Pathology
Biliary atresia results from inflammatory and progressive destruction of bile ducts, both extra- and intrahepatic, leading to fibrosis, biliary cirrhosis, and eventual liver failure. Biliary atresia has been classified into several types depending on the location and degree of atresia . The cause of BA is unknown, but the most common form is felt to be acquired rather than congenital. Infections, intrauterine and perinatal, metabolic disorders, genetic predisposition, and environmental exposures have all been implicated as potential causes, and each may be contributory in some cases. Biliary atresia also occurs in association with a variety of other congenital anomalies. In these cases, the condition is presumed to result from abnormalities in morphogenesis and is therefore not considered an acquired lesion.
Biliary atresia results from inflammatory and progressive destruction of bile ducts, both extra- and intrahepatic, leading to fibrosis, biliary cirrhosis, and eventual liver failure. Biliary atresia has been classified into several types depending on the location and degree of atresia . The cause of BA is unknown, but the most common form is felt to be acquired rather than congenital. Infections, intrauterine and perinatal, metabolic disorders, genetic predisposition, and environmental exposures have all been implicated as potential causes, and each may be contributory in some cases. Biliary atresia also occurs in association with a variety of other congenital anomalies. In these cases, the condition is presumed to result from abnormalities in morphogenesis and is therefore not considered an acquired lesion.
Clinical Features
The most consistent clinical feature of biliary atresia is cholestatic jaundice that appears in the second or third week of life, although some infants will be jaundiced from birth. Hypopigmented or acholic stools and darkened urine are strongly suggestive of biliary atresia. An enlarged and hard liver may be evident at the time of diagnosis, and with further progression of biliary cirrhosis, splenomegaly, ascites, and bruising from coagulopathy will occur.
The most consistent clinical feature of biliary atresia is cholestatic jaundice that appears in the second or third week of life, although some infants will be jaundiced from birth. Hypopigmented or acholic stools and darkened urine are strongly suggestive of biliary atresia. An enlarged and hard liver may be evident at the time of diagnosis, and with further progression of biliary cirrhosis, splenomegaly, ascites, and bruising from coagulopathy will occur.
Evaluation and Diagnosis
The evaluation of an infant suspected of having biliary atresia is the same as that for an infant with neonatal cholestasis . Frequently, the jaundiced infants will have a mixed hyperbilirubinemia
with elevated serum alkaline phosphatase, GGT, and aminotransferase values. The absence of a gallbladder on sonography should raise suspicion of BA, although some affected infants will have a gallbladder. Radionuclide scans are often used to determine the presence or absence of biliary patency. Failure of excretion of radioisotope is an indication for liver biopsy and cholangiogram. Bile ductular proliferation and cholestasis are typical histopathologic findings; variable degrees of inflammation, giant-cell formation, and fibrosis are noted. The diagnosis of BA is confirmed by cholangiogram, usually intraoperatively but sometimes by ERCP.
Treatment and Management
The bile drainage procedure is a hepatoportoenterostomy or “Kasai procedure after Morio Kasai, who developed the operation in 1968. In this operation, a loop of intestine is attached to the porta hepatis in an attempt to reestablish bile flow from the liver. Recognition of biliary atresia and the timely establishment of biliary drainage via the portoenterostomy are critical. After 3 months of age, the liver injury may be severe enough to make portoenterostomy very unlikely to be of value. Therefore, awareness of biliary atresia and early referral for diagnostic evaluation are essential. In one-third of infants treated with portoenterostomy, jaundice never resolves, and hepatic injury progresses rapidly. In approximately another one-third, jaundice resolves over several months, but cirrhosis is already established or develops over the next several years. In these children, liver transplantation is the only other treatment option, although supportive measures such as fat-soluble vitamins, choleretic agents, and nutritional therapy are useful before transplantation. Children that have undergone a Kasai procedure are at increased risk for ascending cholangitis and therefore need prompt therapy with intravenous antibiotics if they have fever associated with increasing jaundice or other indications of worsening liver disease.
The evaluation of an infant suspected of having biliary atresia is the same as that for an infant with neonatal cholestasis . Frequently, the jaundiced infants will have a mixed hyperbilirubinemia
with elevated serum alkaline phosphatase, GGT, and aminotransferase values. The absence of a gallbladder on sonography should raise suspicion of BA, although some affected infants will have a gallbladder. Radionuclide scans are often used to determine the presence or absence of biliary patency. Failure of excretion of radioisotope is an indication for liver biopsy and cholangiogram. Bile ductular proliferation and cholestasis are typical histopathologic findings; variable degrees of inflammation, giant-cell formation, and fibrosis are noted. The diagnosis of BA is confirmed by cholangiogram, usually intraoperatively but sometimes by ERCP.
Treatment and Management
The bile drainage procedure is a hepatoportoenterostomy or “Kasai procedure after Morio Kasai, who developed the operation in 1968. In this operation, a loop of intestine is attached to the porta hepatis in an attempt to reestablish bile flow from the liver. Recognition of biliary atresia and the timely establishment of biliary drainage via the portoenterostomy are critical. After 3 months of age, the liver injury may be severe enough to make portoenterostomy very unlikely to be of value. Therefore, awareness of biliary atresia and early referral for diagnostic evaluation are essential. In one-third of infants treated with portoenterostomy, jaundice never resolves, and hepatic injury progresses rapidly. In approximately another one-third, jaundice resolves over several months, but cirrhosis is already established or develops over the next several years. In these children, liver transplantation is the only other treatment option, although supportive measures such as fat-soluble vitamins, choleretic agents, and nutritional therapy are useful before transplantation. Children that have undergone a Kasai procedure are at increased risk for ascending cholangitis and therefore need prompt therapy with intravenous antibiotics if they have fever associated with increasing jaundice or other indications of worsening liver disease.
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