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
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.
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,
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.