Parasites and Biliary stones

Choledocholithiasis ٧٠
encountered in the following conditions: Stasis in the biliary tract caused
by strictures, tumours, aberrant sphincter of Oddi motility and sclerosing
cholangitis (Cuschieri, 2002). Hydrolysis of bilirubin by bacterial b-
glucuronidase leads to formation of unconjugated bilirubin which can
precipitate as calcium bilirubinate (Swidsinski et al., 1995).
In Asian populations, infestation with ascaris lumbricoides and
clonorchis sinensis may promote stasis by either blocking the biliary
ducts or by damaging the duct walls, resulting in stricture formation.
Bactibilia is also common in these instances, probably secondary to
episodic portal bacteremia. Some authors have suggested that the stones
are formed because of the bactibilia alone and that the parasites' presence
is just a coincidence (Dandan et al., 2005).
Primary stones are often soft, smooth, yellowish in color, non-
cholesterol in nature, and conform to the shape of the bile duct (Guirgiu
and Roslyn, 1997).
Secondary ductal calculi:
Secondary stones are chemically similar to coexisting stones in the
gallbladder. Predominantly, cholesterol in 80% and black pigment in
20%. They have the typical spectrum of cholesterol and black pigment
stones. Bacteria can be cultured from the surface of cholesterol and
pigment stones but not from the core, suggesting that bacteria do not play
a role in their formation (Dandan et al., 2005).
Clinical manifestation of ductal calculi:
A- Symptoms:
If stones in the biliary tree are small enough, they may pass into the
duodenum. However, the distal duct is only 2 to 3 mm in diameter, so
stones exceeding this size can obstruct biliary outflow, which leads to