Biliary System

Question 1

What does bile contain?

Answer 1

Bile pigments (from Hb breakdown products)
Cholesterol
Other lipids

Question 2

What is the epidemiology of cholelithiasis?

Answer 2

More common in women
Increases with age
More common in Scandinavia, and Native North and South American Populations

Question 3

What is Cholelithiasis?

Answer 3

Gallstones - refers to the formation of hard stones in the gallbladder

Question 4

How are gallstones classified/?

Answer 4

Stones generally classified as cholesterol stones or pigment stones - in reality they are usually mixed.

Question 5

What is the aetiology of cholelithiasis?

Answer 5

Weight - obesity and sudden weight loss
Family history 
Oestrogen - female gender + oral contraceptive pill
Diet (high fat, low fibre)
Increasing age
Diabetes

‘Fair, fat, female, forty’ used to be a term used to describe the typical patient with gallstones – but as noted above, that is only a selection of the risk factors.

Question 6

What are the three factors needed for the formations of cholesterol gallstones?

Answer 6

High concentration of cholesterol in the gallbladder

Gallbladder stasis

Products that promote the crystallisation of cholesterol – some lipoproteins found in bile do this.

Question 7

How do cholesterol stones form?

Answer 7

Cholesterol stones form when the concentration of micelles is not great enough to hold all the cholesterol in the micelles.

Cholesterol crystals form in bile that is supersaturated with cholesterol resulting in the production of ‘sludge’.

Sludge can then go on to form stones, or it can be reasbsorbed

Sludge can then go on to form stones, or it can be reabsorbed.

Question 8

What drugs increase the risk of cholesterol stones forming?

Answer 8

Clofibrate – A fibrate drug, this lowers plasma cholesterol by increasing cholesterol secretion in bile.

Oral Contraceptive Pill

Question 9

What conditions exacerbate cholesterol stones forming?

Answer 9

Pregnancy

Reduce bile production/circulation e.g.
Crohn’s disease
- Malabsorption where so much bile is lost it cannot be replaced quickly enough

Question 10

What are pigment stones caused by?

Answer 10

Bilirubin Breakdown

Question 11

What are the three main causes that lead to pigment stones?

Answer 11

An increase in bilirubin load, as a result of haemolytic anaemia.

Pigments become less water soluble once in the bile as a result of the action of glucuronidases.
- Thought that most cases of pigment stones result from the subclinical bacterial colonisation of the gallbladder

Cirrhosis – with this there will be depletion of glucuronidase inhibitors in the bile.