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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.
The gallbladder and the ducts that carry bile and other
digestive enzymes from the liver, gallbladder, and pancreas
to the small intestine are called the biliary system.
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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 ducts, 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
ducts 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.
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.
- Women.
- People over age
60.
- Native Americans.
- Mexican-Americans.
- Overweight men
and women.
- People who fast
or lose a lot of weight quickly.
- Pregnant women,
women on hormone therapy, and women who use birth control
pills.
Symptoms of gallstones
are often called a gallstone "attack" because they occur suddenly.
A typical attack can cause
- Steady, severe
pain in the upper abdomen that increases rapidly and lasts
from 30 minutes to several hours.
- Pain in the back
between the shoulder blades.
- Pain under the
right shoulder.
- Nausea or vomiting.
Gallstone attacks
often follow fatty meals, and they may occur during the night.
Other gallstone symptoms include
- Abdominal bloating.
- Recurring intolerance
of fatty foods.
- Colic.
- Belching.
- Gas.
- Indigestion.
People who also have
the following symptoms should see a doctor right away:
- Sweating.
- Chills.
- Low-grade fever.
- Yellowish color
of the skin or whites of the eyes.
- Clay-colored stools.
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.
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
- Cholecystogram
or cholescintigraphy. The patient is injected with a special
iodine dye, and x-rays are taken of the gallbladder over a
period of time. (Some people swallow iodine pills the night
before the x-ray.) The test shows the movement of the gallbladder
and any obstruction of the cystic duct.
- Endoscopic
retrograde cholangiopancreatography (ERCP). The patient
swallows an endoscope—a long, flexible, lighted tube connected
to a computer and TV monitor. The doctor guides the endoscope
through the stomach and into the small intestine. The doctor
then injects a special dye that temporarily stains the ducts
in the biliary system. ERCP is used to locate stones in the
ducts.
- Blood tests.
Blood tests may be used to look for signs of infection, obstruction,
pancreatitis, or jaundice.
Gallstone symptoms
are similar to those of heart attack, appendicitis, ulcers,
irritable bowel syndrome, hiatal hernia, pancreatitis, and hepatitis.
So accurate diagnosis is important.
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.
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.
- Gallstones form
when substances in the bile harden.
- Gallstones are
common among women, Native Americans, Mexican-Americans, and
people who are overweight.
- Gallstone attacks
often occur after eating a fatty meal.
- Symptoms can mimic
those of other problems, including heart attack, so accurate
diagnosis is important.
- Gallstones can
cause serious problems if they become trapped in the bile
ducts.
- Laparoscopic surgery
to remove the gallbladder is the most common treatment.
National Digestive
Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892-3570
E-mail: nddic@info.niddk.nih.gov
NIH Publication
No. 99-2897
November 1998
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