What Are Gallstones?
Gallstones form when
liquid stored in the
gallbladder hardens into pieces of
stone-like material. The liquid, called
bile, is used to help the body
digest fats.
Bile is made in the
liver, then stored in the
gallbladder until the body needs to
digest fat. At that time, the
gallbladder contracts and pushes the
bile into a tube—called a duct—that carries it to the small
intestine, where it helps with
digestion.
Bile contains
water,
cholesterol,
fats,
bile salts, and
bilirubin. Bile salts break up fat, and
bilirubin gives
bile and
stool a
brownish color. If the liquid
bile contains too much
cholesterol,
bile salts, or
bilirubin, it can harden into
stones.
The two types of
gallstones are
cholesterol stones and
pigment stones. Cholesterol stones are usually yellow-green and are made primarily of hardened
cholesterol. They account for about 80 percent of gallstones. Pigment stones are small, dark stones made of
bilirubin. 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.
Gallstones can block the normal flow of
bile if they
lodge in any of the
ducts that carry
bile from the
liver to the
small intestine. That includes the
hepatic duct, which carry
bile out of the
liver; the
cystic duct, which takes
bile to and from the
gallbladder; and the
common bile duct, which takes
bile from the cystic and hepatic duct to the
small intestine.
Bile trapped in these ducts can cause
inflammation in the
gallbladder, the
ducts, or, rarely, the
liver. Other ducts open into the
common bile duct, including the
pancreatic duct, which carries digestive
enzymes out of the
pancreas. If a
gallstone blocks the opening to that duct, digestive enzymes can become trapped in the
pancreas and cause an
extremely
painful inflammation called
pancreatitis.
If any of these ducts remain
blocked for a
significant period of time,
severe—possibly
fatal—
damage can occur, affecting the
gallbladder,
liver, or
pancreas.
Warning signs of a serious problem are
fever,
jaundice, and
persistent pain.
What Causes Gallstones?
Cholesterol Stones
Scientists believe
cholesterol stones form when
bile contains too much
cholesterol, too much
bilirubin, or not enough
bile salts, or when the
gallbladder does not empty as it should for some other reason.
Pigment Stones
The cause of
pigment stones is uncertain. They tend to develop in people who have
cirrhosis, biliary tract infections, and hereditary blood disorders such as
sickle cell anemia.
Other Factors
It is believed that the mere presence of
gallstones may cause more
gallstones to develop. However, other factors that contribute to gallstones have been identified, especially for
cholesterol stones.
- Obesity. Obesity is a major risk factor for gallstones, especially in women. A large clinical study showed that being even moderately overweight increases one's 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 decreases gallbladder emptying.
- Estrogen. 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.
- Ethnicity. 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. A 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.
- Gender. Women between 20 and 60 years of age are twice as likely to develop gallstones as men.
- Age. People over age 60 are more likely to develop gallstones than younger people.
- Cholesterol-lowering drugs. Drugs that lower cholesterol levels in blood actually increase the amount of cholesterol secreted in bile. This in turn can increase the risk of gallstones.
- Diabetes. People with diabetes generally have high 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 bile, which can cause gallstones.
- Fasting. Fasting decreases gallbladder movement, causing the bile to become overconcentrated with cholesterol, which can lead to gallstones.
Who Is at Risk for Gallstones?
What are the Symptoms?
Symptoms of
gallstones are often called a gallstone "
attack" because they occur suddenly. A typical attack can cause
Gallstone attacks often follow
fatty
meals, and they may occur during the
night. Other
gallstone symptoms include
People who also have the following symptoms should see a doctor right away:
Many people with
gallstones have no
symptoms. These patients are said to be
asymptomatic, and these stones are called "
silent stones." They do not interfere in
gallbladder,
liver, or
pancreas function and do not need treatment.
How Are Gallstones Diagnosed?
Many
gallstones, especially
silent stones, are discovered by
accident during
tests for other problems. But when
gallstones are suspected to be the cause of symptoms, the doctor is likely to do an
ultrasound exam.
Ultrasound uses sound waves to create images of
organs. Sound waves are sent toward the
gallbladder through a handheld device that a technician glides over the
abdomen. The sound waves bounce off the
gallbladder,
liver, and other
organs, and their
echoes make electrical impulses that create a picture of the organ on a video
monitor. If
stones are present, the sound waves will bounce off them, too, showing their location.
Other tests used in diagnosis include
Gallstone
symptoms are similar to those of
heart attack,
appendicitis,
ulcers,
irritable bowel syndrome,
hiatal hernia,
pancreatitis, and
hepatitis. So accurate
diagnosis is important.
What is the Treatment?
Surgery
Surgery to remove the
gallbladder is the most common way to treat
symptomatic gallstones. (Asymptomatic gallstones usually do not need treatment.) Each year more than 500,000 Americans have
gallbladder surgery. The surgery is called
cholecystectomy.
The standard surgery is called
laparoscopic cholecystectomy. For this
operation, the
surgeon makes several tiny
incisions in the
abdomen and inserts surgical instruments and a miniature video camera into the
abdomen. The
camera sends a magnified image from inside the body to a video monitor, giving the
surgeon a closeup view of the
organs and
tissues. While watching the monitor, the surgeon uses the instruments to carefully separate the
gallbladder from the
liver,
ducts, and other structures. Then the
cystic duct is cut and the
gallbladder removed through one of the small incisions.
Because the abdominal
muscles are not cut during
laparoscopic surgery, patients have less pain and fewer complications than they would have had after
surgery using a large
incision across the
abdomen. Recovery usually involves only one night in the
hospital, followed by several days of restricted
activity at
home.
If the
surgeon discovers any
obstacles to the laparoscopic procedure, such as
infection or
scarring from other
operations, the operating team may have to switch to open surgery. In some cases the obstacles are known before surgery, and an open surgery is planned. It is called "open" surgery because the
surgeon has to make a 5- to 8-inch
incision in the abdomen to remove the
gallbladder. This is a
major surgery and may require about a 2- to 7-day stay in the
hospital and several more weeks at home to
recover. Open surgery is required in about 5 percent of
gallbladder operations.
The most common
complication in
gallbladder surgery is injury to the
bile ducts. An injured
common bile duct can leak bile and cause a painful and potentially
dangerous infection.
Mild injuries can sometimes be treated nonsurgically. Major
injury, however, is more serious and requires additional
surgery.
If
gallstones are in the
bile ducts, the surgeon may use ERCP in removing them before or during the
gallbladder surgery. Once the
endoscope is in the
small intestine, the surgeon locates the affected bile duct. An instrument on the
endoscope is used to cut the duct, and the
stone is captured in a tiny
basket and removed with the
endoscope. This two-step procedure is called ERCP with endoscopic sphincterotomy.
Occasionally, a person who has had a
cholecystectomy is diagnosed with a
gallstone in the bile ducts weeks, months, or even years after the
surgery. The two-step ERCP procedure is usually successful in removing the stone.
Nonsurgical Treatment
Nonsurgical approaches are used only in special situations—such as when a patient's condition prevents using an
anesthetic—and only for
cholesterol stones. Stones recur after nonsurgical treatment about half the time.
- Oral dissolution therapy. Drugs made from bile acid are used to dissolve the stones. The drugs, ursodiol (Actigall) and chenodiol (Chenix), work best for small cholesterol stones. Months or years of treatment may be necessary before all the stones dissolve. Both drugs cause mild diarrhea, and chenodiol may temporarily raise levels of blood cholesterol and the liver enzyme transaminase.
- Contact dissolution therapy. This experimental procedure involves injecting a drug directly into the gallbladder to dissolve stones. The drug—methyl tert butyl—can dissolve some stones in 1 to 3 days, but it must be used very carefully because it is a flammable anesthetic that can be toxic. The procedure is being tested in patients with symptomatic, noncalcified cholesterol stones.
- Extracorporeal shockwave lithotripsy (ESWL). This treatment uses shock waves to break up stones into tiny pieces that can pass through the bile ducts without causing blockages. Attacks of biliary colic (intense pain) are common after treatment, and ESWL's success rate is not very high. Remaining stones can sometimes be dissolved with medication.
Don't People Need Their Gallbladders?
Fortunately, the
gallbladder is an organ that people can live without. Losing it won't even require a change in
diet. Once the
gallbladder is removed,
bile flows out of the
liver through the
hepatic ducts into the
common bile duct and goes directly into the
small intestine, instead of being stored in the
gallbladder. However, because the
bile isn't stored in the
gallbladder, it flows into the
small intestine more frequently, causing
diarrhea in some people. Also, some studies suggest that removing the
gallbladder may cause higher blood
cholesterol levels, so occasional cholesterol tests may be necessary.
Points To Remember
National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
The National Digestive Diseases Information Clearinghouse (NDDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). NIDDK is part of the National Institutes of Health under the U.S. Department of Health and Human Services. Established in 1980, the clearinghouse provides information about digestive diseases to people with digestive disorders and to their families, health care professionals, and the public. NDDIC answers inquiries; develops, reviews, and distributes publications; and works closely with professional and patient organizations and Government agencies to coordinate resources about digestive diseases.
Publications produced by the clearinghouse are reviewed carefully for scientific accuracy, content, and readability.
This e-text is not copyrighted. The clearinghouse encourages users of this e-pub to duplicate and distribute as many copies as desired.
NIH Publication No. 99-2897
November 1998
e-text posted: January 1999