Gallstones are crystal-like masses that typically form in the gallbladder. The gallbladder is a small organ located on the right side of the abdomen, just below the liver. The gallbladder's main function is to store bile (made by the liver) and secrete it into the small intestine to help digestion. Bile is made of water, cholesterol, fats, bile salts (natural detergents that break up fat), and a pigment called bilirubin. Gallstones form if the bile contains too much cholesterol, bile salts, or bilirubin.
There are two types of gallstones. Cholesterol stones contain mostly hardened cholesterol and account for approximately 80% of gallstones. Pigment stones are made of bilirubin and account for the other 20%. Gallstones can range in size from very small to as large as a golf ball. The gallbladder may develop any number and size of stones.
Gallstones are more common in women and people who are older, as well as in certain groups of people, such as people of First Nations descent and people who are overweight. In Canada, 20% of women and 10% of men over the age of 60 have gallstones, but many never experience symptoms. However, complications from gallstones can be serious if symptomatic stones are left untreated.
Medical understanding of how gallstones develop is increasing. It's believed that gallstones may be caused by a combination of factors including heredity, obesity, and the ability of the gallbladder to contract (motility).
Cholesterol gallstones form when there's too much cholesterol in the bile and not enough bile salts. Problems with the gallbladder's motility may cause the bile to become too concentrated and lead to stone formation.
The cause of pigment stones is uncertain. They tend to develop in people with pre-existing conditions such as cirrhosis, biliary tract infections, and hereditary blood disorders such as sickle cell anemia.
Risk factors that may lead to the formation of gallstones include:
- gender – women between 20 and 60 years of age are three times as likely to develop gallstones as men
- age – people over the age of 60
- estrogen – women who are pregnant or using hormone replacement therapy (HRT) or birth control pills
- obesity – a large clinical study showed that being even moderately overweight increases the risk for gallstone formation
- ethnicity – some ethnic groups have a higher prevalence of gallstones
- certain cholesterol-lowering medications – these medications lower cholesterol in the blood but lead to an increase in the amount of cholesterol secreted in bile
- diabetes – people with diabetes generally have high levels of fatty acids called triglycerides which increase the risk of gallstones
- rapid weight loss – this causes the liver to secrete extra cholesterol into the bile
- fasting – this inhibits the gallbladder's ability to contract, causing high concentrations of cholesterol to build up in the bile
- a diet high in fat and sugar along with an inactive lifestyle – this sets the stage for increased risk for gallstones
Symptoms and Complications
Most people with gallstones don't have symptoms. Gallstones in these cases are known as silent stones. They're sometimes detected during tests for an unrelated condition and usually don't need to be treated.
Problems arise when a gallstone attack occurs. Attacks may occur over a period of weeks, months or even years. However, once a full attack occurs, subsequent attacks are more likely. One attack may last from 20 minutes to several hours. Symptoms of an attack include:
- persistent, severe pain in the upper middle or upper right abdomen that increases rapidly
- pain in the back between the shoulder blades
- pain under the right shoulder
- nausea and vomiting
Other signs and symptoms of gallstones may be vague and non-specific.
The gallbladder is attached to the liver and small intestine by a series of tubes called ducts. Complications can occur if gallstones block the flow of bile by lodging in any of the ducts that carry the bile from the liver and gallbladder to the small intestine. Trapped gallstones may lead to gallbladder inflammation (cholecystitis) and duct inflammation (cholangitis). Gallstones may also become trapped in the pancreatic duct, which can cause painful inflammation (pancreatitis).
Beware of symptoms such as jaundice (yellowing of the skin and whites of the eyes), fever, clay-coloured stools, tea- or coffee-coloured urine, and persistent pain.
Making the Diagnosis
When symptoms seem to indicate a gallstone, your doctor may suggest an ultrasound of the abdomen. A technician will pass a handheld device that emits sound waves over the abdomen. Sound waves bounce off organs and other solid masses, revealing the presence of gallstones.
In addition, blood test results may show a pattern of abnormal liver enzymes that suggests bile ducts may be obstructed by gallstones. Several other tests can provide additional information needed to make a firm diagnosis. These include a computed tomography (CT) scan and various X-ray techniques using a contrast substance or dye to outline the bile ducts. Both ultrasound and CT scanning techniques help detect an obstruction and, if there is one present, doctors can see if it is due to a gallstone or not. Current ultrasound technology allows very small gallstones to be detected.
Treatment and Prevention
Some of the risk factors for gallstone formation can be modified, such as obesity. By maintaining a healthy weight through proper diet and exercise, a person can reduce the chances for gallstones. People with diabetes tend to have a higher risk for gallstones, so keeping weight under control may prevent gallstones from developing. A low-carbohydrate diet and regular physical activity may help prevent gallstones. Also, one should avoid diets that result in losing weight very quickly as risk of developing gallstones will increase.
Most people who have "silent" gallstones in the gallbladder don't require treatment. People with intermittent pain can try avoiding or reducing their intake of fatty foods.
If someone has gallstones in the gallbladder that cause repeated attacks of pain, the doctor may recommend removing the gallbladder. This type of surgery is called a cholecystectomy.
People who have gallstones may develop problems when the gallbladder becomes inflamed. This is called acute cholecystitis. In these cases, sufferers are hospitalized so they can receive fluids intravenously, and antibiotics are usually given as soon as the problem is suspected. If the diagnosis is certain and surgery is not considered risky, the gallbladder is usually removed during the first day or two of the illness.
Today, almost 90% of cholecystectomies in Canada are performed using laparascopic surgery under general anaesthesia. The surgeon makes small incisions in the abdomen and inserts surgical instruments as well as a video camera that projects a magnified view of a patient's internal organs onto a monitor. The gallbladder is removed through one of the incisions. Most people are able to go home after the surgery, but some people may require an overnight stay for additional monitoring.
Open cholecystectomies may be performed if complications are discovered, such as infection or scarring from previous operations. A surgeon may start using laparascopic techniques then switch to open surgery if such a complication is found. In very obese individuals, an open cholecystectomy may be easier to perform.
A person can live normally without a gallbladder. Once removed, bile flows from the liver through the ducts and directly into the small intestine. No change in diet is necessary, although the more frequent flow of bile to the small intestine may lead to diarrhea.
For people who are not able to have surgery, a medication called ursodeoxycholic acid can be used to help dissolve the gallstones. This medication takes about 6 months to work and is effective in only about 50% of people who use it. Gallstones usually come back once a person stops taking the medication.
Shockwaves can be used to break up gallstones in a procedure called lithotripsy. However, surgery is still preferred as gallstones are likely to return if the gallbladder is not removed.