CONGENITAL ABNORMALITIES OF THE GALL BLADDER AND BILE DUCTS Embryology

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, recanalisa- tion subsequently occurs and bile begins to flow. During early fetal 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 is present in 2–6% of cholecy- stograms and may be mistaken for a pathological deformity of the organ. ‘Phrygian cap’ refers to hats worn by the people of Phrygia, an ancient country of Asia Minor; it was rather like a liberté 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 duplicated. One 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.