Gallstones are collections of solid material (predominantly crystals of cholesterol) in the gallbladder.
Most disorders of the gallbladder and bile ducts result from gallstones. Gallstones are more common among women and among certain groups of people, such as American Indians. The risk factors for gallstones include the following:
In the United States, about 20% of people older than age 65 have gallstones.
Stones in the gallbladder (called cholelithiasis) sometimes pass into the bile ducts. Stones in the bile ducts are called choledocholithiasis. These stones sometimes block a bile duct.
Most gallstones do not cause symptoms. But if symptoms or other problems occur, treatment is necessary. Each year, more than half a million people in the United States have their gallbladder surgically removed.
In the Western world, the major component of most gallstones is cholesterol, a fat (lipid) that normally is dissolved in bile (but not in water). When the liver secretes excess cholesterol, bile becomes oversaturated with cholesterol. The excess forms solid particles (cholesterol crystals). These microscopic crystals accumulate in the gallbladder, where they clump and grow into gallstones. Other types of gallstones begin with precipitates of calcium compounds and bilirubin (the main pigment in bile). Stones composed of bilirubin, called pigment stones, are either black (forming in the gallbladder) or brown (forming in the bile ducts).
The stones may stay in the gallbladder or pass into bile ducts. Stones can block the cystic duct, common bile duct, or ampulla of Vater (where the common bile duct and pancreatic duct join). Most cholesterol stones in the bile ducts came from the gallbladder. Any narrowing (stricture) of the bile ducts can lead to a blockage or slow bile flow. Bacterial infections can develop when bile flow is slowed or blocked. Bile duct strictures, in turn, can lead to infection, inflammation, and thus brown pigment stones in the bile ducts.
Sometimes microscopic particles of cholesterol, calcium compounds, bilirubin, and other materials accumulate but do not form stones. This material is called biliary sludge. Sludge develops when bile remains in the gallbladder too long, for example, as it does during pregnancy. Gallbladder sludge usually disappears when its cause resolves, for example, when pregnancy ends. Sludge, however, can evolve into gallstones or pass into the biliary tract and block the ducts.
About 80% of people with gallstones do not have any symptoms for many years, if ever, particularly if the gallstones remain in the gallbladder.
Gallstones may cause pain. Pain develops when the stones pass from the gallbladder into the cystic duct, common bile duct, or ampulla of Vater and block the duct. Then the gallbladder swells, causing pain called biliary colic. The pain is felt in the upper abdomen, usually on the right side under the ribs. Sometimes the location is hard to pinpoint, particularly for people with diabetes and older people. The pain typically increases in intensity over 15 minutes to an hour and remains steady for up to 12 hours. The pain is usually severe enough to send people to the emergency department for relief. Then the pain resolves over 30 to 90 minutes, leaving a dull ache. People often feel nauseated and vomit.
Eating a heavy meal can trigger biliary colic, but simply eating fatty foods does not. Gallstones do not cause belching or bloating. Nausea occurs only when biliary colic occurs.
Although most episodes of biliary colic resolve spontaneously, pain returns in 20 to 40% of people each year, and complications may develop. Between episodes, people feel well.
If the blockage persists, the gallbladder becomes inflamed (a condition called acute cholecystitis, see Gallbladder and Bile Duct Disorders: Cholecystitis). When the gallbladder is inflamed, bacteria flourish, and infection may develop. The inflammation usually causes fever.
Blockage of the common bile duct or the ampulla of Vater is more serious than blockage of the cystic duct. Blockage of a bile duct can cause the ducts to widen (dilate). It can also cause fever, chills, and jaundice (a yellowish discoloration of the skin and the whites of the eyes). This combination of symptoms indicates that a serious infection called acute cholangitis has developed. Bacteria can spread to the bloodstream and cause serious infections elsewhere in the body. Also, pockets of pus (abscesses) can develop in the liver.
Stones that block the ampulla of Vater also can block the pancreatic duct, causing inflammation of the pancreas (pancreatitis), as well as pain.
Inflammation of the gallbladder caused by gallstones can erode the gallbladder wall, sometimes resulting in a hole (perforation). Perforation results in leakage of the gallbladder contents throughout the abdominal cavity, causing severe inflammation (peritonitis). A large gallstone that enters the small intestine can cause intestinal blockage, called a gallstone ileus. Though rare, this complication is more likely to occur in older people.
Doctors suspect gallstones in people with the characteristic pain in the upper abdomen (caused by a swollen gallbladder). Sometimes gallstones are detected when an imaging test such as ultrasonography is done for other reasons.
Ultrasonography is essential. It is 95% accurate in detecting gallstones in the gallbladder. It is less accurate in detecting stones in the bile ducts, but it may show that the blockage has caused the ducts to dilate. Other diagnostic tests may be necessary. They include magnetic resonance imaging (MRI) of the bile and pancreatic ducts, computed tomography (CT), and endoscopic retrograde cholangiopancreatography (ERCP—see Diagnosis of Liver, Gallbladder, and Biliary Disorders:Tests for Liver, Gallbladder, and Biliary Disorders and Gallbladder and Bile Duct Disorders: Gallstones in the Bile Ducts).
Blood test results are usually normal unless stones block the bile ducts. Then, the liver tests are abnormal, suggesting a backup of bile in the liver (cholestasis). Results often include an increase in bilirubin and certain liver enzymes.
Gallstones that do not cause symptoms (silent gallstones) do not require treatment. If gallstones cause pain, changing the diet (for example, to a low-fat diet) does not help.
Gallstones in the Gallbladder:
If gallstones cause disruptive, recurring episodes of pain, a doctor may recommend surgical removal of the gallbladder (cholecystectomy). Removal of the gallbladder prevents episodes of biliary colic yet does not affect digestion. No special dietary restrictions are required after surgery. During cholecystectomy, the doctor may also check for stones in the bile ducts.
About 90% of cholecystectomies are done using a flexible viewing tube called a laparoscope. After small incisions are made in the abdomen, the laparoscope is inserted. Surgical tools are passed through the incisions and used to remove the gallbladder. Laparoscopic cholecystectomy has lessened the discomfort after surgery, shortened the length of hospital stays, provided better cosmetic results, and reduced the time needed to recover.
The rest of cholecystectomies are done by open abdominal surgery, which requires a larger incision in the abdomen.
Alternatively, gallstones can be dissolved with drugs, such as bile acids (ursodeoxycholic acid). Such a drug, taken daily, can dissolve tiny stones in 6 months. Larger stones may take up to 1 to 2 years. Many never dissolve. Dissolving gallstones with drugs works only when stones are made of cholesterol and the opening of the gallbladder is not blocked. Even if the stones are successfully dissolved, half of these people develop gallstones again within 5 years. This treatment has limited use, and doctors reserve it for the few in whom surgery is too risky (for example, for those with major medical problems).
Gallstones in the Bile Ducts:
Stones in the bile ducts are removed during ERCP. With ERCP, a flexible viewing tube (endoscope) with surgical attachments is passed through the mouth, down the esophagus, through the stomach, and into the small intestine (see Understanding Endoscopic Retrograde Cholangiopancreatography). A thin catheter is passed through the endoscope, into the sphincter of Oddi, and up into the common bile duct. A dye that is visible on x-rays (radiopaque dye) is then injected through the catheter into the bile ducts, and x-rays are taken to detect any abnormalities.
Most stones can be removed during ERCP. An instrument passed through the endoscope is used to cut the sphincter of Oddi, where the ampulla of Vater (lower bile duct) joins the small intestine—a procedure called endoscopic sphincterotomy. If the stones do not spill out into the small intestine on their own after the cut is made, a catheter with a small basket at its tip can be used to trap and then pull the stone out of the duct. Cutting the end of the bile duct leaves the opening wide enough to let any future stones pass more easily into the small intestine. Gallstones located in the gallbladder cannot be removed by this technique.
ERCP with endoscopic sphincterotomy is successful in 90% of people. It is far safer than open abdominal surgery. Fewer than 1% of people die from this procedure, and 1 to 2% experience complications. Immediate complications include bleeding, inflammation of the pancreas (pancreatitis), and perforation or infection of the bile ducts. Later on, some (2 to 6%) of the people who have this procedure develop narrowing of the inflamed ducts (strictures). Narrowing leads to stones forming in the ducts, causing further duct blockages.
Most people who have had ERCP and endoscopic sphincterotomy later have their gallbladder removed, typically using a laparoscope. If the gallbladder remains, they are at risk of later developing acute gallbladder problems or passing stones into the ducts, causing repeated blockages.
Last full review/revision December 2007 by Eldon A. Shaffer, MD