BILIARY ATRESIA (BILIARY TRACTOR ATRESIA)

Biliary atresia is the most important and common cause of jaundice requiring surgical intervention in children. The exact cause is unknown. It is seen in one in 10,000-25,000 live births.
Embryology
Bile ducts develop as caudal and cranial parts from the hepatic diverticulum of the foregut in the 4th week of embryological life. The gallbladder, cystic duct and common bile duct develop from the caudal part, and intrahepatic bile ducts and proximal extrahepatic bile ducts develop from the cranial part. Bile ducts, which are initially a solid cord, become tubular from the 7th week, and bile begins to flow into the ducts from the 3rd month. When biliary atresia is mentioned, a congenital anomaly of the bile ducts that causes an obstructive type of jaundice as a result of a dynamic, progressive, sclerosing process involving both extrahepatic and intrahepatic bile ducts should come to mind.
Etiology
Recanalization insufficiency
Ischemic damage: Vascular insufficiency during the development of the embryo
Toxic. damage:
Infectious causes: Association with Reovirus Type III

Early embryological development anomaly: Additional anomalies such as polysplenia and preduodenal portal vein are encountered in 10-15% of cases
Although different etiological reasons such as have been suggested and shown in some cases, the exact cause is not yet known.
Classification
The structure of extrahepatic bile ducts in biliary atresia can be in 3 ways:
All extrahepatic bile ducts atresia. This type accounts for 80% of the cases.
Common hepatic duct atresia. In these cases, the common bile duct is open.
Common bile duct atresia.
Histopathology:

It is a dynamic event with progressive obstruction. Microscopically, the distal main channels are completely obliterated and replaced by a dense fibrous scar. The more proximal bile ducts are surrounded by concentric periductal fibrosis. Fibrotic obstruction of the extrahepatic ducts increases in proportion to the age of the patient, and fibrosis in the liver also progresses progressively. Over time, fibrous tissue extends to the hepatic septa and separates the liver lobules. In this case, micronodular cirrhosis develops. This event occurs within a period of 6 months.
While there is only a sign of cholestasis at the beginning of the event, bile canalicular proliferation, periportal fibrosis and biliary cirrhosis develop in the later period. This progressive sclerosing process in biliary atresia shows a panductal feature involving all extra and intrahepitic bile ducts.
Clinical

There is a clinic of obstructive type jaundice. Jaundice usually begins from the 3rd week after birth. These babies may be normal at birth and their stools may even be normal in color. This is because bile pigments in fetal blood It is excreted by passing to the mother through the placenta. Later, these babies become icteric and their stools become acolic. These babies are in good general condition except for jaundice. Their nutrition and weight gain are normal. During physical examination, the skin and sclera are found to be icteric.
Diagnosis

If jaundice exceeds 7 days in term babies and 15 days in premature babies and there is an increase in direct bilirubin, it is not possible to accept this as prolonged physiological jaundice. In this case, hepatocellular diseases that may cause jaundice should be investigated. These include TORCH group diseases (Toxoplasma, Rubella, Cytomegalovirus, Herpes and Syphilis), neonatal hepatitis, alpha 1 antitrypsin deficiency, metabolic diseases, cystic fibrosis. In biliary atresia, the total serum bilirubin value, where direct hyperbilirubinemia is evident, is usually 15-20mg/dl. There is no stercobilin in the feces. Urine urobilinogen decreased and bilirubin amount increased. Elevated alkaline phosphatase is evident.
Differential Diagnosis
The most frequently involved disease is neonatal hepatitis. Other diseases are
Metabolic Diseases: Alpha 1 antitrypsin deficiency, galactosemia, fructosemia, tyrosinemia, cystic fibrosis,
Infectious Diseases: TORCH group, Neonatal Hepatitis

Anatomical: Choledochal cyst, idiopathic bile duct perforation, biliary hypoplasia, bile plug syndrome, Alagille Syndrome
Other: Hemolytic diseases, sepsis, TPN, pyloric stenosis, intestinal atresia, hypothyroidism
Biliary atresia is a disease most often confused with neonatal hepatitis. Ultrasonography and Tc 99m IDA scintigraphy are the most appropriate approach for diagnosis and differential diagnosis. In early cases, scintigraphy can help in the differential diagnosis from neonatal hepatitis. However, in delayed cases, scintigraphy is inadequate for differential diagnosis. In this case, exploratory laparotomy and per operative cholangiography are required for a definitive diagnosis. CT and MRI have no place in the diagnosis of biliary atresia. Periportal fibrosis, bile duct proliferation and the appearance of bile plugs within the canaliculi in per-cutaneous liver biopsy are also findings in favor of biliary atresia.
Treatment

In cases where biliary atresia is suspected, exploratory laparotomy should be performed quickly without wasting too much time with diagnostic procedures, and if the diagnosis is certain, corrective surgery should be performed on the patient at the same time. In surgical treatment, hepatic portoenterostomy surgery, which was first described by Kasai in 1968 and recorded in the literature as Kasai surgery, is performed. In hepatic port enterostomy, a jejunum segment is opened in the form of Roux-en-Y to ensure the flow of bile from the open bile canaliculi in the port hepatis to the intestine. The success of this surgery depends on the age of the patient at the time of surgery and the size of the bile canaliculi in the porto hepatis. The success rate of Kasai surgery performed within the first 2 months after birth is reported to be 70%. The success rate of surgery performed on patients older than 4 months is quite low due to cirrhosis developing in delayed cases.
Complications of Kasai surgery:
Cholengitis
Bile stasis
Portal Hypertension
Cirrhosis

In cases where Kasai surgery fails or in cases that arrive late, the other treatment option is liver transplantation.