Obstructive Jaundice - Biliary Atresia PDF

Almustansiriyah University Pediatric Surgery College of Medicine Dr. Muhamed Jassim Department of Surgery MBChB - F.I.C.M.S ────────────────────────────────────────...

Almustansiriyah University Pediatric Surgery College of Medicine Dr. Muhamed Jassim Department of Surgery MBChB - F.I.C.M.S ─────────────────────────────────────────────── Obstructive Jaundice Biliary atresia: Biliary atresia is obliteration of the biliary ducts resulting in an obstructive jaundice. The fibro-obliterative process affects mainly the extrahepatic biliary tree, and to a variable extent the intrahepatic bile ducts. Biliary atresia may be congenital or acquired, and it is the most common surgically treatable cause of jaundice in the first two months of life, that progress to liver cirrhosis and death within the first 2 years if left untreated. The incidence rate is approximately 1/8000 - 1/15000 live births with slight female predominance, and the highest incidence is reported in Ascian population. According to the presence or absence of associated anomalies; biliary atresia is divided into two types: ❖ Isolated biliary atresia (postnatal form): accounting for about 65-90% of cases. ❖ Syndromic biliary atresia (fetal/embryonic form): accounting for about 10-35% of cases, and characterized by the presence of other associated anomalies as interrupted inferior vena cava, preduodenal portal vein, intestinal malrotation, situs inversus, cardiac defects, and polysplenia. Etiology: The exact etiology and pathogenesis of biliary atresia remain poorly understood. However, various etiological mechanisms have been proposed and include: 1  Intrauterine or perinatal viral infection as reovirus, rotavirus, cytomegalovirus, papillomavirus, and Epstein-Barr virus. Immune/inflammatory reaction against bile duct epithelial cells due to abnormal expression of human leukocyte antigens (HLAs), or intracellular adhesion molecules on their surfaces. Genetic factors as defective morphogenesis and differentiation of hepatic diverticulum from the foregut in the early fetal life. Exposure to certain toxins that cause injury to the biliary ducts and subsequently progressive inflammatory process causing their fibrosis and obliteration. Vascular or metabolic insult to the developing biliary tree. Classification: Biliary atresia is classified into three types according to the site of atresia: Type I: atresia of common bile duct. Type II a: atresia of common hepatic duct. Type II b: atresia of common bile duct, common hepatic duct, and cystic duct. Type III: atresia of all extrahepatic bile ducts up to the porta hepatis. This type is the most common form of biliary atresia accounting for more than 90% of cases. Clinical Features: Patients with biliary atresia are typically full terms, and present with features of obstructive cholangiopathy as jaundice, pale (clay-colored) stool, dark colored urine, and hepatomegaly. Meconium staining may be normal, and the stool may be yellow in the early neonatal period in more than half of patients, but with time the stool become pale and the urine turn dark. Malnutrition, anemia, and growth retardation develop in most patient due to fat and fat-soluble vitamins malabsorption. Syndromic biliary atresia is usually presents in the early neonatal period and must be suspected if jaundice persists beyond 2 weeks of life (not physiological jaundice), especially if the hyper- bilirubinemia is of direct type. While isolated biliary atresia is usually presents within 3-4 weeks of life. 2 Investigations: Workup should be considered to exclude biliary atresia from other causes of jaundice, as early operative repair of biliary atresia is associated with better outcomes. ❖ Laboratory tests: ✓ Liver function test: showing elevated levels of alanine transaminase (ALT), aspartate transaminase (AST), and marked increase in alkaline phosphatase (ALP), and Gamma- glutamyl transpeptidase (GGTP). ✓ Serum bilirubin: show hyperbilirubinemia with the direct fraction forming 50%-80% of the total bilirubin level. ✓ Coagulation profile: as prothrombin time (PT), and activated partial thromboplastin time (PTT) to identify the degree of hepatic dysfunction, and as a preoperative preparation. ✓ Virology screen: as Hepatitis A, B, and C serology, and TORCH titers to exclude neonatal hepatitis as a cause of jaundice. ❖ Abdominal ultrasound (U/S): In biliary atresia; the gallbladder is small, shrunken, and noncontractile, and there is increased echogenicity of the enlarged liver. The presence of polysplenia is pathognomonic to biliary atresia. Sometime, a well-defined triangular area of high echogenicity is seen at the porta hepatis, and represents the remnants of the fibrotic biliary tree (Triangular cord sign). Ultrasound is also useful in identifying other causes of obstructive jaundice as choledochal cyst, and inspissated bile syndrome. ❖ Duodenal fluid aspiration: Is easy, rapid test, and done by inserting a specific tube through the nose, or mouth down to the duodenum under radiological guidance. Biliary atresia can be excluded if bile-stained fluid is aspirated from the duodenal lumen. ❖ Hepatobiliary scintigraphy (isotope scan): Done by IV administration of a specific radioactive isotope that is taken up by the hepatocytes, and secreted into the bowel through the bile. In biliary atresia, isotope uptake by hepatocytes is rapid but isotope excretion to the bowel is absent even in delayed films. In contrast, in hepatocellular jaundice the uptake is delayed, and intestinal secretion is present. ❖ Percutaneous cholecystocholangiography: Done by administration of a contrast material into the gallbladder percutaneously under radiological guidance, and is indicated to delineate the anatomy of biliary tree. ❖ Percutaneous liver biopsy: Showing evidence of cholestasis as inflammatory cells infiltration, narrowed, distorted, irregular bile ducts, proliferation of biliary neoductules, parenchymal fibrosis and bile plugging. 3 Treatment: The surgical procedure of choice for biliary atresia is Roux-en-Y hepatic portoenterostomy (Kasai operation), followed by liver transplantation when necessary. The principles of the operation include: ✓ dissection and resection of all extrahepatic biliary tree, including the atretic gallbladder, from the duodenal wall up to the porta hepatis, to expose the small bile ducts/ductules (i.e. tributaries of the right and left hepatic ducts) that are still patent at the porta hepatis. ✓ the jejunum is transected about 10cm distal to duodenojejunal junction, and the distal jejunal limb is anastomosed to the porta hepatis to establish bile flow to the intestine. ✓ bowel continuity is re-established by direct end to side jejunojejunostomy. Hepatic portoenterostomy is not curative for biliary atresia, but buy time until the child achieves normal growth to undergo liver transplantation. The success rate of the procedure is time- dependent, with the best result obtained if the operation is done before 2 months of age. Hepatic portoenterostomy is contraindicated if there is an established liver cirrhosis which usually develops after 3-4 months of life, and in these circumstances liver transplantation should be scheduled from the start. Following hepatic portoenterostomy; approximately one third of patients have inadequate bile flow as indicated by persistent acholic stool, and high bilirubin level (> 6mmol/l). These patients must be scheduled for liver transplantation to avoid life-threating complications of liver cirrhosis. The remaining two thirds of patients will achieve good bile flow, and have good hepatic functions initially. However, more than half of these patients will develop progressive liver impairment in the first few years of life due to progressive obliteration of the intrahepatic biliary ducts causing liver cirrhosis and failure ,and eventually will need liver transplantation. Five years survival rate following liver transplantation is about 90%. 4  Choledochal cyst Choledochal cyst is a congenital dilatation of the biliary tract, which may involve the intrahepatic biliary ducts, the extrahepatic biliary ducts, or both. The incidence rate of choledochal cyst is highly variable around the world, with the highest incidence in Asian countries at a reported rate of 1/1000 live births. While in western countries; the disease is relatively rare with an incidence of one case every 100000-150000 live births. Choledochal cyst is more prevalent in female with female-male ratio of 3.2:1. Etiology: The most commonly accepted theory for the pathogenesis of choledochal cyst is long common biliopancreatic channel. Normally, the common bile duct (CBD) and pancreatic duct unite to form short common biliopancreatic channel within the duodenal wall. This short biliopancreatic channel is well surrounded by the sphincter of Oddi, which prevents reflux of pancreatic fluid into the biliary tree. If the common channel is longer than normal; part of it will not be surrounded by the normal sphincter, allowing reflux of the pancreatic secretions into the biliary tree. The proteolytic pancreatic enzymes are activated and cause epithelial and mural damage to the biliary tree, and subsequently, weakness and dilatation. 5 Classification: Choledochal cyst is classified into five types: ❖ Type I: Dilatation of CBD. This is the most common type accounting for about 90% of cases, and subclassified into: I a: Cystic dilatation of CBD. I b: Fusiform dilatation of CBD. ❖ Type II: Diverticulum of CBD. ❖ Type III: Choledochocele (dilatation of the terminal CBD within the duodenal wall). ❖ Type IV: Dilatation of the extrahepatic bile ducts +/- intrahepatic bile ducts, and subclassified into: IV a: Multiple dilatations of the extrahepatic and intrahepatic bile ducts. IV b: Multiple dilatations of the extrahepatic bile ducts. ❖ Type V: Multiple dilatations of the intrahepatic bile ducts (Caroli disease). Clinical presentations: The clinical manifestations of choledochal cyst vary according to the age of presentation, and the type of the cyst. Choledochal cyst may present early during infancy or remain asymptomatic till adulthood. Infants with choledochal cyst usually present with abdominal mass in the right upper quadrant, and obstructive jaundice (jaundice, acholic stool, and darkened urine). While children usually present with right upper quadrant colicky abdominal pain. The cystic type of choledochal cyst usually presents with abdominal mass, whereas the fusiform type presents with abdominal pain. The classical triad of abdominal pain, abdominal mass, and jaundice is seen in about 2% of cases. Sometimes, choledochal cyst may present with pancreatitis, or cholangitis with abdominal pain, nausea, vomiting, fever, and jaundice. Rarely, choledochal cyst may present with acute abdomen due to cyst rupture and biliary peritonitis. Investigations: ❖ Laboratory tests: as complete blood count (CBC), liver function test (LFT), total serum bilirubin (TSB), and serum amylase. ❖ Radiological investigations: 6  Abdominal Ultrasonography: is the initial imaging of choice to evaluate the position and shape of choledochal cyst, the status of the proximal biliary ducts, vascular anatomy, and hepatic texture. Magnetic resonance cholangiopancreatography (MRCP): is highly accurate in the detection and classification of the cyst with overall detection rate of about 96–100%. Endoscopic retrograde cholangiopancreatography (ERCP): allows excellent definition of the cyst as well as the entire anatomy of the biliary tree including the pancreaticobiliary junction. However, this investigation is invasive and has complications such as pancreatitis, perforation of the duodenal wall or biliary tracts, hemorrhage, and sepsis. Computed tomography (CT) with contrast: is indicated in some patients with pancreatitis. Treatment: ❖ Surgical resection of choledochal cyst is recommended to avoid the consequences and com- plications of the cyst as recurrent cholangitis, recurrent pancreatitis, gallstone formation, biliary cirrhosis, and malignant transformation as cholangiocarcinoma. ❖ The preferred surgical approach for most patients is cyst excision (cystectomy), and bilio- enteric anastomosis. The cyst must be excised from the level of common biliopancreatic channel distally to the common hepatic duct proximally including the gallbladder and cystic duct. The common hepatic duct is then anastomosed to the duodenum (hepatico- duodenostomy), or to the jejunum (Roux-en-Y hepaticojejunostomy) to restore the flow of bile to the intestine. ❖ Previously, choledochal cyst was treated by Cystoduodenostomy or Cystojejunostomy. Both operations associated with high risk of cholangitis, stone formation, and malignant degeneration, and have been abandoned nowadays. 7 ❖ Type II choledochal cyst is treated by excision of the diverticulum, and closure of common bile duct over a T-tube. ❖ Type III choledochal cyst is treated by endoscopic sphincterotomy with or without unroofing of the choledochocele. ❖ Type V choledochal cyst is treated by partial hepatectomy (lobectomy or segmentectomy) for a localized disease, and liver transplantation for a diffuse disease. ❖ External drainage is indicated for a perforated cyst in patients whose condition is too unstable to perform cystectomy and a bilio-enteric anastomosis. ❖ Patients present with biliary infection (as cholangitis) are treated initially with the appropriate antibiotics and supportive measures to control the infection, and the surgical intervention is undertaken thereafter. 8