The gallbladder is a small sac that holds bile, a digestive juice produced by the liver that is used in the breakdown of dietary fats. The gallbladder extracts water from its store of bile until the liquid becomes highly concentrated. The presence of fatty foods triggers the gallbladder to squeeze its bile concentrate into the small intestine.
Gallstones (biliary calculi) are small stones made from cholesterol, bile pigment and calcium salts, usually in a mixture that forms in the gallbladder. They are a common disorder of the digestive system, and affect around 15 per cent of people aged 50 years and over.
Some things that may cause gallstones to form include the crystallisation of excess cholesterol in bile and the failure of the gallbladder to empty completely.
In most cases, gallstones don’t cause any problems. However, you might need prompt treatment if stones block ducts and cause complications such as infections or inflammation of the pancreas (pancreatitis).
Surgeons may remove your gallbladder (called a cholecystectomy) if gallstones (or other types of gallbladder disease) are causing problems. Techniques include laparoscopic (‘keyhole’) cholecystectomy or open surgery. The gallbladder is not a vital organ, so your body can cope quite well without it.
Symptoms of gallstones
In approximately 70 per cent of cases, gallstones cause no symptoms. The symptoms of gallstones may include:
pain in the abdomen and back. Pain is generally infrequent, but severe
increase in abdominal pain after eating a fatty meal
fever and pain, if the gallbladder or bile duct becomes infected.
Types of gallstones
There are three main types of gallstones being:
mixed stones – the most common type. They are made up of cholesterol and salts. Mixed stones tend to develop in batches
cholesterol stones – made up mainly of cholesterol, a fat-like substance that is crucial to many metabolic processes. Cholesterol stones can grow large enough to block bile ducts
pigment stones – bile is greenish-brown in colour, due to particular pigments. Gallstones made from bile pigment are usually small, but numerous.
Causes and risk factors for gallstones
Gallstones are more common in women than in men. They are also more common in overweight people and people with a family history of gallstones.
There is no single cause of gallstones. In some people, the liver produces too much cholesterol. This can result in the formation of cholesterol crystals in bile that grow into stones. In other people, gallstones form because of changes in other components of bile or because the gallbladder does not empty normally.
Diagnosis of gallstones
Doctors diagnose gallstones by using a number of tests, including:
general tests – such as physical examination and x-rays
ultrasound – soundwaves form a picture that shows the presence of gallstones
endoscope test – endoscopic retrograde cholangiopancreatography (ERCP). A thin tube is passed through the oesophagus and injects dye into the bowel to improve the quality of x-ray pictures
hepatobiliary iminodiacetic acid (HIDA) scan – a special type of nuclear scan that assesses how well the gallbladder functions
magnetic resonance cholangiopancreatography (MRCP) – a form of the body-imaging technique magnetic resonance imaging (MRI). The person’s liver, biliary and pancreatic system is imaged using an MRI unit. The image is similar to an ERCP test.
Complications of gallstones
If gallstones cause no symptoms, you rarely need any treatment.
Complications that may require prompt medical treatment include:
biliary colic – a gallstone can move from the body of the gallbladder into its neck (cystic duct), leading to obstruction. Symptoms include severe pain and fever
inflammation of the gallbladder (cholecystitis) – a gallstone blocks the gallbladder duct, leading to infection and inflammation of the gallbladder. Symptoms include severe abdominal pain, nausea and vomiting
jaundice – if a gallstone blocks a bile duct leading to the bowel, trapped bile enters the person’s bloodstream instead of the digestive system. The bile pigments cause a yellowing of the person’s skin and eyes. Their urine may also turn orange or brown
pancreatitis – inflammation of the pancreas, caused by a blocked bile duct low down near the pancreas. Pancreatic enzymes irritate and burn the pancreas and leak out into the abdominal cavity
cholangitis – inflammation of the bile ducts, which occurs when a bile duct becomes blocked by a gallstone and the bile becomes infected. This causes pain, fever, jaundice and rigors (shaking)
infection of the liver
cancer of the gallbladder (occurs rarely).
Treatment for gallstones
Gallstones that cause no symptoms, generally don’t need any medical treatment. In certain cases (such as abdominal surgery for other conditions), doctors may remove your gallbladder if you are at high risk of complications of gallstones.
Treatment depends on the size and location of the gallstones, but may include:
dietary modifications – such as limiting or eliminating fatty foods and dairy products
lithotripsy – a special machine generates soundwaves to shatter the gallstones. This treatment is used in certain centres only, for the minority of people with small and soft stones
medications – some medications can dissolve gallstones, but this treatment is only rarely given, due to side effects and a variable success rate