The gallbladder is a pear-shaped sac that hangs like a little pod from a tree branch. This pod and its branch – the cystic duct – are attached to the common hepatic duct, which comes from the liver. These ducts lead into the common bile duct, which is attached to the duodenum, the entry to the small intestine. All the ducts from the liver and gallbladder itself form the biliary system, often called the biliary tree for obvious reasons.

The liver produces bile, a yellow-green-brownish liquid that helps digest fats and rid the body of certain waste products. Bile is made of water, lecithin, cholesterol, bile salts, and bilirubin. It is carried through bile ducts from the liver into the gallbladder, where it is stored and concentrated. When you eat fat-containing foods your gallbladder contracts and ejects the bile back through the ducts and into the small intestine, where it helps digest the fat.

If the liquid bile contains the wrong proportion of cholesterol, bile salts, or bilirubin, under certain conditions it can harden into stones that can block or interfere with the normal flow of bile. The result can be a sharp pain or a painful spasm on the right side, or in the midline of the upper abdomen just under the rib cage. Sometimes you can feel the pain radiate to your back under the right shoulder blade. Symptoms often flare after meals (especially high-fat meals) because the gallbladder normally contracts after you eat fatty, greasy, or oily foods.

When a stone blocks the outflow of bile, the gallbladder becomes inflamed, a condition called cholecystitis. Gallbladder inflammation without stones present, called acalculous cholecystitis, may be brought on by prolonged fasting, severe illness, or for no obvious reason. Cancer can develop in the gallbladder and the biliary ducts, but this is rare.

The most common condition affecting the gallbladder is gallstones.

Types of Gallstones

Most of the 25-30 million Americans who have gallstones never notice them. Even if the stones are discovered by a doctor, in most cases there is no need to treat them unless they begin to cause discomfort and pain.

There are two main types of gallstones: cholesterol stones and pigmented stones. In America, most people have the cholesterol gallstones; in Asia, gallstones are more often pigmented. Gallstones can be as small as a grain of sand or as large as a golf ball. The gallbladder can develop just one large stone, hundreds of tiny stones, or almost any combination. It is believed that the mere presence of gallstones may cause more gallstones to develop. Small gallstones may exhibit mobility, while large stones often sit tight.

Cholesterol stones

These are usually yellow-green and are made primarily of fat and cholesterol. Scientists believe that cholesterol stones form when bile contains too much cholesterol, too much bilirubin, or not enough bile salts (a fat-dissolving detergent) or when the gallbladder does not empty as it should for some other reason. More than 75% of these stones are found in people living in developed countries. Larger stones are associated with cholecystitis. Smaller ones can travel down the digestive system to where the ducts join the pancreas. These are associated with pancreatitis.

Pigment stones

These are small, black or brown stones made of bile pigment – bilirubin – combined with calcium. They tend to develop in people who have cirrhosis of the liver, biliary tract infections, or hereditary blood disorders such as sickle-cell anaemia – in which too much bilirubin forms. Old red blood cells when removed from the bloodstream by the spleen release the red-pigmented haemoglobin. Haemoglobin is converted to the yellow-pigmented bilirubin, which is then excreted by the liver and released in to the bile. If the body destroys too many red cells (a condition called hemolysis) excess bilirubin is produced and thus pigment stones can form in the gallbladder. Sickle-cell anaemia causes early destruction of red cells, and many people with this condition have a gallbladder condition by the age of 20.

Calcification of stones

This frequently occurs, resulting in them becoming hardened. About 15% of stones contain so much calcium that they can be seen on plain x-rays as calcified, or hardened. Calcification of cholesterol stones typically occurs only at the rim. Calcified gallstones may be resistant to efforts to dissolve them.

Biliary sludge

This is thickened gallbladder mucoprotein with tiny cholesterol crystals that may be a precursor of gallstones. Typically this sludge pauses biliary pain, cholecystitis (acalculous) or acute pancreatitis. It is often found during pregnancy, during prolonged intravenous feeding, rapid weight loss, or starvation.

The risk of getting gallstones

If you are overweight, middle-aged woman or a Native American man or woman, you are at the highest risk of having gallstones. Twice as many women as men get gallstones, and all people over the age of 60 are more likely to develop gallstones than younger people. Up to 10% of all adults in Western countries have gallstones. The following factors can predispose you to having stones in the gallbladder.

Obesity

This is a major risk factor, especially in women. A number of clinical studies have shown that being even moderately overweight increases your risk for developing gallstones. The risk is especially high in people with the highest body mass index. Obesity tends to reduce the amount of bile salts in bile, resulting in more cholesterol, and it also decreases gallbladder emptying.

Rapid weight loss

As the body metabolises fat during rapid weight loss, it causes the liver to secrete extra cholesterol into bile, which can cause gallstones. There is some controversy over whether conventional dieting to lose weight causes gallstones.

Fasting

Prolonged starvation decreases gallbladder movement, causing the bile to become over concentrated with cholesterol, which can lead to gallstones. People who are receiving long-term intravenous feeding face this risk.

Elevated estrogen production

Pregnancy, hormone replacement therapy, or birth control pills appear to increase cholesterol levels in bile and decrease gallbladder movement, both of which can lead to gallstones. Estrogen increases bile acid production, thus decreasing the solubilization of cholesterol.

Ethnicity

Native Americans have a genetic predisposition to secrete high levels of cholesterol bile. In fact, they have the highest rate of gallstones in the US. Among the Pima Indians of Arizona, 70% of women have gallstones by the age of 30. A majority of Native American men develop gallstones by the age of 60. Mexican American men and women of all ages also have higher rates of gallstones. Some studies have indicated that Scandinavian women maybe at a slightly higher risk than other women.

Cholesterol lowering drugs

Drugs that lower cholesterol levels in the blood actually increase the amount of cholesterol secreted in the bile. This in turn can increase the risk of gallstones.

Low caffeine intake

Apparently coffee – with caffeine – stimulates gallbladder contraction and thus lowers the risk of gallstones in women.

Sedentary lifestyle

This put you in a 30 to 40% increased risk compared to people who engage in recreational physical activity.

High triglyceride levels

Your total cholesterol level is not a risk factor for gallstones, but elevated fatty acids called triglycerides are clearly linked to gallstone formation. A low level of HDL cholesterol may be associated with gallstone disease. HDL is the good cholesterol, as opposed to LDL, which is unhealthy. People with diabetes generally have high levels of triglycerides.

High red blood cell turnover

People with anaemia, sickle-cell disease, thalassaemia, hereditary spherocytosis, elliptocytosis, or liver dysfunction (jaundice) are at higher risk.

Symptoms of gallstones

Gallstones don’t always cause problems. “Silent stones” are sometimes discovered during diagnostic tests for other problems but don’t interfere with gallbladder, liver, or pancreas functions. Some people feel pain after eating fatty foods but have no other symptoms. When gallbladder symptoms occur, they may do so suddenly, and for that reason are often called a gallstone attack. Typical symptoms of gallstones include:

Non-specific abdominal pain

Steady pain to the right upper abdomen that increases rapidly and lasts from 30 minutes to several hours

Pain in the back between the shoulder blades or under the right shoulder

Nausea and vomiting

Abdominal bloating, belching, and gas

Recurring intolerance of fatty foods

Colic

Indigestion

When severe, symptoms are similar to those heart attack, reflux disease, appendicitis, ulcers, irritable bowel syndrome, hiatal hernia, pancreatitis, and hepatitis. Accurate diagnosis is critical.

More urgent symptoms

Gallstones can become a more serious problem if they acutely block bile ducts. If you have any of the following, see a doctor immediately because your condition could be more serious, such as gallbladder infection or itching (pruritus), a frequent complication of cholestatis, the stoppage of bile flow. Symptoms of pancreatitis also could cause severe knife-like pain in the back.

Sweating

Chills

Low-grade fever

Yellowish colour of the skin or whites of the eyes

Clay-coloured stools