Tag: Biliary atresia

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Biliary Atresia

DEfinition:
Biliary atresia is a rare condition in newborn infants in which the common bile duct(that carry a liquid called bile from the liver to the gallbladder) between the liver and the small intestine is blocked or absent. If unrecognized, the condition leads to liver failure — but not kernicterus, as the liver is still able to conjugate bilirubin, and conjugated bilirubin is unable to cross the blood-brain barrier. The cause of the condition is unknown. The only effective treatments are certain surgeries such as the kasai procedure, or liver transplantation.

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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.

This is now effective surgery which can relieve symptoms in most cases. Liver transplant is also an option, and as a result, survival rates are now above 90 per cent.

Causes & b Risk Factors:
Biliary atresia is due to a progressive fibrosis or scarring of the bile ducts responsible for draining bile from the liver, which eventually leads to atresia or loss of the biliary system. It’s not clear how or why this occurs, and many factors may be involved. It may be due to a problem in the developing embryo (10 to 20 per cent – other congenital abnormalities may also be present) or around the time of birth or shortly afterwards (80 to 90 per cent). It occurs more often in Asian and African-American newborns than Caucasian.

Bile is made by the liver and helps with the digestion of fats. If bile is not removed from the liver, it builds up and begins to damage it. The baby will then develop jaundice, or a yellow colour of the skin as levels of the bile chemical bilirubin rise in the blood. Other symptoms include dark coloured urine and pale stools. Many newborn babies become jaundiced but this is usually temporary. Jaundice lasting for longer than 14 days, especially if there are other symptoms such as an enlarged liver or failure to thrive, is a worrying sign and must be investigated further.

Pathophysiology:
There is no known cause of biliary atresia. There have been many theories about ethiopathogenesis 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. 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. Associated anomalies include, in about 20% cases, cardiac lesions, polysplenia, situs inversus, absent vena cava and a preduodenal portal vein.

Symptoms:
Newborns with this condition may appear normal at birth. However, jaundice (a yellow color to the skin and mucous membranes) develops by the second or third week of life. The infant may gain weight normally for the first month, but then will lose weight and become irritable, and have worsening jaundice.

Other symptoms may include:

•Dark urine
•Enlarged spleen
•Floating stools
•Foul-smelling stools
•Pale or clay-colored stools
•Slow growth
•Slow or no weight gain

Diagnosis:
The health care provider will perform a physical exam, which includes feeling the patient’s belly area. The doctor may feel an enlarged liver.

Tests to diagnose biliary atresia include:

•Abdominal x-ray
•Abdominal ultrasound to examine the liver and bile ducts
•A blood test to look for raised levels of bilirubin and check liver enzyme levels and blood clotting
•Hepatobiliary iminodiacetic acid (HIDA) scan, also called cholescintigraphy, to help determine whether the bile ducts and gallbladder are working properly
•Liver biopsy to determine the severity of cirrhosis or to rule out other causes of jaundice
•An abdominal x-ray to look for an enlarged liver and spleen
•X-ray of the bile ducts (cholangiogram)
•An scan to determine how well bile is flowing (HIDA or TEBIDA)

Treatment :
TreatmentIf 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.

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If the atresia is complete, liver transplantation is the only option(currently has a greater than 95 per cent survival rate at one year). 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.

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).

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.

Prognosis:
Early surgery will improve the survival of more than a third of babies with this condition. The long-term benefit of liver transplant is not yet known, but is expected to improve survival.

Possible Complications:
•Infection
•Irreversible cirrhosis
•Liver failure
•Surgical complications, including failure of the Kasai procedure

Prevention:
The earlier biliary atresia is detected, the less damage it will have done to the liver and the better the chance of a successful outcome to treatment. The current target is to treat babies before they are eight weeks old.

If the liver has not yet been damaged by cirrhosis, the condition is usually treated through an operation called a Kasai portoenterostomy (or a similar procedure). This involves using a loop of bowel to form a duct to drain the bile from the liver. The operation is named after the Japanese surgeon, Professor Morio Kasai, who developed it in 1959. It was first introduced in the UK in the 1960s.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://www.bbc.co.uk/health/physical_health/conditions/biliary_atresia.shtml
http://www.nlm.nih.gov/medlineplus/ency/article/001145.htm
http://en.wikipedia.org/wiki/Biliary_atresia

http://www.mikylah.com/pictures.html

http://www.chw.health.nsw.gov.au/parents/factsheets/biliary_atresia.htm

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