Congenital abnormalities of the gall bladder and bile ducts

Embryology

The hepatic diverticulum arises from the ventral wall of the foregut and elongates into a stalk to form the choledochus. A lateral bud is given off which is destined to become the gall bladder and cystic duct. The embryonic hepatic duct sends out many branches which join up the canaliculi between the liver cells. As is usual with embryonic tubular structures, hyper­plasia obliterates the lumina of this ductal system; normally recanalisation subsequently occurs and bile begins to flow. During early foetal life the gall bladder is entirely intrahepatic.

Absence of the gall bladder

Occasionally the gall bladder is absent. Failure to visualise the gall bladder is not necessarily a pathological problem.

The Phrygian cap

The Phrygian cap (Fig. 54.26) is present in 2—6 per cent of cholecystograms and may be mistaken for a pathological deformity of the organ. ‘Phrygian cap’ refers to hats worn by people of Phrygia, an ancient country of Asia Minor; it was rather like a liberte' cap of the French Revolution.

Floating gall bladder

The organ may hang on a mesentery which makes it liable to undergo torsion.

Double gall bladder

Rarely, the gall bladder is twinned. One of the twins may be intrahepatic.

Absence of the cystic duct

This is usually a pathological, as opposed to an anatomical anomaly and indicates the recent passage of a stone or the presence of a stone at the lower end of the cystic duct which is ulcerating into the common bile duct. The main danger at surgery is damage to the bile duct, and particular care to identify the correct anatomy is essential before division of any duct.

Low insertion of the cystic duct

The cystic duct opens into the common bile duct near the ampulla. All variations of this anomaly can occur. At operation they are not important. Dissection of a cystic duct which is inserted low in the bile duct should be avoided as removal will damage the blood supply to the common bile duct and can lead to stricture formation.

An accessory cholecystohepatic duct

Ducts passing directly into the gall bladder from the liver do occur and are probably not uncommon. Nevertheless, larger ducts should be closed but before doing so the precise anatomy should be carefully ascertained (Fig. 54.27).

Extrahepatic biliary atresia

A etiology and pathology

Atresia is present in one per 14 000 live births, and affects male and females equally. The extrahepatic bile ducts are progressively destroyed by an inflammatory process which starts around the time of birth. Intrahepatic changes also occur and eventually result in biliary cirrhosis and portal hypertension. The untreated child dies before the age of 3 years of liver failure or haemorrhage.

The inflammatory destruction of the bile ducts has been classified into three main types (Fig. 54.28):

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 ducts.

  Associated anomalies include, in about 20 per cent of cases, cardiac lesions, polysplenia, situs inversus, absent vena cava and a pre duodenal portal vein.

Clinical features

About one-third of cases are jaundiced at birth. In all, how­ever, jaundice is present by the end of the first week and deep­ens progressively. The meconium may be a little bile stained but later the stools are pale and the urine is dark. Prolonged steatorrhoea gives rise to osteomalacia (biliary rickets). Pruritis is severe. Clubbing and skin xanthomas, probably related to a raised serum cholesterol, may be present.

Differential diagnosis

This includes any form of jaundice in a neonate giving a cholestatic picture. Examples are alpha1-antitrypsin deficiency, cholestasis associated with intravenous feeding, choledochal cyst and inspissated bile syndrome. Neonatal hepatitis is the most difficult to differentiate. Both extrahepatic biliary atre­sia and neonatal hepatitis are associated with giant cell transformation of the hepatocytes. Liver biopsy and radio­nuclide excretion scans are essential.

Treatment

Patent segments of proximal bile duct are found in 10 per cent of type I lesions. A direct Roux-en-Y anastomosis will achieve bile flow in 75 per cent, but progressive fibrosis results in disappointing long-term results. Type II and III are treated by the Kasai procedure, in which radical excision of all bile-duct tissue up to the liver capsule is performed. A Roux-en-Y loop of jejunum is anastomosed to the exposed area of liver capsule above the bifurcation of the portal vein. The chances of achieving effective bile drainage after porto­enterostomy are maximal when the operation is performed before the age of 8 weeks, and approximately 90 per cent of children whose bilirubin falls to within the normal range can be expected to survive for 10 years or more. Early referral for surgery is critical.

Postoperative complications include bacterial cholangitis, which occurs in 40 per cent. Repeated attacks lead to hepatic fibrosis and 50 per cent of long-term survivors develop portal hypertension, with one-third having variceal bleeding. Liver transplantation may be considered in the failures.

Congenital dilatation of the intrahepatic ducts (Caroli’s disease)

This rare, congenital, nonfamilial condition is characterised by multiple irregular sacular dilatations of the intrahepatic ducts separated by segments of normal or stenotic ducts. Biliary stasis leads to stone formation and cholangitis. The patients present in childhood or in early adult life. Associated conditions include congenital hepatic fibrosis, medullary sponge kidney and, rarely, cholangiocarcinoma. The main­stays of treatment are antibiotics for the cholangitis and the removal of calculi. As the condition can be limited to one lobe of the liver, lobectomy may be indicated.

Choledochal cyst

Choledochal cyst is due to a specific weakness in a part of or the whole of the wall of the common bile duct. Anomalous junctions of the biliary pancreatic junction are frequently observed and long common channels result in high levels of biliary amylase in 80 per cent of cases. Common pancreato­biliary channels may be associated with repeated attacks of pancreatitis (Fig. 54.29).  The patient may present at any age with attacks of jaundice of obstructive type, cholangitis and abdominal signs. In some patients a swelling may be detected in the upper abdomen. Ultrasonography will confirm the presence of an abnormal cyst and a magnetic resonance imaging (MRI) scan will reveal the anatomy; in particular, the relationship between the lower end of the bile duct and the pancreatic duct. It appears that the anomaly is premalignant; carcinoma of the biliary tract is a well-recognised complication and carries a poor prognosis, and therefore excision is the appropriate management.

Radical excision of the cyst is the treatment of choice with reconstruction of the biliary tract using a Roux-en-Y loop of jejunum. Other procedures have been shown to be ineffective and associated with recurrent attacks of cholangitis.

Trauma

Injuries to the gall bladder and extrahepatic biliary tree are rare. They occur as a result of a penetrating wound or a crush injury. Operative trauma is perhaps more frequent than external trauma. The physical signs are those of an acute abdomen. The treatment is cholecystectomy for gall bladder injuries and if the bile duct is damaged then drainage using a T-tube to the bile duct and a drain to the site of damage is appropriate. Many will stricture and these can be secondarily be repaired by a Roux-en-Y anastomosis.

Torsion of the gall bladder

This is very rare and relies on a long mesentery which often occurs in an older patient with a large mucocele of the gall bladder. The patient presents with extreme pain and an acute abdomen. Immediate exploration is indicated with cholecystectomy as the only treatment.