Diagnosing Biliary Atresia

NYU Langone specialists diagnose and treat children with biliary atresia, a rare inflammatory condition affecting newborn babies. This condition causes a blockage in the bile ducts, the narrow tubes that transport bile to the gallbladder and small intestine. Bile is a yellow-green fluid that is made in the liver, stored in the gallbladder, and carries digestive enzymes to the small intestine. Biliary atresia can’t be detected by ultrasound during pregnancy and is usually discovered shortly after birth. Its cause is unknown.

Bile has two main functions: it removes waste products from the liver and blood, and it’s a necessary part of digestion. After eating, partially digested food passes from the stomach into the small intestine, where bile helps in the digestion of fats. Bile gets to the small intestine by travelling through small ducts within the liver and then through two larger ducts outside the liver that form the common bile duct, which leads into the small intestine. 

Once there, bile helps to break down fats so that the body can make use of nutrients, such as fat-soluble vitamins. Bile also removes waste products from the liver and the blood. One waste product is bilirubin, a substance that is formed as old red blood cells decompose, releasing hemoglobin—a component of blood that carries oxygen and gives blood its red color. 

In biliary atresia, inflammation in the bile ducts may begin just before or shortly after birth, usually in the ducts located outside the liver and progressing to those inside the liver. The condition is usually only indicated after a baby is born with jaundice, a yellowing of the eyes and skin caused by a buildup of bilirubin in the blood and liver. 

Jaundice is common in newborns and usually resolves by the time the baby is two weeks old. But jaundice persists and worsens in infants with biliary atresia. Because the bile duct is inflamed and blocked, bilirubin builds up in the blood and can spill over into your baby’s urine, turning it dark yellow or brown. Too little bilirubin in the intestine makes your baby’s stools appear pale or gray. 

Having too little bilirubin in the intestine also slows a baby’s growth and development, because nutrients aren’t fully absorbed during digestion. Excess bilirubin and other waste in the liver can cause inflammation and scarring, a condition known as cirrhosis. As cirrhosis progresses, it can block blood vessels in the liver, increasing blood pressure in the vein that connects the digestive system to the liver. This condition, called portal hypertension, can cause blood vessels throughout the digestive tract to swell, rupture, and bleed. Portal hypertension can also cause a condition called ascites, in which increased pressure pushes fluid into the abdominal cavity, causing swelling and increasing the risk of infection. 

Rapid diagnosis and treatment of biliary atresia in a newborn can help to manage the condition and prevent these complications. If a baby shows symptoms, such as persistent jaundice and discolored urine and stool, NYU Langone doctors use a variety of tests to identify the cause and begin treatment as soon as possible. 

Physical Exam

During a physical exam, the doctor feels your baby’s abdomen to determine if the liver is hard and firm, which means that it is enlarged. The doctor also feels the baby’s spleen, an organ located near the stomach that purifies blood and helps the immune system attack viruses, bacteria, and other foreign substances. An enlarged spleen can signal other causes of your baby’s jaundice, such as an infection. 

Blood Tests

Some blood tests are used to look for evidence of biliary atresia. These tests measure the levels of bilirubin, which are elevated in babies with jaundice, and gamma-glutamyl transpeptidase, an enzyme that is more prevalent when bile ducts are blocked. 

Blood tests also measure the amount of time it takes for the blood to clot. In babies with biliary atresia, the liver may not produce enough vitamin K and proteins such as albumin and globulin, which are needed to form blood clots.

Another blood test looks for antibodies to viral or bacterial infections, such as toxoplasmosis, rubella, cytomegalovirus, and herpes, that can cause an enlarged liver in newborns. Another test may be used to rule out alpha-1 antitrypsin deficiency, a genetic condition that prevents the liver from making a protein that protects it from scarring. 

Abdominal Ultrasound

An abdominal ultrasound uses high-frequency sound waves to provide your child’s doctor with a view of your baby’s gallbladder and liver. A blockage in the bile ducts would prevent the flow of bile into the gallbladder, which in biliary atresia makes the gallbladder appear small and shrunken. Ultrasound may also detect an enlarged liver, which suggests a buildup of waste and fluid in that organ, or a cyst or tumor blocking a bile duct. 

Nuclear Medicine Scan 

A nuclear medicine scan of the gallbladder, also called a hydroxy iminodiacetic acid scan, is an imaging test that may be used to track the flow of bile out of the liver and into the gallbladder. In this test, a technician injects a harmless radioactive substance, also known as a tracer, into a vein in your baby’s arm. 

A special camera is positioned over the baby’s abdomen and takes pictures of the tracer as it moves through the bile ducts and into the gallbladder. 

Liver Biopsy

If ultrasound or nuclear medicine tests suggest your baby may have biliary atresia, our doctors may recommend a liver biopsy. In this test, the doctor numbs a small area of skin on your baby’s abdomen with a local anesthetic before inserting a needle to withdraw a tiny amount of liver tissue. The tissue sample is sent to a laboratory, where it is examined for signs of inflammation or scarring. Results of the biopsy are usually available within a few days. 

Exploratory Surgery

Doctors use exploratory surgery to confirm a diagnosis when evidence from blood tests, imaging tests, and a liver biopsy suggest that your baby has biliary atresia. In this procedure, performed with general anesthesia, the surgeon makes a small incision in the abdomen to look for signs of blockage in the bile ducts and damage in the liver. The surgeon may also inject a contrast dye directly into the bile duct and follow the contrast by X-ray to determine whether the bile duct is open or damaged. 

If your baby has biliary atresia, the surgeon can perform a Kasai procedure during exploratory surgery to bypass the damaged area of the liver and blocked bile ducts.

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