checked in the newborn nursery?
If it was elevated or above the upper limit of normal, recheck it

With this information, this can be interpreted by a new database called Biliscreen.org to help PCPs streamline their evaluation.

Another opportunity to improve screening is to implement a Total and Direct Bilrubin serum screening with the Newborn Screen without an extra blood-test in the nursery. 

Disparities in Diagnosis and Screening

Known disparities exist at every step
-Who gets referred quickly
-Who gets timely imaging
–Who ultimately gets early surgery

Multiple studies show patients of color have worse outcomes due to access issues.

Disparities also exist with access to care. Not every location has access to a pediatric gastroenterologist or a hepatologist, resulting even even longer delays of diagnosis.
Biliscreen.org helps to tackle these inequities as well by providing a standard screening for all primary care provides and access to specialist service. 

Further investigations for Biliary Atresia

If after screening the direct bilirubin is greater than 1, as a PCP, the next step is to urgently refer to a Pediatric GI doctor, ideally within a few days.
Most GI/hepatology specialists will order:
-Hepatic function panel
-GGT (gamma-glutamyl transferase)
-CBC
-Abdominal ultrasound to assess for hepatic vasculature, liver, and duct anatomy

Other tests vary by specialist, but can include:
-Thyroid tests
-Alpha-1 antitrypsin phenotyping
-infectious workup
-Coagulation panel / INR
Some institutions have a feeding ultrasound (no need to fast) to assess if bile duct at the hilum of the liver is present. In addition, if the duct isn’t present, a triangular cord sign suggest duct fibrosis. 

Confirmatory testing is a cholangiogram. This can be done percutaneously with liver biopsy or intraoperatively. 

Biliary Atresia Treatment 

The Kasai Procedure (Hepatoportoenterostomy)

This is a surgical procedure where the fibrosed ducts are removed, and a loop of intestine is connected directly to the liver at the porta hepatis. As a result, the microscopic ducts in the liver can drain the bile and pressure is relieved from the liver.
Babies with the procedure done < 30 days have the best outcomes 

Early Kasai -> preservation of native liver -> possibly preventing or significantly delaying transplant

Post Kasai Management:
1) ursodiol is started to help improve bile flow
2) fat soluble vitamin supplementation (A, D, E, K)
3) Prophylactic antibiotics to prevent ascending cholangitis
4) fortified formulas and formulas with higher MCT (Medium chain Triglycerides)

The key assessment by the PCP and the hepatologist is to assess when the eyes stop being yellow.
As the child gets older, PCP needs to look for Portal Hypertension which includes GI Bleeding and Hepatosplenomegaly. If bleeding is noted, stabilize with blood and admit for variceal banding.

If Bilirubin is still elevated 3-4 months after the Kasai procedure – plan is to move forward with Liver Transplantation.

Links

https://biliscreen.org

Goal

Listeners will explain the basic pathophysiology and early screening strategies for biliary atresia, as well as the operative management with the Kasai and post-op care involved. 

Learning Objectives

After listening to this episode listeners will…  

1. Describe the bilirubin metabolism pathway from heme breakdown to intestinal excretion and explain the difference between direct and conjugated bilirubin measurements.
2. Identify the clinical signs of neonatal cholestasis including persistent jaundice and pale stool.
3. Explain the Kasai procedure, the critical importance of early surgical intervention before 4–6 weeks of life, and the essential components of post-operative management.
4. Recognize the health equity disparities that delay biliary atresia diagnosis in underserved populations as well as tools to address these gaps. 

Disclosures

Dr Harpavat reports a financial relationship with Syneos Health (Membership on Advisory Committees orReview Panels, Board Membership, etc.)
Dr. Rabbani reports no relevant financial disclosures

The Cribsiders report no relevant financial disclosures. 

Citation

Venkataraman V, Harpavat S, Rabbani T, Chiu C, Masur S. “#176: Before Bile Stops: Biliary Atresia”. The Cribsiders Podcast. https:/www.thecribsiders.com/ May 6, 2026