Gallstones explained

What are gallstones?

Gall is an old-fashioned word for what we now call bile. Usually bile is a liquid but gallstones are small solid lumps that can form in bile and can give rise to a variety of symptoms. Bile is made in the liver but the body stores it in a small bag just under the liver called the gall bladder. When we eat, the gall bladder empties the bile along a tube (called the bile duct) that leads to the intestines. Once there, the bile mixes with the food that we have eaten to help with digestion.

Why do gallstones form?

Gallstones start as tiny crystals, then grow to resemble gravel, and may end up looking like pebbles. Sometimes, there is just a single stone; often there are several and it is not unknown for the gallbladder to contain literally dozens of small stones. Bile is a mixture of different chemicals. When the bile can no longer hold these chemicals in a liquid solution, gallstones start to form. Gallstones most frequently contain cholesterol. You may have heard of
cholesterol as a fatty substance in our diet that can cause disease in arteries. Cholesterol may be bad for arteries but the liver finds it very useful. Bile contains lots of cholesterol and indeed it is an important way for the body to clear itself of any excess. Bile may contain so much cholesterol that when it is stored in the gall bladder the cholesterol may separate out as little crystals, which may lump together to form a gallstone. 

Your body

Who gets gallstones?

Gallstones are very common, but most people who have them do not know. By the age of 60 nearly a quarter of women (and a rather smaller number of men) will have developed some gallstones. The old saying that gallstones are seen in people with all the ‘Fs’ (fair, fat, female, fertile and forty) has some truth in it, since gallstones are commoner in women, especially those who have had children and who are overweight. However the age at which gallstones may give symptoms has changed a lot in recent years, and doctors see gallstones in much younger women, sometimes even teenagers, although it is certainly true to say they become commoner as we get older. They do seem to be getting rather more common generally, possibly as a result in changes in our diet over the last two generations.

Do they always cause symptoms?

Although gallstones may give rise to a number of different symptoms, they can be found quite incidentally in, for example, somebody who is having x-rays or ultrasound scans done for a completely different reason. Indeed doctors think that most people who get gallstones at some stage during their life are never aware that they have them. In that situation, such stones are best left alone unless they go on to cause symptoms. This only happens in a minority of patients.

What symptoms may gallstones cause?

It is not always clear why gallstones should cause problems for one individual yet leave another quite unaware of their presence. Gallstones usually only give rise to symptoms if they move from the gall bladder into one of the tubes (known as bile ducts) that lead from the gall bladder and the intestine. If they get stuck in the narrow neck of the gall bladder this can cause pain which can be quite severe. This type of pain is called biliary colic. Alternatively, the stones may cause inflammation in the wall of the gall bladder (known as cholecystitis).

If a stone gets into the main duct leading from the liver into the intestine it can give rise not only to pain from biliary colic but it may block the flow of bile from the liver altogether which causes jaundice. By far the commonest symptom caused by gallstones is biliary colic.