The gallbladder is a small pear-shaped organ located beneath the liver on the right side of the abdomen. The gallbladder's primary functions are to store and concentrate bile, and secrete bile into the small intestine to help digest food.
The gallbladder is connected to the liver and the small intestine by a series of ducts, or tube-shaped structures, that carry bile. Collectively, the gallbladder and these ducts are called the biliary system.
Bile is a yellow-brown fluid produced by the liver. In addition to water, bile contains cholesterol, fat, bile salts (natural detergents that break up fat) and bilirubin (the pigment that gives bile and stools their color). The liver can produce as much as three cups of bile in one day, and at any one time, the gallbladder can store up to a cup of concentrated bile.
As food passes from the stomach into the small intestine, the gallbladder contracts and sends its stored bile into the small intestine through the common bile duct. Once in the small intestine, bile helps digest fats in foods. Normally, most bile is recycled in the digestive tract by being absorbed by the intestine and returned to the liver via the bloodstream.
What are gallstones?
Gallstones are pieces of solid material that develop in the gallbladder when substances in the bile, primarily cholesterol and bile pigments, form hard, crystal-like particles. There are two primary types of gallstones:
- Cholesterol stones are usually white or yellow and account for about 80 percent of gallstones. They are made primarily of cholesterol.
- Pigment stones are small, dark stones made of bilirubin and calcium salts that are found in bile. They account for the other 20 percent of gallstones.
Gallstones vary in size and may be as small as a grain of sand or as large as a golf ball. The gallbladder may develop a single, often large, stone or many smaller ones, even several thousand.
What causes gallstones?
Researchers believe that gallstones may be caused by a combination of factors, including inherited body chemistry, body weight, gallbladder motility (movement) and perhaps diet.
Scientists believe cholesterol stones form when bile contains too much cholesterol, too much bilirubin, not enough bile salts, or when the gallbladder does not empty as it should. The cause of pigment stones is uncertain. They tend to develop in people who have biliary tract infections and hereditary blood disorders such as sickle-cell anemia.
It is believed that once one gallstone forms, more gallstones are likely to develop. However, other factors that may contribute to a higher risk of gallstones have been identified and are listed below.
Obesity is a major risk factor for gallstones, especially in women. A large clinical study showed that being even moderately overweight increases the risk for developing gallstones. The most likely reason is that obesity tends to reduce the amount of bile salts in bile resulting in more cholesterol. Obesity also reduces gallbladder emptying.
Excess estrogen from pregnancy, hormone replacement therapy, or birth control pills appears to increase cholesterol levels in bile and decrease gallbladder movement, both of which can lead to gallstones.
Native Americans have a genetic predisposition to secrete high levels of cholesterol in bile. In fact, they have the highest rates of gallstones in the United States. The majority of Native American men have gallstones by age 60; among the Pima Indians of Arizona, 70 percent of women have gallstones by age 30. Mexican-American men and women of all ages also have high rates of gallstones.
Women between ages 20 and 60 are twice as likely to develop gallstones as men in the same age group.
People over age 60 are more likely to develop gallstones than those under age 60.
Drugs that lower cholesterol levels in the blood actually increase the amount of cholesterol secreted in bile. This in turn can increase the risk of cholesterol gallstones.
People with diabetes generally have high blood levels of fatty acids called triglycerides. These fatty acids increase the risk of gallstones.
Rapid weight loss
As the body metabolizes fat during rapid weight loss, it causes the liver to secrete extra cholesterol into the bile, which can cause gallstones.
Fasting decreases gallbladder movement causing the bile to become overconcentrated with cholesterol, which can lead to gallstones.
No clear relationship has been proved between diet and gallstone formation. However, low-fiber, high-cholesterol diets, and diets high in starchy foods may also contribute to gallstone formation.
Who is at highest risk for gallstones?
- People over age 60
- Native Americans
- Overweight men and women
- People who fast or lose a lot of weight quickly
- Pregnant women, women taking hormone therapy and women who use birth control pills
What are the symptoms of gallstones?
Most people with gallstones do not have symptoms. They have what are called silent stones. Studies show that most people with silent stones remain symptom-free for years and require no treatment. Silent stones usually are detected during a routine medical checkup or examination for another illness.
A gallstone attack usually is marked by a steady, severe pain in the upper abdomen. Attacks may last only 20 or 30 minutes but more often they last for one to several hours. A gallstone attack may also cause pain in the back between the shoulder blades or in the right shoulder and may cause nausea or vomiting. Attacks may be separated by weeks, months or even years. Once a true attack occurs, subsequent attacks are much more likely.
Sometimes gallstones may make their way out of the gallbladder and into the cystic duct, the channel through which bile travels from the gallbladder to the small intestine. If stones become lodged in the cystic duct and block the flow of bile, they can cause cholecystitis, an inflammation of the gallbladder. Blockage of the cystic duct is a common complication caused by gallstones.
A less common, but more serious, problem occurs if the gallstones become lodged in the bile ducts between the liver and the intestine. This condition can block bile flow from the gallbladder and liver, causing pain and jaundice. Gallstones may also interfere with the flow of digestive fluids secreted from the pancreas into the small intestine, leading to pancreatitis, an inflammation of the pancreas.
Prolonged blockage of any of these ducts can cause severe damage to the gallbladder, liver, or pancreas, which can be fatal. Warning signs of serious problems include
How are gallstones diagnosed?
Many times gallstones are detected during an abdominal X-ray, computerized axial tomography (CAT) scan or abdominal ultrasound that has been taken for an unrelated problem or complaint.
When actually looking for gallstones, the most common diagnostic tool is ultrasound. An ultrasound examination, also known as ultrasonography, uses sound waves. Pulses of sound waves are sent into the abdomen to create an image of the gallbladder. If stones are present, the sound waves will bounce off the stones, revealing their location.
Ultrasound has several advantages. It is a noninvasive technique, which means nothing is injected into or penetrates the body. Ultrasound is painless, has no known side effects, and does not involve radiation.
How are gallstones treated?
Despite the development of nonsurgical techniques, gallbladder surgery, or cholecystectomy, is the most common method for treating gallstones. Each year more than 500,000 Americans have gallbladder surgery.
Surgery options include the standard procedure, called open cholecystectomy, and a less invasive procedure, called laparoscopic cholecystectomy. The standard cholecystectomy is a major abdominal surgery in which the surgeon removes the gallbladder through a 5- to 8-inch incision. Patients may remain in the hospital about a week and may require several additional weeks to recover at home. Laparoscopic cholecystectomy is a new alternative procedure for gallbladder removal. About 15,000 surgeons have received training in the technique since its introduction in the United States in 1988. Currently about 80 percent of cholecystectomies are performed using laparoscopes.
Laparoscopic cholecystectomy requires several small incisions in the abdomen to allow the insertion of surgical instruments and a small video camera. The camera sends a magnified image from inside the body to a video monitor, giving the surgeon a close-up view of the organs and tissues. The surgeon watches the monitor and performs the operation by manipulating the surgical instruments through separate small incisions. The gallbladder is identified and carefully separated from the liver and other structures. Finally, the cystic duct is cut and the gallbladder removed through one of the small incisions. This type of surgery requires meticulous surgical skill.
Laparoscopic cholecystectomy does not require the abdominal muscles to be cut, resulting in less pain, quicker healing, less scarring and fewer complications such as infection. The recovery period is usually only one night in the hospital and several days at home.
The most common complication of laparoscopic cholecystectomy is injury to the common bile duct, which connects the gallbladder and liver. An injured bile duct can leak bile and cause a painful and potentially dangerous infection. Many cases of minor injury to the common bile duct can be managed nonsurgically. Major injury to the bile duct, however, is a very serious problem and may require corrective surgery. At this time it is unclear whether these complications are more common after laparoscopic cholecystectomy vs. standard cholecystectomy.
In addition to surgery, nonsurgical approaches have been pursued but are used only in special situations and only for gallstones that are predominantly of the cholesterol type.
Oral dissolution therapy with ursodiol (Actigall) and chenodiol (Chenix) works best for small cholesterol gallstones. These medicines are made from the acid naturally found in bile. They most often are used in individuals who cannot tolerate surgery. Treatment may be required for months to years before gallstones are dissolved.
Mild diarrhea is a side effect of both drugs. Chenodiol may also temporarily elevate the liver enzyme transaminase and mildly elevate blood cholesterol levels.
Two therapies, contact dissolution with methyltert butyl ether instillation through a catheter placed into the gallbladder and extracorporeal shock-wave lithotripsy (ESWL), are still experimental.
Each of these alternatives to gallbladder surgery leaves the gallbladder intact; so stone recurrence, which happens in about one-half the cases, is still a likely possibility.