Biliary Atresia Dr. Altan Alim Yeditepe University Medical Faculty Section of Organ Transplantation and Pediatric Surgery

Introduction Secondary biliary cirrhosis Biliary atresia is characterized by obliteration or discontinuity of the extrahepatic biliary system, resulting in obstruction to bile flow. Most common surgically treatable cause of Cholestasis in newborns If not corrected  Secondary biliary cirrhosis

Embryology The biliary system originates from the hepatic diverticulum of the foregut at 4 weeks’ gestation. This differentiates into cranial and caudal components, which give rise to the intrahepatic and extrahepatic bile ducts, respectively.

Groups Isolated Biliary Atresia Associated with  situs inversus or polysplenia/asplenia with or without other congenital anomalies Postnatal form Fetal /embryonic form Accounts for 65-90% of cases 10-35% of cases.

Kasai classification system Type I obliteration of the common bile duct the proximal ducts are patent Type II Type IIa is atresia of the hepatic duct, with cystic bile ducts found at the porta hepatis Type IIb is atresia of the cystic duct, common bile duct, and hepatic ducts

Should not be confused with intrahepatic biliary hypoplasia, Type III >90% of patients atresia occurs at porta hepatis. Should not be confused with intrahepatic biliary hypoplasia, Group of distinct and surgically noncorrectable disorders.

Variants of ductal anatomy in biliary atresia

Pathophysiology/Etiology Multifactorial Genetic Inflammatory infectious Infectious agents causing bile duct obliteration (H/P evidence of inflammatory lesion) reovirus type 3 rotavirus and  cytomegalovirus (CMV)

Pathophysiology/Etiology Other causes include bile duct ischemia, abnormal bile acid metabolism, pancreaticobiliary maljunction environmental toxins

Congenital Anomalies Associated with Biliary Atresia Malrotation Preduodenal portal vein Polysplenia Interrupted inferior vena cava Azygous continuation Cardiac malformations

Epidemiology Highest in Asian populations Biliary atresia occurs in between 1 in 10,000 and 1 in 16,700 live births More common in females than in males Long -term survival rate for infants with biliary atresia following portoenterostomy 47-60% at 5 years 25-35% at 10 years The fetal/perinatal form is evident within the first 2 weeks of life. The postnatal type presents in infants aged 2-8 weeks.

Diagnosis History jaundice, dark urine, and light stools. In most cases, acholic stools are not noted at birth but develop over the first few weeks of life. Appetite, growth, and weight gain may be normal during the first few weeks of life.

Physical findings Hepatomegaly may be present early, and the liver is often firm or hard to palpation.  Splenomegaly is common, Enlarging spleen suggests progressive cirrhosis with portal hypertension In fetal/neonatal form (polysplenia/asplenia syndrome), midline liver may be palpated in the epigastrium . Cardiac murmurs  associated cardiac anomalies

Work Up Labs Serum bilirubin (total and direct) infants show only moderate elevations in total bilirubin, which is commonly 6-12 mg/dL, with the direct fraction comprising 50-60% of total serum bilirubin. Alkaline phosphatase (AP), 5' nucleotidase, gamma-glutamyl transpeptidase(GGTP), serum aminotransferases, serum bile acids Serum alpha1-antitrypsin with Pi typing: Alpha1-antitrypsin deficiency is the most common inherited liver disease that presents with neonatal cholestasis. Sweat chloride (Cl): Biliary tract involvement is a well-recognized complication of cystic fibrosis (CF)

Imaging studies Ultrasonography  Exclude specific anomalies of the extrahepatic biliary system, particularly choledochal cysts. In biliary atresia it may demonstrate absence of the gallbladder and no dilatation of the biliary tree. sensitivity and specificity do not exceed 80%

Gallbladder ghost triad gallbladder length less than 1.9 cm, a thin or indistinct gallbladder wall, an irregular and lobular contour 97% sensitive and 100% specific for biliary atresia.

Hepatobiliary scintiscanning using technetium-labeled diisopropyl iminodiacetic acid (DISIDA) nuclear scintiscan, intestinal excretion of radiolabel confirms patency of the extrahepatic biliary system. If time allows, all jaundiced infants undergoing hepatobiliary scintigraphy should be pretreated with phenobarbital (5 mg/kg/day) for 5 days before the study. sensitivity of hepatobiliary scintigraphy is high (~100%). The specificity is  93% specific, and 94.6% accurate in diagnosing biliary atresia following pretreatment with phenobarbital

disadvantages reliability of the scintiscan is diminished at very high conjugated bilirubin levels (>20 mg/dL). 10% rate of false-positive or false-negative diagnostic errors

MRCP incomplete visualization of the extrahepatic biliary system sensitivity and specificity of 90% and 77%, respectively.

Endoscopic retrograde cholangiopancreatography (ERCP) Percutaneous liver biopsy most accurate nonsurgical diagnostic test differentiate between obstructive and hepatocellular causes of cholestasis, with 90% sensitivity and specificity for biliary atresia bile ductular proliferation in the liver biopsy is considered diagnostic for biliary atresia Intraoperative cholangiography: demonstrates anatomy and patency of the extrahepatic biliary tract. 

Management Surgical intervention is the only mechanism for a definitive diagnosis (intraoperative cholangiogram) therapy (Kasai portoenterostomy).

When to operate Goal is to operate before 70 to 90 days of life. It is important to note, however, that hepatic portoenterostomy is not contraindicated after 90 days of age. A study of older children (100 days) revealed acceptable survival rates, supporting the use of the procedure, if possible, even in older infants