Gallstones (Cholelithiasis)

Epidemiology:

• Prevalence of ~10%
• ‘Fair, fat, females in their fifties’
• Can occur at any age in any sex
• 2-4x more common in women than in men

There are two main types of stone:

• Pure cholesterol stones (20%)
• Mixed cholesterol and bile pigment, mainly Bilirubin (75%)

Aetiology:

There are three main predisposing factors:

Cholesterol supersaturation: Cholesterol is insoluble in water. In bile, it is normally solubilised in lecithin-bile acid aggregates (micelles). If the conc. in bile is high, the capacity of this mechanism becomes exceeded and nucleation of cholesterol occurs.

Stasis: This may be caused by:

• Fasting
• TPN
• Truncal vagotomy (loss of stimulation to gallbladder emptying)

Increased Bilirubin secretion in bile or deconjugation: Bilirubin is kept in solution by conjugation with glucuronide. Pigment stones form when there is:

• Haemolysis
• Failure of conjugation

Complications:

Gallstones anywhere in the biliary tree can be asymptomatic (silent) and lie undetected for many years. They become clinically evident by the complications they cause:

Gallbladder:

• Biliary colic
• Acute cholecystitis
• Chronic cholecystitis
• Empyema
• Mucocele

Common bile duct:

• Obstructive jaundice
• Cholangitis
• Pancreatitis

Small intestine:

• Gallstone ileus