Biliary atresia
| Biliary atresia | ||
| ICD-10 | Q44.2 | |
|---|---|---|
| ICD-9 | 751.61 | |
| OMIM | 210500 | |
| DiseasesDB | 1400 | |
| MeSH | C06.130.120.123 | |
|
Biliary atresia Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Biliary atresia On the Web |
|
American Roentgen Ray Society Images of Biliary atresia |
For patient information, click here
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Assosciate Editor(s)-In-Chief: Prashanth Saddala M.B.B.S
Synonyms and keywords: Extrahepatic ductopenia, Progressive obliterative cholangiopathy, Atresia of bile ducts
Overview
Biliary atresia, is a congenital or acquired disease of the liver and one of the principal forms of chronic rejection of a transplanted liver allograft.
In the congenital form, the common bile duct between the liver and the small intestine is blocked or absent.
The acquired type most often occurs in the setting of autoimmune disease, and is one of the principal forms of chronic rejection of a transplanted liver allograft.
Classification
There are three main types of extrahepatic biliary atresia:-
- Type I: atresia restricted to the common bile duct.
- Type II: atresia of the common hepatic duct.
- Type III: atresia of the right and left hepatic duct.
Pathophysiology
As the biliary tract cannot transport bile to the intestine, bile is retained in the liver (known as stasis) and results in cirrhosis of the liver.
There have been many theories about etiopathogenesis such as Reovirus 3 infection, congenital malformation, congenital CMV infection, autoimmune theory. This means that the etiology and pathogenesis of biliary atresia are largely unknown. However, there have been extensive studies about the pathogenesis and proper management of progressive liver fibrosis, which is arguably one of the most important aspects of biliary atresia patients. As the biliary tract cannot transport bile to the intestine, bile is retained in the liver (known as stasis) and results in cirrhosis of the liver. Proliferation of the small bile ductules occur, and peribiliary fibroblasts become activated. These "reactive" biliary epithelial cells in cholestasis, unlike normal condition, produce and secrete various cytokines such as CCL-2 or MCP-1, Tumor necrosis factor (TNF), Interleukin-6 (IL-6), TGF-beta, Endothelin (ET), and nitric oxide (NO). Among these, TGF-beta is the most important profibrogenic cytokine that can be seen in liver fibrosis in chronic cholestasis. During the chronic activation of biliary epithelium and progressive fibrosis, afflicted patients eventually show signs and symptoms of portal hypertension (esophagogastric varix bleeding, hypersplenism, hepatorenal syndrome(HRS), hepatopulmonary syndrome(HPS)). The latter two syndromes are essentially caused by systemic mediators that maintain the body within the hyperdynamic states.
Associated anomalies include, in about 20% cases,
- Cardiac lesions
- Polysplenia
- Situs inversus
- Absent vena cava
- A preduodenal portal vein
Causes
There is no known cause of biliary atresia.
Epidemiology and Demographics
Biliary atresia is a very rare disorder. About one in 10,000 to 20,000 babies in the U.S are affected every year. Biliary atresia seems to affect girls slightly more often than boys. Within the same family, it is common for only one child in a pair of twins or only one child within the same family to have it. Asians and African-Americans are affected more frequently than Caucasians. There does not appear to be any link to medications or immunizations given immediately before or during pregnancy.
Natural History, Complications and Prognosis
Complications
If unrecognised, the condition leads to liver failure but not (as one might think) to kernicterus. This is because the liver is still able to conjugate bilirubin, and conjugated bilirubin is unable to cross the blood-brain barrier.
Prognosis
Recent large volume studies from Davenport et al. (Ann Surg, 2008) show that age of the patient is not an absolute clinical factor affecting the prognosis. In the latter study, influence of age differs according to the disease etiology—i.e., whether isolated BA, BASM (BA with splenic malformation ), or CBA(cystic biliary atresia).
Diagnosis
Prolonged jaundice that is resistant to phototherapy and/or exchange transfusions should prompt a search for secondary causes.
History
Initially, the symptoms are indistinguishable from neonatal jaundice, a common phenomenon.
Symptoms are usually evident between two and six weeks after birth.
Infants and children with biliary atresia have progressive cholestasis with all the usual concomitant features:
- Jaundice
- Pale stools
- Dark urine
- Pruritus
- Malabsorption with growth retardation
- Eventually cirrhosis with portal hypertension.
- Swollen abdominal region(Ascites) and
- Large hardened liver (which may or may not be observable by the naked eye).
Physical Examination
- Swollen abdominal region(Ascites) and
- Large hardened liver.
Laboratory Findings
- Liver enzymes are generally measured, and these tend to be grossly deranged, hyperbilirubinaemia is conjugated and therefore does not lead to kernicterus.
- Other findings are
- Fat-soluble vitamin deficiencies
- Hyperlipidemia
Other Imaging studies
Ultrasound investigation or other forms of imaging can confirm the diagnosis.
Further testing include radioactive scans of the liver and a liver biopsy.
Treatment
The only effective treatments are certain surgeries, or liver transplantation.
If the intrahepatic biliary tree is unaffected, surgical reconstruction of the extrahepatic biliary tract is possible. This surgery is called a Kasai procedure (after the Japanese surgeon who developed the surgery, Dr. Morio Kasai) or hepatoportoenterostomy.
If the atresia is complete, liver transplantation is the only option. Timely Kasai portoenterostomy (e.g. < 60 postnatal days) has shown better outcomes. Nevertheless, a considerable number of the patients, even if Kasai portoenterostomy has been successful, eventually undergo liver transplantation within a couple of years after Kasai portoenterostomy.
It is widely accepted that corticosteroid treatment after a Kasai operation, with or without choleretics and antibiotics, has a beneficial effect on the postoperative bile flow and can clear the jaundice; but the dosing and duration of the ideal steroid protocol have been controversial ("blast dose" vs. "high dose" vs. "low dose"). Furthermore, it has been observed in many retrospective longitudinal studies that steroid does not prolong survival of the native liver or transplant-free survival. Davenport at al. also showed (hepatology 2007) that short-term low-dose steroid therapy following a Kasai operation has no effect on the mid- and long-term prognosis of biliary atresia patients.
References
Support groups